Patent Publication Number: US-2022219002-A1

Title: Collection of clinical data for graphical representation and analysis

Description:
RELATED APPLICATION DATA 
     The present application claims the benefit under 35 U.S.C. § 119 to U.S. provisional patent application Ser. No. 61/491,092, filed May 27, 2011. The foregoing application is hereby incorporated by reference into the present application in its entirety. 
    
    
     FIELD OF THE INVENTION 
     The present invention relates to tissue stimulation systems, and more particularly, to user Interfaces and methods for controlling the distribution of electrical current on neurostimulation leads. 
     BACKGROUND OF THE INVENTION 
     Implantable neurostimulation systems have proven therapeutic in a wide variety of diseases and disorders. Pacemakers and Implantable Cardiac Defibrillators (ICDs) have proven highly effective in the treatment of a number of cardiac conditions (e.g., arrhythmias). Spinal Cord Stimulation (SCS) systems have long been accepted as a therapeutic modality for the treatment of chronic pain syndromes, and the application of tissue stimulation has begun to expand to additional applications, such as angina pectoris and incontinence. Further, in recent investigations, Peripheral Nerve Stimulation (PNS) systems have demonstrated efficacy in the treatment of chronic pain syndromes and incontinence, and a number of additional applications are currently under investigation. 
     More pertinent to the present inventions described herein. Deep Brain Stimulation (DBS) has been applied therapeutically for well over a decade for the treatment of neurological disorders, including Parkinson&#39;s Disease, essential tremor, dystonia, and epilepsy, to name but a few. Further details discussing the treatment of diseases using DBS are disclosed in U.S. Pat. Nos. 6,845,267, 6,845,267, and 6,950,707, which are expressly incorporated herein by reference. 
     Each of these implantable neurostimulation systems typically includes one or more electrode carrying stimulation leads, which are implanted at the desired stimulation site, and a neurostimulator implanted remotely from the stimulation site, but coupled either directly to the neurostimulation lead(s) or indirectly to the neurostimulation lead(s) via a lead extension. The neurostimulation system may further comprise a handheld external control device to remotely instruct the neurostimulator to generate electrical stimulation pulses in accordance with selected stimulation parameters. Typically, the stimulation parameters programmed into the neurostimulator can be adjusted by manipulating controls on the external control device to modify the electrical stimulation provided by the neurostimulator system to the patient. 
     Thus, in accordance with the stimulation parameters programmed by the external control device, electrical pulses can be delivered from the neurostimulator to the stimulation electrode(s) to stimulate or activate a volume of tissue in accordance with a set of stimulation parameters and provide the desired efficacious therapy to the patient. The best stimulus parameter set will typically be one that delivers stimulation energy to the volume of tissue that must be stimulated (the target tissue region) in order to provide the therapeutic benefit (e.g., treatment of movement disorders), while minimizing the non-target tissue region that is stimulated. A typical stimulation parameter set may include the electrodes that are acting as anodes or cathodes, as well as the amplitude, duration, and rate of the stimulation pulses. 
     Significantly, non-optimal electrode placement and stimulation parameter selections may result in excessive energy consumption due to stimulation that is set at too high an amplitude, too wide a pulse duration, or too fast a frequency; inadequate or marginalized treatment due to stimulation that is set at too low an amplitude, too narrow a pulse duration, or too slow a frequency; or stimulation of neighboring cell populations that may result in undesirable side-effects. 
     For example, bilateral DBS of the subthalamic nucleus has been proven to provide effective therapy for improving the major motor signs of advanced Parkinson&#39;s disease, and although the bilateral stimulation of the subthalamic nucleus is considered safe, an emerging concern is the potential negative consequences that it may have on cognitive functioning and overall quality of life (see A. M. M. Frankemolle. et at.,  Reversing Cognitive - Motor Impairments in Parkinson&#39;s Disease Patients Using a Computational Modelling Approach to Deep Brain Stimulation Programming , Brain 2010; pp. 1-16). In large part, this phenomenon is due to the small size of the subthalamic nucleus, which may range from the size of a pea to the size of a peanut, with varying shapes from spherical to kidney-shape. Even with the electrodes are located predominately within the sensorimotor territory, the electric field generated by DBS is non-discriminately applied to all neural elements surrounding the electrodes, thereby resulting in the spread of current to neural elements affecting cognition. As a result, diminished cognitive function during stimulation of the subthalamic nucleus may occur do to non-selective activation of non-motor pathways within or around the subthalamic nucleus. 
     Thus, it is crucial that proper location and maintenance of the lead position be accomplished in order to continuously achieve efficacious therapy. Lead displacements of less than a millimeter may have a deleterious effect on the patient&#39;s therapy. Because the stimulation region needs to be in the correct location to achieve optimal therapy and minimization of side-effects, stimulation leads typically carry many electrodes (e.g., four), so that at least one of the electrodes is near the target and allow programming of the electrodes to place the stimulation field in that region of interest. 
     The large number of electrodes available, combined with the ability to generate a variety of complex stimulation pulses, presents a huge selection of stimulation parameter sets to the clinician or patient. In the context of DBS, neurostimulation leads with a complex arrangement of electrodes that not only are distributed axially along the leads, but are also distributed circumferentially around the neurostimulation leads as segmented electrodes, can be used. 
     To facilitate such selection, the clinician generally programs the external control device, and if applicable the neurostimulator, through a computerized programming system. This programming system can be a self-contained hardware/software system, or can be defined predominantly by software running on a standard personal computer (PC). The PC or custom hardware may actively control the characteristics of the electrical stimulation generated by the neurostimulator to allow the optimum stimulation parameters to be determined based on patient feedback and to subsequently program the external control device with the optimum stimulation parameters. 
     When electrical leads are implanted within the patient, the computerized programming system may be used to instruct the neurostimulator to apply electrical stimulation to test placement of the leads and/or electrodes, thereby assuring that the leads and/or electrodes are implanted in effective locations within the patient. Once the leads are correctly positioned, a fitting procedure, which may be referred to as a navigation session, may be performed using the computerized programming system to program the external control device, and if applicable the neurostimulator, with a set of stimulation parameters that best addresses the neurological disorder(s). 
     As physicians and clinicians become more comfortable with implanting neurostimulation systems and time in the operating room decreases, post-implant programming sessions are becoming a larger portion of process. Furthermore, because the body tends to adapt to the specific stimulation parameters currently programmed into a neurostimulation system, or the full effects of stimulation are not manifest in a short period of time (i.e., not observed within a programming session), follow-up programming procedures are often needed. 
     For example, in the context of DBS, the brain is dynamic (e.g., due to disease progression, motor re-learning or other changes), and a program (i.e., a set of stimulation parameters) that is useful for a period of time may not maintain its effectiveness and/or the expectations of the patient may increase. Further, physicians typically treat the patient with stimulation and medication, and proper amounts of each are required for optimal therapy. Thus, after the DBS system has been implanted and fitted, the patient may have to schedule another visit to the physician in order to adjust the stimulation parameters of the DBS system if the treatment provided by the implanted DBS system is no longer effective or otherwise is not therapeutically or operationally optimum due to, e.g., disease progression, motor re-learning, or other changes. 
     Regardless of the skill of the physician or clinician, neurostimulation programming sessions can be especially lengthy when programming complicated neurostimulation systems, such as DBS systems, where patients usually cannot feel the effects of stimulation, and the effects of the stimulation may be difficult to observe, are typically subjective, or otherwise may take a long time to become apparent. Clinical estimates suggest that 13-36 hours per patient are necessary to program and assess DBS patients with current techniques (see Hunka K. et al.,  Nursing Time to Program and Assess Deep Brain Stimulators in Movement Disorder Patients , J. Neursci Nurs. 37: 204-10), which is an extremely large time commitment for both the physician/clinician and the patient. 
     Significantly contributing to the lengthy process of programming neurostimulation system is the fact the location of the electrodes relative to the target tissue region is not exactly known when the neurostimulation lead or leads are initially implanted within the brain of the patient. In a typical programming session, the boundaries of a targeted region or structure relative to the electrodes can be determined by observing and recording a substantial amount of clinical information observed during the programming session of each patient is recorded. Typically this is accomplished by incrementally increasing the amplitude of electrical stimulation energy on each individual electrode one at a time, for each amplitude increment, observing and manually recording on a relatively large paper spread sheet, clinical information, such as the types of therapeutic effects and side-effects, the threshold values of these therapeutic effects and side-effects. the extent of these therapeutic effects and side-effects. Based on this observed information, the physician or clinician may determine the electrodes having the greatest influence on the surrounding tissue, whether such influence causes a therapeutic effect or a side-effect, the neurostimulation system can be programmed with the best stimulation parameter sets (i.e., those that maximize the volume of target tissue, while minimizing the volume of non-target tissue). 
     Notably, as the stimulation level of the electrodes that within the targeted region is incrementally increased., first a therapeutic level is reached, and then unwanted side-effects are reached. The boundaries of the target tissue region are determined to be around the therapeutic level, but below the side-effects level. The electrodes located outside of the target tissue region (in theory) have not therapeutic level, only a side-effect level. Once the boundaries the target tissue region are determined, the neurostimulation system can be programmed, such that the resulting electrical stimulation field covers the target tissue region (i.e., the shape and size of the electrical stimulation matches the shape and size of the target tissue region). 
     While the manual recording of this clinical information has some utility in facilitating programming sessions, the recorded clinical information is not represented to the physician or clinician in a manner that the physician or clinician can readily taken advantage of in the current programming session, and certainly during subsequent programming sessions where the same physician or clinician will not have access to this recorded clinical information. 
     To facilitate determination of the location of the electrodes relative to the target tissue region or regions, and even the non-target tissue region or regions, a computerized programming system may optionally be capable of storing one or more anatomical regions of interest, which may be registered within the neurostimulation leads when implanted with the patient. 
     The anatomical region of interest may be a target tissue region, the stimulation of which is known or believed to provide the needed therapy to the patient. For example, if the DBS indication is Parkinson&#39;s disease, the target tissue region may be the subthalamic nucleus (STN) or the globus pallidus (GPi). If the DBS indication is Essential Tremor, the target tissue region may be the thalamus. If the DBS indication is depression, the target tissue region may be one or more of the nucleus acumbens, ventral striatum, ventral capsule, anterior capsule, or the Brodmann&#39;s area 25. If the DBS indication is epilepsy, the target tissue region may be preferably the anterior nucleus. If the DBS indication is a gait disorder, the target tissue region may be the pedunculopontine nucleus (PPN). If the DBS indication is dementia, Alzheimer&#39;s disease or memory disorders, the target tissue region may be anywhere in the Papez circuit. 
     The anatomical region of interest may be a non-target tissue region, the stimulation of which is known or believed to provide an undesirable side-effect for the patient. For example, stimulation of medial to the STN may cause eye deviations, and stimulation of the substantia nigra may cause symptoms of depression. 
     Notably, the anatomical region of interest may not be strictly anatomical, but rather may simply represent some arbitrary volume of tissue that, when stimulated, provides therapy or creates a side-effect. The anatomical region of interest may be naturally defined (e.g., an anatomical structure corresponding to the target tissue volume may naturally provide the boundaries that delineate it from the surrounding tissue) or may be defined by a graphical marking). The anatomical region of interest may be obtained from a generally available atlas, and in the case of DBS. a brain atlas, which may be derived from the general population or a previous patient, or may be obtained from a patient specific atlas derived from, e.g., a magnetic resonant imager (MRI), computed tomography (CT), X-ray, fluoroscopy, ventriculography, ultrasound, or any other imaging modality or a merging of any or all of these modalities. 
     Although the use of a generalized atlas may be quite helpful when optimizing the stimulation parameters that are ultimately programmed into the neurostimulation system, these types of atlases are not patient specific, and thus, cannot account for patient specific physiology. Even if a patient-specific atlas is used, any errors in registration with the neurostimulation leads may prevent optimized programming of the neurostimulation system. 
     There, thus, remains a need for a user interface that more efficiently allows the programming of neurostimulation systems. 
     SUMMARY OF THE INVENTION 
     In accordance with a first aspect of the present inventions, a method of treating a patient is provided. The method comprises serially conveying electrical stimulation energy into tissue (e.g., brain tissue) of the patient via different combinations of electrodes implanted within the patient, thereby creating one or more clinical effects (e.g., a therapeutic effect and/or a side-effect) for each of the different electrode combinations. In one embodiment, each electrode combination has only one electrode. In another embodiment, at least one of the electrode combinations comprises a fractionalized electrode combination. 
     The method further comprises determining an influence of each of the different electrode combinations on the clinical effect(s), and generating a graphical indication of the clinical effect(s) based on the determined electrode combination influences. The method further comprises displaying a graphical representation of the electrodes, and displaying the graphical indication of the clinical effect(s) adjacent the graphical electrode representation, such that a user can determine an extent to which each of the different electrode combinations influences the clinical effect(s). The electrical stimulation energy may be conveyed from a neurostimulator, in which case, the method may further comprise programming the neurostimulator based on the determined extent to which the each different electrode combination influences the clinical effects(s). The method may further comprise recording data in computer memory indicating the determined influence of the each different electrode combination on the clinical effect(s). 
     One method further comprises incrementally increasing an intensity level of the conveyed electrical stimulation energy for each of the different electrode combinations, wherein the influence of the each different electrode combination on the clinical effect(s) is determined for each of the incremental intensity levels. In this case, the clinical effect(s) may include one or more therapeutic effects, and the influence of the each different electrode combination on the therapeutic effect(s) may be determined by determining the range of incremental intensity levels at which a metric of the therapeutic effect(s) (e.g., a perception threshold of the therapeutic effect(s)) occurs. 
     In this method, the clinical effect(s) may further comprise one or more side-effects. and the influence of the each different electrode combination on the side-effect(s) may be determined by determining the incremental intensity level at which a metric of the side-effect(s) (e.g., a perception threshold of the side-effect(s), an uncomfortable threshold of the side-effect(s) or an intolerable threshold of the side-effect(s) initially occurs. In this case, the influence of the each different electrode combination on the therapeutic effect(s) may further be determined by determining the highest intensity level at which the therapeutic effect, metric(s) occur prior to the initial occurrence of the side-effect metric(s). The graphical indication of the clinical effect(s) may comprise a bar map having a plurality of bars, each of which indicates for the each different electrode combination the highest intensity level at which the therapeutic effect metric(s) occur prior to the initial occurrence of the side-effect metric(s). 
     In this method, the therapeutic effect metric may alternatively be a relative level of the therapeutic effect(s), in which case, the graphical indication of the clinical effect(s) may comprise a bar map for each of the electrode combinations, each bar map having a bar indicating the relative level of the therapeutic effect(s) at the each incremental intensity level. The therapeutic effect(s) may comprise a plurality of therapeutic effects, and the relative level may be a composite score as a function of individual scores of the therapeutic effects. 
     In this method, the influence of the each different electrode combination on the clinical effect(s) may alternatively be determined by determining the electrode combinations that most influence the therapeutic effect(s), and wherein the graphical indication of the clinical effect(s) comprises at least one target tissue region displayed adjacent the electrode combinations in the graphical electrode representation determined to most influence the therapeutic effect(s). In this case, the influence of the each different electrode combination on the clinical effect(s) may be determined by determining the electrode combinations that most influence the side-effect, and the graphical indication of the clinical effect(s) may comprise at least one non-target tissue region displayed adjacent the electrode combinations in the graphical electrode representation determined to most influence the side-effect. Optionally, this method may further comprise estimating one of an electric field or a region of tissue activation at the highest incremental intensity level at which the therapeutic effect(s) occurs for the each different electrode combination, in which case, the target tissue region may be based on the estimated electric field or region of tissue activation. 
     In accordance with a second aspect of the present inventions, an external programmer for use with a neurostimulator is provided. The neurostimulator comprises output circuitry configured for communicating with the neurostimulator, and control circuitry configured for instructing the neurostimulator via the output circuitry to serially convey electrical stimulation energy into tissue of a patient via different combinations of electrodes implanted within the patient, thereby creating one or more clinical effects (e.g.. a therapeutic effect and/or a side-effect) for each of the different electrode combinations. In one embodiment, each electrode combination has only one electrode. In another embodiment, at least one of the electrode combinations comprises a fractionalized electrode combination. 
     The neurostimulator further comprises processing circuitry configured for determining an influence of each of the different electrode combinations on the clinical effect(s), and generating a graphical indication of the clinical effect(s) based on the determined electrode combination influences. The control circuitry is further configured for instructing a display device to display the graphical indication of the clinical effect(s) adjacent a graphical representation of the electrodes, such that the user can determine an extent to which each of the different electrode combinations influences the clinical effect(s). The control circuitry may further be configured for programming the neurostimulator via the output circuitry based on the determined extent to which the each different electrode combination influences the clinical effect(s). 
     The external programmer may further comprise a user interface configured for allowing a user to enter clinical information on the clinical effect(s) for each different electrode combination, in which case, the processing circuitry may be configured for determining the influence of the each different electrode combination on the clinical effect(s) based on the clinical information entered by the user. The processing circuitry may determine the influence of each of the different electrode combinations on the clinical effect(s) by, e g., deriving such influence from the clinical information entered by the user, or if the clinical information entered by the user is, itself, an influence of each of the different electrode combinations on the clinical effect(s). by merely accepting the clinical information as such influence. The external programmer may further comprise monitoring circuitry configured for monitoring the clinical effect(s) for each different electrode combination, in which case, the processing circuitry may be configured for determining the influence of the each different electrode combination on the clinical effects) based on the monitored clinical effect(s). The external programmer may further comprise memory configured for storing data indicating the determined influence of the each different electrode combination on the clinical effect(s). 
     In one embodiment, control circuitry is further configured for instructing the neurostimulator via the output circuitry to incrementally increase an intensity level of the conveyed electrical stimulation energy for each of the different electrode combinations, and the processing circuitry is configured for determining the influence of the each different electrode combination on the clinical effect(s) for each of the incremental intensity levels. In this case, the clinical effect(s) may comprise one or more therapeutic effects, and the processing circuitry may be configured for determining the influence of the each different electrode combination on the therapeutic effect(s) by determining the range of incremental intensity levels at which a metric of the therapeutic effect(s) (e.g., a perception threshold of the therapeutic effect(s)) occurs. 
     In this embodiment, the clinical effect(s) may further comprises one or more side-effects, in which case, the processing circuitry may be further configured for determining the influence of the each different electrode combination on the side-effect(s) by determining the incremental intensity level at which a metric of the side-effect(s) (e.g., a perception threshold of the one or more side-effects, an uncomfortable threshold of the one or more side-effects. or an intolerable threshold of the one or more side-effects) initially occurs. The processing circuitry may be further configured for determining the influence of the each different electrode combination on the therapeutic effect(s) by determining the highest intensity level at which the therapeutic effect metric(s) occur prior to the initial occurrence of the side-effect metrics). The graphical indication of the clinical effect(s) may comprise a bar map having a plurality of bars, each of which indicates for the each different electrode combination the highest intensity level at which the therapeutic effect metric(s) occur prior to the initial occurrence of the side-effect metric(s). 
     In this embodiment, the therapeutic effect metric may alternatively be a relative level of the one or more therapeutic effects, in which case, the graphical indication of the clinical effects) may comprises a bar map for each of the electrode combinations, each bar map having a bar indicating the relative level of the therapeutic effect(s) at each incremental intensity level. The therapeutic effect(s) may comprises a plurality of therapeutic effects, and the relative level ma be composite score as a function of individual scores of the therapeutic effects. 
     In this embodiment, the processing circuitry may alternatively be configured for determining the influence of the each different electrode combination on the clinical effect(s) by determining the electrode combinations that most influence the therapeutic effect(s), and the graphical indication of the clinical effect(s) may comprise at least one target tissue region displayed adjacent the electrode combinations in the graphical electrode representation determined to most influence the therapeutic effect(s). The processing circuitry may further be configured for determining the influence of the each different electrode combination on the clinical effect(s) by determining the electrode combinations that most influence the side-effect, in which case, the graphical indication of the clinical effect(s) may comprise at least one non-target tissue region displayed adjacent the electrode combinations in the graphical electrode representation determined to most influence the side-effect. The processing circuitry may further be configured for estimating one of an electric field or a region of tissue activation at the highest incremental intensity level at which the therapeutic effects) occurs for the each different electrode combination, wherein the target tissue region is based on the estimated electric field or region of tissue activation. 
     In accordance with a third aspect of the present inventions, a method of treating a patient is provided. The method comprises conveying electrical stimulation energy into tissue (e.g., brain tissue) of the patient via a specified combination of a plurality of electrodes, thereby creating one or more clinical effects, and determining an influence of the specified electrode combination on the clinical effect(s). The method further comprises displaying an anatomical region of interest in registration with a graphical representation of the plurality of electrodes. The anatomical region of interest may be, e.g., an anatomical structure functionally delineated from surrounding tissue or an arbitrarily defined anatomical region of interest. The anatomical region of interest may be a therapy tissue region or a side-effect tissue region. 
     The method further comprises modifying the displayed anatomical region of interest based on the determined influence of the specified electrode combination on the clinical effect(s). The displayed anatomical region of interest may be modified by, e.g., spatially translating the displayed anatomical region of interest relative to the graphical electrode representation or changing the shape of the displayed anatomical region of interest. The electrical stimulation energy may be conveyed from a neurostimulator, in which case, the method may further comprise programming the neurostimulator based on the modified anatomical region of interest. The method may further comprise recording the modified anatomical region of interest in computer memory. 
     One method further comprises determining a displayed proximity between the displayed anatomical region of interest and the specified electrode combination in the graphical electrode representation, and implying an actual proximity between the anatomical region of interest and the specified electrode combination based on the determined influence of the specified electrode combination on the clinical effect(s). In this case, the displayed anatomical region of interest may be modified by spatially translating the displayed anatomical region of interest relative to the specified electrode combination in the graphical electrode representation to better match the displayed proximity to the actual proximity. If the displayed proximity is greater than the actual proximity, the displayed anatomical region of interest may be spatially translated closer to the specified electrode combination in the graphical electrode representation. If the displayed proximity is less than the actual proximity, the displayed anatomical region of interest may be spatially translated further from the specified electrode combination in the graphical electrode representation. 
     Another method further comprises displaying another anatomical region of interest in registration with a graphical representation of the plurality of electrodes, in which case, the clinical effect(s) comprise a therapeutic effect and a side-effect, the anatomical region of interest is a therapy tissue region, and the other anatomical region of interest is a side-effect tissue region. The influence of the specified electrode combination on the clinical effect(s) can be determined by determining a relative influence of the specified electrode combination on the therapeutic effect and the side-effect, and the displayed therapy tissue region and displayed side-effect tissue region may be modified by spatially translating the displayed therapy tissue region and the side-effect tissue region relative to the specified electrode combination in the graphical electrode representation based on the determined relative influence of the specified electrode combination on the therapeutic effect and the side-effect. 
     For example, if the specified electrode combination in the graphical electrode representation is closer to the displayed therapy tissue region than the displayed side-effect tissue region, the displayed therapy tissue region may be spatially translated further from the specified electrode combination in the graphical electrode representation and the displayed side-effect tissue region may be spatially translated closer to the specified electrode combination in the graphical electrode representation if the specified electrode combination is determined to influence the side-effect more than the therapeutic effect. 
     As another example, if the specified electrode combination in the graphical electrode representation is closer to the displayed side-effect tissue region than the displayed therapy tissue region, the displayed therapy tissue region may be spatially translated closer to the specified electrode combination in the graphical electrode representation and the displayed side-effect tissue region is spatially translated further from the specified electrode combination in the graphical electrode representation if the specified electrode combination is determined to influence the therapeutic effect more than the side-effect. 
     Still another method further comprises serially conveying electrical stimulation energy into the tissue of the patient via first and second combinations of the electrodes, thereby creating the clinical effect(s), with the first electrode combination in the graphical electrode representation being further away from the displayed anatomical region of interest than the second electrode combination in the graphical electrode representation. The method further comprises determining an influence of each of the first and second electrode combinations on the clinical effect(s). wherein the first electrode combination is determined to have a higher influence on the clinical effect(s) than the second electrode combination. The displayed anatomical region of interest may then be modified by spatially translating the displayed anatomical region of interest away from the second electrode combination in the graphical electrode representation towards the first electrode combination in the graphical electrode representation. 
     Yet another method further comprises serially conveying electrical stimulation energy into tissue of the patient via different combinations of electrodes implanted within the patient, thereby creating one or more clinical effects for each of the different electrode combinations. The clinical effect(s) comprises one or more therapeutic effects and one or more side-effects, and the displayed anatomical region is a therapy tissue region. The method further comprises incrementally increasing an intensity level of the conveyed electrical stimulation energy for each of the different electrode combinations, determining the influence of each different electrode combination on the clinical effect(s) by determining the highest intensity level at which a metric of the therapeutic effect(s) occurs prior to an initial occurrence of a metric of the side-effect(s). The displayed therapy tissue region may be modified by changing the shape of the therapy tissue region based on the determined highest intensity levels for the specified electrode combinations. 
     In accordance with a fourth aspect of the present inventions, an external programmer for use with a neurostimulator is provided. The external programmer comprises output circuitry configured for communicating with the neurostimulator, and control circuitry configured for instructing the neurostimulator via the output circuitry to convey electrical stimulation energy into the tissue of the patient via a specified combination of a plurality of electrodes, thereby creating one or more clinical effects, and for instructing a display device to display an anatomical region of interest in registration with a graphical representation of a plurality of electrodes. The anatomical region of interest may be, e.g., an anatomical structure functionally delineated from surrounding tissue or an arbitrarily defined anatomical region of interest. The anatomical region of interest may be a therapy tissue region or a side-effect tissue region. 
     The external programmer further comprises processing circuitry configured for determining an influence of the specified electrode combination on the clinical effect(s). The processing circuitry may determine the influence of each of the different electrode combinations on the clinical effect(s) by. e.g.. deriving such influence from clinical information entered by the user, or if the clinical information entered by the user is, itself, an influence of each of the different electrode combinations on the clinical effect(s), by merely accepting the clinical information as such influence. The processing circuitry is further configured for modifying the anatomical region of interest based on the determined influence of the specified electrode combination on the clinical effect(s). The displayed anatomical region of interest may be modified by, e.g., spatially translating the displayed anatomical region of interest relative to the graphical electrode representation or changing the shape of the displayed anatomical region of interest. The control circuitry may be further configured for programming the neurostimulator via the output circuitry based on the modified anatomical region of interest. The external programmer may further comprise memory configured for storing the modified anatomical region of interest. 
     In one embodiment, the processing circuitry is further configured for determining a displayed proximity between the displayed anatomical region of interest and the specified electrode combination in the graphical electrode representation, implying an actual proximity between the anatomical region of interest and the specified electrode combination based on the determined influence of the specified electrode combination on the clinical effect(s), and modifying the displayed anatomical region of interest by spatially translating the displayed anatomical region of interest relative to the specified electrode combination in the graphical electrode representation to better match the displayed proximity to the actual proximity. The processing circuitry may be configured for spatially translating the displayed anatomical region of interest closer to the specified electrode combination in the graphical electrode representation if the displayed proximity is greater than the actual proximity. The processing circuitry may be configured for spatially translating the displayed anatomical region of interest further from the specified electrode combination in the graphical electrode representation if the displayed proximity is less than the actual proximity. 
     In another embodiment, the control circuitry is further configured for instructing the display device to display another anatomical region of interest in registration with a graphical representation of a plurality of electrodes. In this case, the clinical effect(s) may comprise a therapeutic effect and a side-effect, the anatomical region of interest may be a therapy tissue region, the other anatomical region of interest may be a side-effect tissue region. The processing circuitry is configured for determining the influence electrode combination on the clinical effect(s) by determining a relative influence of the specified electrode combination on the therapeutic effect and the side-effect, and modifying the displayed therapy tissue region and displayed side-effect tissue region by spatially translating the displayed therapy tissue region and the side-effect tissue region relative to the specified electrode combination in the graphical electrode representation based on the determined relative influence of the specified electrode combination on the therapeutic effect and the side-effect. 
     In one example, if the specified electrode combination in the graphical electrode representation is closer to the displayed therapy tissue region than the displayed side-effect tissue region, the processing circuitry may be configured for spatially translating the displayed therapy tissue region further from the specified electrode combination in the graphical electrode representation and the displayed side-effect tissue region closer to the specified electrode combination in the graphical electrode representation if the specified electrode combination is determined to influence the side-effect more than the therapeutic effect. 
     In another example, if the specified electrode combination in the graphical electrode representation is closer to the displayed side-effect tissue region than the displayed therapy tissue region, the processing circuitry may be configured for spatially translating the displayed therapy tissue region closer to the specified electrode combination in the graphical electrode representation and the displayed side-effect tissue region further from the specified electrode combination in the graphical electrode representation if the specified electrode combination is determined to influence the therapeutic effect more than the side-effect. 
     In still another embodiment, the control circuitry is configured for serially conveying electrical stimulation energy into the tissue of the patient via first and second combinations of the electrodes, thereby creating the clinical effect(s), with the first electrode combination in the graphical electrode representation being further away from the displayed anatomical region of interest than the second electrode combination in the graphical electrode representation. The processing circuitry is configured for determining an influence of each of the first and second electrode combinations on the clinical effect(s). If the first electrode combinations is determined to have a higher influence on the clinical effect(s) than the second electrode combination, the processing circuitry may be further configured for modifying the displayed anatomical region of interest by spatially translating the displayed anatomical region of interest away from the second electrode combination in the graphical electrode representation towards the first electrode combination in the graphical electrode representation. 
     In yet another embodiment, the control circuitry is configured for serially conveying electrical stimulation energy into tissue of the patient via different combinations of electrodes implanted within the patient, thereby creating one or more clinical effects for each of the different electrode combinations. In this case, the clinical effect(s) comprises one or more therapeutic effects and one or more side-effects, and the displayed anatomical region is a therapy tissue region. The control circuitry is further configured for incrementally increasing an intensity level of the conveyed electrical stimulation energy for each of the different electrode combinations. The processing circuitry is configured for determining the influence of the each different electrode combination on the one or more clinical effects by determining the highest intensity level at which a metric of the therapeutic effect(s) occurs prior to an initial occurrence of a metric of the side-effect(s), and modifying the displayed therapy tissue region by changing the shape of the therapy tissue region based on the determined highest intensity levels for respective the specified electrode combinations. 
     In accordance with a fifth aspect of the present inventions, a method of treating a patient using a plurality of electrodes implanted within tissue (e.g., brain tissue) of the patient is provided. The method comprises selecting one of a plurality of different pre-defined shapes (e.g., a circular shape and a pear-shape) for an electric field, and defining a location of the electric field relative to a graphical representation of the electrodes. The method further comprises determining a combination of the electrodes (which may be fractionalized) based on the one selected shape and defined location of the electric field, and conveying electrical stimulation energy into the tissue of the patient via the determined electrode combination. In one method, the electrical stimulation energy is conveyed from a neurostimulator, in which case, the method may further comprise programming the neurostimulator to convey the electrical stimulation energy via the automatically determined electrode combination. 
     An optional method further comprises selecting another one of the plurality of different pre-defined shapes for another electric field, and defining a location of the other electric field relative to the graphical representation of the electrodes. In this case, the combination of the electrodes are determined based on both the one selected shape and defined location of the electric field and the other selected shape and defined location of the other electric field. Another optional method further comprises adjusting an intensity level of the conveyed electrical stimulation energy, wherein a size of the displayed electric field is adjusted in accordance with the adjusted intensity level. 
     A representation of the electric field may be displayed relative to the graphical electrode representation. In this case, the method may further comprise displaying a therapy tissue region, and comparing the displayed therapy tissue region to the plurality of different predefined electric field shapes, wherein the one pre-defined shape is selected based on the comparison. For example, the pre-defined shape that best matches the displayed therapy tissue region may be selected as the one pre-defined shape. In another method, the therapy tissue region is displayed relative to the graphical electrode representation, and the defined location of the electric field is defined to match the location of the displayed therapy tissue region relative to the graphical electrode representation. 
     In one method, the specified electrode combination is automatically determined based on the selected pre-defined shape and the defined location of the electric field. In this case, the method may further comprise automatically determining a plurality of different combinations of the electrodes based on the selected pre-defined shape and the defined location of the electric field, and serially conveying electrical stimulation energy into the tissue of the patient via the plurality of determined electrode combinations, thereby creating a clinical effect for each of the determined electrode combinations. The method may further comprise assigning a score to each of the determined electrode combinations based on the respective clinical effect, and selecting one of the determined electrode combinations based on the assigned scores. 
     In accordance with a sixth aspect of the present inventions, an external programmer for use with a neurostimulator is provided. The external programmer comprises memory storing a plurality of different pre-defined shapes (e.g., a circular shape and a pear-shape) for an electric field, and a user interface configured for allowing a user to select one of the pre-defined shapes, and for allowing the user to define a location of the electric field relative to a graphical representation of the electrodes. The external programmer further comprises output circuitry configured for communicating with the neurostimulator, processing circuitry configured for determining a combination of the electrodes (which may be fractionalized) based on the one selected shape and defined location of the electric field, and control circuitry configured for instructing the neurostimulator via the output circuitry to convey electrical stimulation energy into the tissue of the patient via the determined electrode combination. The control circuitry may be further configured for programming the neurostimulator with the determined electrode combination. 
     In one optional embodiment, the user interface is further configured for allowing a user to select another one of the plurality of different pre-defined shapes for another electric field, and allowing the user to define a location of the other electric field relative to the graphical representation of the electrodes. In this case, the processing circuitry may be configured for determining the combination of the electrodes based on both the one selected shape and defined location of the electric field and the other selected shape and defined location of the other electric field. In another optional embodiment. the control circuitry is further configured for adjusting an intensity level of the conveyed electrical stimulation energy, wherein a size of the displayed electric field is adjusted in accordance with the adjusted intensity level. 
     The control circuitry may further be configured for instructing a display device to display a representation of the electric field relative to the graphical electrode representation. In this case, the control circuitry may be configured for displaying a therapy tissue region to a user, and the user interface may be configured for allowing a user to compare the displayed therapy tissue region to the plurality of different pre-defined electric field shapes, such that the user may select the one pre-defined shape based on the comparison. In another embodiment, the control circuitry may be configured for displaying the therapy tissue region is displayed relative to the graphical electrode representation, and the user interface may be configured for allowing the user to define the location of the electric field to match the location of the displayed therapy tissue region relative to the graphical electrode representation. 
     In one embodiment, the processing circuitry is configured for automatically determining the electrode combination based on the selected pre-defined shape and the defined location of the electric field. In this case, the processing circuitry may be configured for automatically determining a plurality of different combinations of the electrodes based on the selected pre-defined shape and the defined location of the electric field, and the control circuitry may be configured for serially conveying electrical stimulation energy into the tissue of the patient via the plurality of determined electrode combinations, thereby creating a clinical effect for each of the determined electrode combinations. The processing circuitry may be configured for assigning a score to each of the determined electrode combinations based on the respective clinical effect, and the user interface may be configured for allowing the user to select one of the determined electrode combination based on the assigned scores. 
     Other and further aspects and features of the invention will be evident from reading the following detailed description of the preferred embodiments, which are intended to illustrate, not limit, the invention. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The drawings illustrate the design and utility of preferred embodiments of the present invention, in which similar elements are referred to by common reference numerals. In order to better appreciate how the above-recited and other advantages and objects of the present inventions are obtained, a more particular description of the present inventions briefly described above will be rendered by reference to specific embodiments thereof, which are illustrated in the accompanying drawings. Understanding that these drawings depict only typical embodiments of the invention and are not therefore to be considered limiting of its scope, the invention will be described and explained with additional specificity and detail through the use of the accompanying drawings in which: 
         FIG. 1  is a plan view of a Deep Brain Stimulation (DBS) system constructed in accordance with one embodiment of the present inventions; 
         FIG. 2  is a profile view of an implantable pulse generator (IPG) and a first embodiment of neurostimulation leads used in the DBS system of  FIG. 1 ; 
         FIG. 3  is a profile view of an implantable pulse generator (IPG) and a second embodiment of neurostimulation leads used in the DBS system of  FIG. 1 ; 
         FIG. 4  is a cross-sectional view of one of the neurostimulation leads of  FIG. 3 , taken along the line  4 - 4 ; 
         FIG. 5  is a cross-sectional view of a patient&#39;s head showing the implantation of stimulation leads and an IPG of the DBS system of  FIG. 1 ; 
         FIG. 6  is front view of a remote control (RC) used in the DBS system of  FIG. 1 ; 
         FIG. 7  is a block diagram of the internal components of the RC of  FIG. 6 ; 
         FIG. 8  is a block diagram of the internal components of a clinician&#39;s programmer (CP) used in the DBS system of  FIG. 1 ; 
         FIG. 9  is a plan view of a one embodiment of a programming screen that can be generated by the CP of  FIG. 8 ; 
         FIG. 10  is a plan view of one embodiment of a therapy selection screen that can be generated by the CP of  FIG. 8 ; 
         FIG. 11  is a plan view of a neurostimulation lead implanted in tissue with therapy tissue regions and side-effect tissue regions; 
         FIG. 12  is a plan view of one embodiment of a clinical effects analysis screen that can be generated by the CP of  FIG. 8 ; 
         FIG. 13  is a plan view of a method used by the CP of  FIG. 8  to determine one-half of a target tissue region from a bar map generated in the clinical effects analysis screen of  FIG. 12 ; 
         FIG. 14  is a plan view of a method used by the CP of  FIG. 8  to generate the entire target tissue region from the one-half target tissue region generated in  FIG. 13 ; 
         FIGS. 15 a -15 d    are plan views of another embodiment of a clinical effects analysis screen that can be generated by the CP of  FIG. 8 ; 
         FIG. 16  is a plan view of still another embodiment of a clinical effects analysis screen that can be generated by the CP of  FIG. 8 ; 
         FIG. 17  is a plan view of a method used by the CP of  FIG. 8  to determine one-half of a target tissue region from a bar map generated in the clinical effects analysis screen of  FIG. 16 ; 
         FIG. 18  is a plan view of a method used by the CP of  FIG. 8  to generate the entire target tissue region from the one-half target tissue region generated in  FIG. 17 ; 
         FIG. 19  is a plan view of yet another embodiment of a clinical effects analysis screen that can be generated by the CP of  FIG. 8 ; 
         FIGS. 20 a -20 d    are plan views illustrating a series of steps in generating a volume map in the clinical effects analysis screen of  FIG. 19 ; 
         FIG. 21  is a plan view of one embodiment of an atlas modification screen that can be generated by the CP of  FIG. 8 ; 
         FIGS. 22 a -22 b    are plan views showing an exemplary method used by the CP to modify an atlas via the atlas modification screen of  FIG. 21 ; 
         FIGS. 23 a -23 b    are plan views showing another exemplary method used by the CP to modify an atlas via the atlas modification screen of  FIG. 21 ; 
         FIG. 24  is a plan view showing still another exemplary method used by the CP to modify an atlas via the atlas modification screen of  FIG. 21 ; 
         FIG. 25  is a plan view of one embodiment of an electric field selection screen that can be generated by the CP of  FIG. 8 . 
         FIG. 26  is a plan view of the electric field selection screen of  FIG. 25 , particularly illustrating the user selection of two shapes for an electric field; 
         FIG. 27  is a plan view of the electric field selection screen of  FIG. 25 , particularly showing the movement of a selected electric field shape along a graphical representation of the neurostimulation lead; 
         FIG. 28  is a plan view of the electric field selection screen of  FIG. 25 , particularly illustrating the modification of a user-selected electric field shape; 
         FIG. 29  is a plan view of a program selection screen that can be generated by the CP of  FIG. 8 ; 
         FIG. 30  is a block diagram of an optimization algorithm that can be used by the CP of  FIG. 8  to suggest an optimal electrode configuration for obtaining clinical effects data. 
     
    
    
     DETAILED DESCRIPTION OF THE EMBODIMENTS 
     The description that follows relates to a deep brain stimulation (DBS) system. However, it is to be understood that the while the invention lends itself well to applications in DBS, the invention, in its broadest aspects, may not be so limited. Rather, the invention may be used with any type of implantable electrical circuitry used to stimulate tissue. For example, the present invention may be used as part of a pacemaker, a defibrillator, a cochlear stimulator, a retinal stimulator, a stimulator configured to produce coordinated limb movement, a cortical stimulator, a spinal cord stimulator, peripheral nerve stimulator, microstimulator, or in any other neural stimulator configured to treat urinary incontinence, sleep apnea, shoulder subluxation, headache, etc. 
     Turning first to  FIG. 1 . an exemplary DBS neurostimulation system  10  generally includes at least one implantable stimulation lead  12  (in this case, two), a neurostimulator in the form of an implantable pulse generator (IPG)  14 , an external remote controller RC  16 , a clinician&#39;s programmer (CP)  13 , an External Trial Stimulator (ETS)  20 , and an external charger  22 . 
     The IPG  14  is physically connected via one or more percutaneous lead extensions  24  to the neurostimulation leads  12 , which carry a plurality of electrodes  26  arranged in an array. In the illustrated embodiment, the neurostimulation leads  12  are percutaneous leads, and to this end, the electrodes  26  may be arranged in-line along the neurostimulation leads  12 . In alternative embodiments, the electrodes  26  may be arranged in a two-dimensional pattern on a single paddle lead if, e.g., cortical brain stimulation is desired. As will be described in further detail below, the IPG  14  includes pulse generation circuitry that delivers electrical stimulation energy in the form of a pulsed electrical waveform (i.e., a temporal series of electrical pulses) to the electrode array  26  in accordance with a set of stimulation parameters. 
     The ETS  20  may also be physically connected via the percutaneous lead extensions  28  and external cable  30  to the neurostimulation leads  12 . The ETS  20 , which has similar pulse generation circuitry as the IPG  14 , also delivers electrical stimulation energy in the form of a pulse electrical waveform to the electrode array  26  accordance with a set of stimulation parameters. The major difference between the ETS  20  and the IPG  14  is that the ETS  20  is a non-implantable device that is used on a trial basis after the neurostimulation leads  12  have been implanted and prior to implantation of the IPG  14 , to test the responsiveness of the stimulation that is to be provided. Thus, any functions described herein with respect to the IPG  14  can likewise be performed with respect to the ETS  20 . 
     The RC  16  may be used to telemetrically control the ETS  20  via a bi-directional RF communications link  32 . Once the IPG  14  and stimulation leads  12  are implanted, the RC  16  may be used to telemetrically control the IPG  14  via a bi-directional RF communications link  34 . Such control allows the IPG  14  to be turned on or off and to be programmed with different stimulation parameter sets. The IPG  14  may also be operated to modify the programmed stimulation parameters to actively control the characteristics of the electrical stimulation energy output by the IPG  14 . As will be described in further detail below, the CP  18  provides clinician detailed stimulation parameters for programming the IPG  14  and ETS  20  in the operating room and in follow-up sessions. 
     The CP  18  may perform this function by indirectly communicating with the IPG  14  or ETS  20 , through the RC  16 , via an IR communications link  36 . Alternatively, the CP  18  may directly communicate with the IPG  14  or ETS  20  via an RF communications link (not shown). The clinician detailed stimulation parameters provided by the CP  18  are also used to program the RC  16 , so that the stimulation parameters can be subsequently modified by operation of the RC  16  in a stand-alone mode (i.e.. without the assistance of the CP  18 ). 
     The external charger  22  is a portable device used to transcutaneously charge the IPG  14  via an inductive link  38 . For purposes of brevity, the details of the external charger  22  will not be described herein. Details of exemplary embodiments of external chargers are disclosed in U.S. Pat. No. 6,895,280, which has been previously incorporated herein by reference. Once the IPG  14  has been programmed, and its power source has been charged by the external charger  22  or otherwise replenished, the IPG  14  may function as programmed without the RC  16  or CP  18  being present. 
     Referring to  FIG. 2 . the IPG  14  comprises an outer case  40  for housing the electronic and other components (described in further detail below), and a connector  42  to which the proximal end of the neurostimulation lead  12  mates in a manner that electrically couples the electrodes  26  to the internal electronics (described in further detail below) within the outer case  40 . The outer case  40  is composed of an electrically conductive, biocompatible material, such as titanium, and forms a hermetically sealed compartment wherein the internal electronics are protected from the body tissue and fluids. In some cases, the outer case  40  may serve as an electrode. 
     Each of the neurostimulation leads  12  comprises an elongated cylindrical lead body  43 , and the electrodes  26  take the form of ring electrodes mounted around the lead body  43 . One of the neurostimulation leads  12  has eight electrodes  26  (labeled E 1 -E 8 ), and the other neurostimulation lead  12  has eight electrodes  26  (labeled E 9 -E 16 ). The actual number and shape of leads and electrodes will, of course, vary according to the intended application. 
     In an alternative embodiment illustrated in  FIG. 3 , the electrodes  26  take the form of segmented electrodes that are circumferentially and axially disposed about the lead body  43 . By way of non-limiting example, and with further reference to  FIG. 4 . one neurostimulation lead  12  may carry sixteen electrodes, arranged as four rings of electrodes (the first ring consisting of electrodes E 1 -E 4 ; the second ring consisting of electrodes E 5 -E 8 : the third ring consisting of electrodes E 9 -E 12 ; and the fourth ring consisting of E 13 -E 16 ) or four axial columns of electrodes (the first column consisting of electrodes E 1 , E 5 , E 9 , and E 13 ; the second column consisting of electrodes E 2 , E 6 , E 10 , and E 14 ; the third column consisting of electrodes E 3 , E 7 , E 11 , and E 15 ; and the fourth column consisting of electrodes E 4 , E 8 , E 12 , and E 16 ). 
     Further details describing the construction and method of manufacturing percutaneous stimulation leads are disclosed in U.S. patent application Ser. No. 11/689,918, entitled “Lead Assembly and Method of Making Same.” and U.S. patent application Ser. No. 11/565,547, entitled “Cylindrical Multi-Contact Electrode Lead for Neural Stimulation and Method of Making Same,” the disclosures of which are expressly incorporated herein by reference. 
     As will be described in further detail below, the IPG  14  includes a battery and pulse generation circuitry that delivers the electrical stimulation energy in the form of a pulsed electrical waveform to the electrode array  26  in accordance with a set of stimulation parameters programmed into the IPG  14 . Such stimulation parameters may comprise electrode combinations, which define the electrodes that are activated as anodes (positive), cathodes (negative), and turned off (zero), percentage of stimulation energy assigned to each electrode (fractionalized electrode configurations), and electrical pulse parameters, which define the pulse amplitude (measured in miliiamps or volts depending on whether the IPG  14  supplies constant current or constant voltage to the electrode array  26 ), pulse duration (measured in microseconds), pulse rate (measured in pulses per second), and burst rate (measured as the stimulation on duration X and stimulation off duration Y). The IPG  14  may be capable of delivering the stimulation energy to the array  22  over multiple channels or over only a single channel. 
     Electrical stimulation will occur between two (or more) activated electrodes, one of which may be the IPG case. Simulation energy may be transmitted to the tissue in a monopolar or multipolar (e.g., bipolar, tripolar, etc.) fashion. Monopolar stimulation occurs when a selected one of the lead electrodes  26  is activated along with the case of the IPG  14 , so that stimulation energy is transmitted between the selected electrode  26  and case Bipolar stimulation occurs when two of the lead electrodes  26  are activated as anode and cathode, so that stimulation energy is transmitted between the selected electrodes  26 . Multipolar stimulation occurs when at least three of the lead electrodes  26  are activated, e.g., two as anodes and the remaining one as a cathode, or two as cathodes and the remaining one as an anode. 
     In the illustrated embodiment, IPG  14  can individually control the magnitude of electrical current flowing through each of the electrodes. In this case, it is preferred to have use current generators, wherein individual current-regulated amplitudes from independent current sources for each electrode may be selectively generated. Although this system is optimal to take advantage of the invention, other stimulators that may be used with the invention include stimulators having voltage regulated outputs. While individually programmable electrode amplitudes are optimal to achieve fine control, a single output source switched across electrodes may also be used, although with less fine control in programming. Mixed current and voltage regulated devices may also be used with the invention. 
     Further details discussing the detailed structure and function of IPGs are described more fully in U.S. Pat. Nos. 6,516,227 and 6,993,384, which are expressly incorporated herein by reference. 
     As shown in  FIG. 5 , two percutaneous neurostimulation leads  12  are introduced through a burr hole  46  (or alternatively, two respective burr holes) formed in the cranium  43  of a patient  44 , and introduced into the parenchyma of the brain  49  of the patient  44  in a conventional manner, such that the electrodes  26  are adjacent a target tissue region, the stimulation of which will treat the dysfunction (e.g., the ventrolateral thalamus, internal segment of globus pallidus, substantia nigra pars reticulate, subthalamic nucleus, or external segment of globus paliidus). Thus, stimulation energy can be conveyed from the electrodes  26  to the target tissue region to change the status of the dysfunction. Due to the lack of space near the location where the neurostimulation leads  12  exit the burr hole  46 , the IPG  14  is generally implanted in a surgically-made pocket either in the chest, or in the abdomen. The IPG  14  may, of course, also be implanted in other locations of the patient&#39;s body. The lead extension(s)  24  facilitates locating the IPG  14  away from the exit point of the neurostimulation leads  12 . 
     Referring now to  FIG. 6 , one exemplary embodiment of an RC  16  will now be described. As previously discussed, the RC  16  is capable of communicating with the IPG  14 , CP  18 . or ETS  20 . The RC  16  comprises a casing  50 . which houses internal componentry (including a printed circuit board (PCB)), and a lighted display screen  52  and button pad  54  carried by the exterior of the casing  50 . In the illustrated embodiment, the display screen  52  is a lighted flat panel display screen, and the button pad  54  comprises a membrane switch with metal domes positioned over a flex circuit, and a keypad connector connected directly to a PCB. In an optional embodiment, the display screen  52  has touchscreen capabilities. The button pad  54  includes a multitude of buttons  56 ,  58 ,  60 , and  62 , which allow the IPG  14  to be turned ON and OFF, provide for the adjustment or setting of stimulation parameters within the IPG  14 , and provide for selection between screens. 
     In the illustrated embodiment, the button  56  serves as an ON/OFF button that can be actuated to turn the IPG  14  ON and OFF. The button  58  serves as a select button that allows the RC  16  to switch between screen displays and/or parameters. The buttons  60  and  62  serve as up/down buttons that can actuated to increment or decrement any of stimulation parameters of the pulse generated by the IPG  14 . including pulse amplitude, pulse width, and pulse rate. For example, the selection button  58  can be actuated to place the RC  16  in an “Pulse Amplitude Adjustment Mode,” during which the pulse amplitude can be adjusted via the up/down buttons  60 ,  62 , a “Pulse Width Adjustment Mode.” during which the pulse width can be adjusted via the up/down buttons  60 ,  62 , and a “Pulse Rate Adjustment Mode.” during which the pulse rate can be adjusted via the up/down buttons  60 ,  62 . Alternatively, dedicated up/down buttons can be provided for each stimulation parameter. Rather than using up/down buttons, any other type of actuator, such as a dial, slider bar. or keypad, can be used to increment or decrement the stimulation parameters. Further details of the functionality and internal componentry of the RC  16  are disclosed in U.S. Pat. No. 6,895,280, which has previously been incorporated herein by reference. 
     Referring to  FIG. 7 , the internal components of an exemplary RC  16  will now be described. The RC  16  generally includes a controller/processor  64  (e.g., a microcontroller), memory  66  that stores an operating program for execution by the controller/processor  64 , as well as stimulation parameter sets in a look-up table (described below), input/output circuitry, and in particular, telemetry circuitry  68  for outputting stimulation parameters to the IPG  14  and receiving status information from the IPG  14 , and input/output circuitry  70  for receiving stimulation control signals from the button pad  54  and transmitting status information to the display screen  52  (shown in  FIG. 6 ). As well as controlling other functions of the RC  16 , which will not be described herein for purposes of brevity, the controller/processor  64  generates new stimulation parameter sets in response to the user operation of the button pad  54 . These new stimulation parameter sets would then be transmitted to the IPG  14  (or ETS  20 ) via the telemetry circuitry  68 . Further details of the functionality and internal componentry of the RC  16  are disclosed in U.S. Pat. No. 6,895,280, which has previously been incorporated herein by reference. Notably, while the controller/processor  64  is shown in  FIG. 7  as a single device, the processing functions and controlling functions can be performed by a separate controller and processor. 
     As briefly discussed above, the CP  18  greatly simplifies the programming of multiple electrode combinations, allowing the physician or clinician to readily determine the desired stimulation parameters to be programmed into the IPG  14 , as well as the RC  16 . Thus, modification of the stimulation parameters in the programmable memory of the IPG  14  after implantation is performed by a clinician using the CP  18 , which can directly communicate with the IPG  14  or indirectly communicate with the IPG  14  via the RC  16 . That is, the CP  18  can be used by the physician or clinician to modify operating parameters of the electrode array  26  in the brain. 
     The overall appearance of the CP  18  is that of a laptop personal computer (PC), and in fact, may be implanted using a PC that has been appropriately configured to include a directional-programming device and programmed to perform the functions described herein. Alternatively, the CP  18  may take the form of a mini-computer, personal digital assistant (PDA), smartphone, etc., or even a remote control (RC) with expanded functionality. Thus, the programming methodologies can be performed by executing software instructions contained within the CP  18 . Alternatively, such programming methodologies can be performed using firmware or hardware. In any event, the CP  18  may actively control the characteristics of the electrical stimulation generated by the IPG  14  to allow the optimum stimulation parameters to be determined based on patient response and feedback and for subsequently programming the IPG  14  with the optimum stimulation parameters. 
     Referring to  FIG. 8 . to allow the user to perform these functions, the CP  18  includes a standard user input device  72  (e.g., a keyboard, mouse, joystick, etc.) to allow a clinician to input information and control the process and a display monitor  76  housed in a case, in the illustrated embodiment, the monitor  76  is a conventional screen. Alternatively, instead of being conventional, the monitor  76  may be a digitizer screen, such as touchscreen (not shown), and may be used in conjunction with an active or passive digitizer stylus/finger touch. The CP  18  generally includes a controller/processor  80  (e.g.. a central processor unit (CPU)) and memory  82  that stores a stimulation programming package  84 , which can be executed by the controller/processor  80  to allow the user to program the IPG  14 , and RC  16 . The CP  18  further includes output circuitry  86  for downloading stimulation parameters to the IPG  14  and RC  16  and tor uploading stimulation parameters already stored in the memory  66  of the RC  16 , via the telemetry circuitry  68  of the RC  16 . Notably, while the controller/processor  80  is shown in  FIG. 8  as a single device, the processing functions and controlling functions can be performed by a separate controller and processor. Thus, it can be appreciated that the controlling functions described below as being performed by the CP  18  can be performed by a controller, and the processing functions described below as being performed by the CP  18  can be performed by a processor. 
     Execution of the programming package  84  by the controller/processor  80  provides a multitude of display screens (not shown) that can be navigated through via use of the user input device  72 . These display screens allow the clinician to, among other functions, to select or enter patient profile information (e.g., name, birth date, patient identification, physician, diagnosis, and address), enter procedure information (e.g., programming/follow-up, implant trial system, implant IPG, implant IPG and lead(s), replace IPG, replace IPG and leads, replace or revise leads, explant, etc.), generate a therapeutic map (e.g., body regions targeted for therapy, body regions for minimization of side-effects, along with metrics (e.g.. Unified Parkinson&#39;s Disease Rating Scale (UPDRS)) of success for said targets) of the patient, define the configuration and orientation of the leads, initiate and control the electrical stimulation energy output by the leads  12 , and select and program the IPG  14  with stimulation parameters in both a surgical setting and a clinical setting. Further details discussing the above-described CP functions are disclosed in U.S. patent application Ser. No. 12/501,282, entitled “System and Method for Converting Tissue Stimulation Programs in a Format Usable by an Electrical Current Steering Navigator,” and U.S. patent application Ser. No. 12/614,942, entitled “System and Method for Determining Appropriate Steering Tables for Distributing Stimulation Energy Among Multiple Neurostimulation Electrodes,” which are expressly incorporated herein by reference. 
     The user interface includes a series of programming screens with various control elements that can be actuated to perform functions corresponding to the control elements. In the illustrated embodiment, control elements are implemented as a graphical icon that can be clicked with a mouse in the case of a conventional display device. Alternatively, the display device may have a digitizer screen (e.g.. a touchscreen) that can be touched or otherwise activated with an active or passive digitizer stylus. More alternatively, the control elements described herein may be implemented as a joy stick, touchpad, button pad, group of keyboard arrow keys, mouse, roller ball tracking device, horizontal or vertical rocker-type arm switches, etc., that can be pressed or otherwise moved to actuate the control elements. Alternatively, other forms of entering information can be used, such as textual input (e.g., text boxes) or microphones. 
     In particular, a programming screen  100  can be generated by the CP  18 , as shown in  FIG. 9 . The programming screen  100  allows a user to perform stimulation parameter testing. To this end, the programming screen  100  comprises a stimulation on/off control  102  that can be alternately clicked to turn the stimulation on or off The programming screen  100  further includes various stimulation parameter controls that can be operated by the user to manually adjust stimulation parameters. In particular, the programming screen  100  includes a pulse width adjustment control  104  (expressed in microseconds (ps)), a pulse rate adjustment control  106  (expressed in pulses per second (pps), and a pulse amplitude adjustment control  108  (expressed in milliamperes (mA)). Each control includes a first arrow that can be clicked to decrease the value of the respective stimulation parameter and a second arrow that can be clicked to increase the value of the respective stimulation parameter. The programming screen  100  also includes multipolar/monopolar stimulation selection control  110 , which includes check boxes that can be alternately clicked by the user to provide multipolar or monopolar stimulation. In an optional embodiment, the case  40  of the IPG  14  may be treated as one of the lead electrodes  26 , such that both the case electrode  40  and at least one of the lead electrodes  26  can be used to convey anodic electrical current at the same time. Additionally, the case electrode may be configured with all the programmability of a lead electrode, with full anodic and cathodic fractionalization. 
     The programming screen  100  also includes an electrode combination control  112  having arrows that can be clicked by the user to select one of four different electrode combinations  1 - 4 . Each of the electrode combinations  1 - 4  can be created using a variety of control elements. The programming screen  100  also includes a set of axial electrical stimulation field displacement control elements  116  and a set of axial electrical stimulation field shaping control elements  118 . 
     When any of the axial electrical stimulation field displacement control elements  116  is actuated, control signals are generated in response to which the controller/processor  80  is configured for generating stimulation parameter sets designed to axially displace the locus of the electrical stimulation field relative to the axis of the lead  12 . Preferably, the control signals that are generated in response to the actuation of the axial electrical stimulation field displacement control elements  116  or the alternative control elements are directional, meaning that the locus of the electrical stimulation field will be displaced in a defined direction in response to a continual actuation of a single control element irrespective of the current position of the locus electrical stimulation field locus. When any of the axial electrical stimulation field shaping control elements  118  is actuated, control signals are generated in response to which the controller/processor  80  is configured for generating stimulation parameter sets designed to axially expand or contract the electrical stimulation field relative to its locus. 
     The control elements  116 ,  118  may be continually actuated (i.e., by continuously actuating one of the control elements  116 ,  118 , e.g., by clicking on one of the control elements  116 ,  118  and holding the click (i.e., continuous actuation of the control following the initial “click”), or repeatedly actuating one of the control elements  116 ,  118 , e.g., by repeatedly clicking and releasing one of the control elements  116 ,  118 ) to generate a series of control signals in response to which the controller/processor  80  is configured for generating the plurality of stimulation parameter sets. The output telemetry circuitry  86  is configured for transmitting these stimulation parameters sets to the IPG  14 . 
     Each of the sets of control elements  116 ,  118  takes the form of a double arrow (i.e., two oppositely pointing control element arrows) that can be actuated to modify the electrical stimulation field depending on the mode of operation. For example, an upper arrow control element  116   a  can be clicked to axially displace the locus of the electrical stimulation field (i.e., along the axis of the lead  12 ) in the proximal direction; a lower arrow control element  116   b  can be clicked to axially displace the locus of the electrical stimulation field (i.e., along the axis of the lead  12 ) in the distal direction; a lower arrow control element  118   a  can be clicked to axially contract the electrical stimulation field about its locus, and an upper arrow control element  118   b  can be clicked to axially expand the electrical stimulation field about its locus. 
     The locus of the electrical stimulation field may be displaced, e.g., by gradually “steering” or shifting electrical current between electrodes in a single timing channel. For example, the locus of the electrical stimulation field can be gradually displaced axially in the distal direction along the lead  12  by gradually including electrodes in a stimulating electrode group and gradually excluding other electrodes from the stimulating electrode group in the single timing channel. 
     Although the programming screen  100  illustrates only one neurostimulation lead  12  with electrodes arranged in only one dimension, thereby allowing the electrical current to only be steered in one dimension, it should be appreciated that the programming screen  100  may additionally illustrate the other neurostimulation lead  12 , thereby arranging the electrodes in two dimensions and allowing the electrical current to be steered in two dimensions. In this case, using appropriate control elements (e.g., left and right arrows), the locus of the electrical stimulation field can be displaced in the transverse direction (perpendicular to the axial direction, and in this case, left or right) and/or the electrical stimulation field can be expanded or contracted in the transverse direction. Of course, the electrodes can be arranged in three-dimensions (e.g., by arranging three neurostimulation leads in three-dimensions or by using electrodes on a single neurostimulation lead that are arranged in three-dimensions, e.g., the segmented neurostimulation leads described in U.S. Provisional Patent Application Ser. No. 61/374,879), in which case, the electrical current can be steering in three-dimensions. 
     Further details discussing different techniques for modifying an electrical stimulation field is disclosed in U.S. Provisional Patent Application 61/374,879, entitled “User Interface for Segmented Neurostimulation Leads,” which is expressly incorporated herein by reference, In an optional embodiment where the neurostimulation lead  12  with segmented electrodes  26  (see  FIG. 3 ) are used, additional control elements can be provided to circumferentially displace the locus of the electrical stimulation field, circumferentially contract or expand the electrical stimulation field, radially displace the locus of the electric field, or radially contract or expand the electrical stimulation field, as disclosed in U.S. Provisional Patent Application 61/374,879. 
     The programming screen  100  displays three-dimensional graphical renderings of the lead  12 ′ and electrodes  26 ′. In an optional embodiment, iconic control elements  120  are graphically linked to the three-dimensional electrode renderings  26 ′. Continual actuation of the control elements  120  generates control signals that prompt the controller/processor  80  to generate stimulation parameters designed to modify the electrical stimulation field, which stimulation parameters are then transmitted from the output circuitry  86  of the CP  18  to the IPG  14 . In the illustrated embodiment, each of the control elements  120  has an up arrow and a down arrow that can be respectively actuated (e.g., by clicking) to respectively increase or decrease the electrical current flowing through the electrode  26  corresponding to the graphical electrode rendering  26 ′ to which the actuated control element  120  is graphically linked. 
     Actuation of any of the control elements  120  essentially steers electrical current from other active electrodes to the electrode associated with the actuated control element  120  or from the electrode associated with the actuated control element  120  to other active electrodes. In this manner, the locus of the electrical stimulation field can be displaced, the shape of the electrical stimulation field can be modified, and if two separate electrical stimulation fields current exist, electrical current can be shifted from one of the electrical stimulation fields (effectively decreasing its size) to another of the electrical stimulation fields (effectively increasing its size). 
     The control element  120  also includes an indicator  122  that provides an indication of the amount of electrical current flowing through each of the electrodes  26  in terms of a fractionalized current value. The indicators  122  may perform this function when the respective control elements  120  are actuated or when the axial electrical stimulation field displacement control elements  116  and axial electrical stimulation field shaping control elements  118  are actuated. 
     The programming screen  100  displays the three-dimensional graphical renderings of the lead  12 ′ and electrodes  26 ′ in registration with anatomical regions of interest, and in particular, a therapy tissue region  124 , the stimulation of which is known or believed to provide the needed therapy to the patient, and a side-effect tissue region  126 , the stimulation of which is known or believed to provide an undesirable side-effect for the patient. The anatomical regions of interest may be anatomical structures, the boundaries of which are naturally defined, or may be arbitrary volumes of interest known to result in therapy or a side-effect when stimulated. In the illustrated embodiment, the anatomical regions of interest are obtained from a generally available atlas. In the illustrated embodiment, the anatomical regions of interest are shown as being two-dimensional, although in other embodiments, the anatomical regions of interest may be three-dimensional in nature. 
     Based on the current stimulation parameter set, the CP  18  may estimate of a resulting region of tissue activation (RTA)  128 , which can be displayed on the programming screen  100  with the graphical lead  12 ′ and anatomical regions of interest  124 ,  126 . Further details discussing technique for computing the estimate of a RTA  128  are disclosed in A. M. M. Frankemolle, et al.,  Reversing Cognitive - Motor Impairments in Parkinson&#39;s Disease Patients Using a Computational Modelling Approach to Deep Brain Stimulation Programming.  Brain 2010; pp. 1-16). which is expressly incorporated herein by reference. 
     Alternatively, instead of computing and displaying a RTA, the CP  18  may compute an electric field (not shown) from the current stimulation parameter set. which may be displayed relative to the graphical lead  12 ′ and anatomical regions of interest  124 ,  126 . In the illustrated embodiment, although the graphical lead  12 ′, anatomical regions of interest  124 ,  126 , and the RTA  128  are displayed in an oblique view, they can be alternatively displayed In any one or more of traditional planes of section (e.g., axial, coronal, and sagittal. 
     Most pertinent to the present inventions, execution of the programming package  84  provides a more intuitive user interface that allows a user to readily determine the extent that to which specified electrodes influence one or more clinical effects (e.g., a therapeutic effect and/or side-effect), modify anatomical regions of interest (e.g., a therapy tissue region and/or a side-effect tissue region) to be specific to the patient, and/or matching a electric field, and thus the electrode combination that best generates the electric field, to a therapy tissue region. To this end, the user interface allows the user to select one or more brain disorders to be treated ( FIG. 10 ), perform a clinical analysis to determine the extent to which each of the electrodes  26  influences anatomical regions of interest ( FIGS. 11-12, 15-16, and 19-20 ). determine the shape and/or boundaries of target and non-target tissue regions ( FIGS. 13-14 and 17-18 ). optionally modify the shape and/or location of anatomical regions of interest ( FIGS. 21-24 ), determining the shape of the electric field that best matches the target tissue region(s) ( FIGS. 25-28 ), determining the program that best emulates the shape of the electric field ( FIG. 29 ). and programming the IPG  14 /RC  16  with the selected program. 
     As shown in  FIG. 10 , a therapy selection screen  200 , which allows a user to select one or more brain disorders to be treated, can be initially generated by the CP  18 . In particular, the therapy selection screen  200  includes graphical controls in the form of a series of disorder boxes  202   a ,  202   b ,  202   c  that can be clicked to select the brain disorder to be treated. In the illustrated embodiment, the disorder box  202   a  can be clicked to treat Parkinson&#39;s Disease, the disorder box  202   b  can be clicked to treat Essential Tremor, and the disorder box  202   c  can be clicked to treat Dystonia. Additional disorder boxes may be displayed in the therapy selection screen  200 , so that other types of brain disorders can be treated. Default stimulation parameters, and in this case, a default pulse width and pulse rate, for each disorder to be treated are shown below the respective disorder box  202 . In the illustrated embodiment, a default pulse width of 60 μs and a default pulse rate of 130 Hz is shown for treatment of the Parkinson&#39;s Disease, a default pulse width of 120 μs and a default pulse rate of 130 Hz is shown for the treatment of Essential Tremor, and a default pulse width of 250 μs and a default pulse rate of 130 Hz is shown for the treatment of Dystonia. The default pulse width and default, pulse rate, as well as the pulse amplitude, can be varied by the user using the programming screen  100 . More than one of the disorder boxes can be clicked to treat multiple brain disorders. The therapy selection screen  200  further includes a next button  204  that can be clicked to continue to the next screens described below. 
     Significantly, the CP  18  can be used to instruct the IPG  14  to serially convey electrical stimulation energy into the tissue via different combinations of the electrodes  26 . thereby creating one or more clinical effects for each of the different electrode combinations. For example, assuming that a neurostimulation lead  12  is implanted in tissue containing a first therapy region TH 1  (e.g., one the stimulation of which alleviates or eliminates the symptoms of Parkinson&#39;s Disease), a second therapy region TH 2  (e.g., one the stimulation of which alleviates or eliminates the symptoms of Dystonia), a first side-effect region SE 1  (e.g., one the stimulation of which causes nausea), and a second side-effect region SE 2  (e.g., one the stimulation of which causes headache), as shown m  FIG. 11 , conveyance of electrical stimulation energy via different combinations of the electrodes will cause either a therapeutic effect, a side-effect, or both. 
     The CP  18  quantifies the influence of each of the different electrode combinations on the clinical effects. For example, if electrode E 1  is activated to convey electrical stimulation energy, it may be concluded that this electrode somewhat influences the side-effect associated with the first side-effect region SE 1 . If electrode E 2  is activated to convey electrical stimulation energy, it may be concluded that this electrode somewhat influences the therapeutic effect associated with the first therapy region TH 1  and the side-effect associated with the first side-effect region SE 1 . If electrode E 3  is activated to convey electrical stimulation energy, it may be concluded that this electrode highly influences the therapeutic effect associated with the first therapy region TH 1 . If electrode E 4  is activated to convey electrical stimulation energy, it may be concluded that this electrode highly influences therapeutic effects associated with the first and second therapy regions TH 1 , TH 2 . If electrode E 5  is activated to convey electrical stimulation energy, it may be concluded that this electrode somewhat influences a side-effect associated with the second side-effect region SE 2  and therapeutic effects associated with the first and second therapy regions TH 1 , TH 2 . If any of electrodes E 6 -E 8  is activated to convey electrical stimulation energy, it may be concluded that these electrodes highly influence a side-effect associated with the second side effect region SE 2 . 
     In the preferred embodiment, the intensity level of the electrical stimulation energy conveyed via each electrode combination is incrementally varied, such that the influence by a specific electrode combination on the clinical effects can be determined by the CP  18  for each of the different intensity levels. The influence by a specific electrode combination on the clinical effects can be determined by the CP  18 , e.g., based on clinical information entered by the user. For example, as described in further detail below, the user may enter into the CP  18  the intensity level at which the patient experiences a therapeutic effect or a side-effect for the specific electrode combination. Alternatively, the influence by a specific electrode combination on the clinical effects can be determined by the CP  18 , e.g.. based on monitored clinical information automatically provided to the CP  18  from monitoring circuitry (not shown). 
     As will be described in further detail below with respect to various embodiments, once the influences of each electrode combination on the clinical effects have been determined, the CP  18  can then generate and display graphical indications of these determined influences, such that the user can determine an extent to which each of the different electrode combinations influences the clinical effects. For the purposes of this specification, the term “graphical” means a textual or non-textual representation. Although the embodiments described herein display non-textual representations of the determined influences, which provides a readily understandable visual from which the user may determine the extent to which each of the different electrode combinations influences the clinical effects, textual representations of the determined influences can be used in addition to, or alternative, to the non-textual graphical indications of the determined influences. 
     In one embodiment shown in  FIG. 12 , a clinical effect analysis screen  300  allows a user to readily determine the extent to which each of the different electrode combinations influences the clinical effects. In particular, the clinical effect analysis screen  300  includes an intensity level adjustment control  302 , which includes an upper arrow  302   a  that can be clicked to increase the intensity value of the electrical stimulation energy conveyed via a specified electrode combination, and a lower arrow  302   b  that can be clicked to decrease the intensity value of the electrical stimulation energy conveyed via a specified electrode combination. The intensity level adjustment control  302  also includes an indicator  302   c  that provides an indication of the intensity of the conveyed electrical stimulation energy, and in the illustrated embodiment, the amount of electrical current flowing through a specified electrode combination in miiliamperes. In the illustrated embodiment, the range of intensity values that can be selected is 0-5 mA in one milliamphere increments, although in other embodiments, the range of intensity values may be larger or smaller, or have a higher or lower resolution. The pulse width and pulse rate of the conveyed electrical stimulation energy will correspond to the default parameters of the disorder selected to be treated in the therapy selection screen  200 . In an optional embodiment, the clinical effect analysis screen  300  may include a pulse width adjustment control and a pulse rate adjustment control (not shown) similar to the adjustment controls  104  and  106  described above with respect to  FIG. 9 . so that the pulse width and/or pulse rate of the conveyed electrical stimulation energy may be adjusted from their default values. 
     The clinical effect analysis screen  300  also includes a graphical representation of the neurostimulation lead  12 ′ and corresponding electrodes  26 ′. In the illustrated embodiment, only the graphical representation for one neurostimulation lead  12 ′ having electrodes E 1 -E 8  is displayed, although graphical representations for multiple neurostimulation leads  12  or alternative neurostimulation leads (e.g., the segmented neurostimulation lead illustrated in  FIG. 3 ) can be displayed. 
     The clinical effect analysis screen  300  also includes an electrode selection control  304  that can be used to select the specific electrode combination to be currently tested (i.e., the specific electrode combination through which the electrical stimulation energy will flow). In the illustrated embodiment, each electrode combination has a single electrode. To this end, the electrode selection control  304  includes an upper arrow  304   a  that can be clicked to increase the index number of the electrode  26 , and a lower arrow  304   b  that can be clicked to decrease the index number of the electrode  26 . The electrode selection control  304  also includes an indicator  304   c  that provides an indication of the selected electrode  26 . In the illustrated embodiment, electrical stimulation energy is conveyed through each selected electrode  26  in a monopolar manner. 
     The clinical effect analysis screen  300  further includes clinical information entry buttons  306  that allows the user to enter clinical Information, and in this embodiment, a therapeutic effect trigger button  306   a  that can be actuated when the patient experiences a therapeutic effect, and a side-effect trigger button  306   b  that can be actuated when the patient experiences a side-effect. Verbal feedback from the patient may prompt the user to actuate either of the clinical information entry buttons  306 . A therapeutic effect may be considered to be a mitigation of a symptom (or a component of the symptom) caused by a disorder, whereas a side-effect can be considered a symptom (or a component of the symptom) of the electrical stimulation. The CP  18  will be capable of determining the influence of each electrode  26  on the therapeutic and side-effects based on the clinical information entered by the user via the clinical information entry buttons  306 . 
     In this embodiment, the CP  18  quantifies the influence of each electrode  26  on the therapeutic effect by determining the range of incremental intensity levels at which a metric of a therapeutic effect occurs based on clinical information entered by the user via the clinical information entry buttons  306 , and further determining the incremental intensity level at which a metric of a side-effect initially occurs. In this embodiment, the metric of the therapeutic effect is an absolute metric, and in particular, whether the perception threshold of the therapeutic effect has been readied or exceeded, and the metric of the side-effect is also an absolute metric, and in particular, whether the perception threshold of the therapeutic effect has been reached or exceeded. 
     In the illustrated embodiment, for each activated electrode, the intensity level adjustment control  302  can be manipulated to incrementally increase the intensity level of the electrical stimulation energy, and at each intensity level, the patient may provide feedback as to whether a therapeutic effect or a side-effect is experienced. For example, for electrode E 1 , the intensity level of the electrical stimulation energy can be incrementally increased, with the patient providing feedback at each of the incremental intensity levels; for electrode E 2 , the intensity level of the electrical stimulation energy can be incrementally increased, with the patient providing feedback at each of the incremental intensity levels; and so on. 
     Thus, at each intensity level for each activated electrode, the user may actuate the therapeutic effect trigger button  306   a  if the therapeutic effect is perceived at all by the patient, and may actuate the side-effect trigger button  306   b  if a side-effect is perceived at all by the patient, such that the CP  18  may determine the range of intensity levels at which the perception threshold of the therapeutic effect is met or exceeded and the Intensity level at which the perception threshold of the side-effect is initially met or exceeded for each activated electrode. Preferably, in the case where the patient has multiple disorders to be treated, the user will actuate the therapeutic effect trigger button  306   a  if a therapeutic effect associated with any of the multiple disorders is perceived, even though a therapeutic effect associated with other multiple disorders may not be perceived. 
     In other embodiments, the metric of the therapeutic effect may be, e.g., whether a relative level (e.g., a particular comfort level) of the therapeutic effect has been reached or exceeded, and the metric of the side-effect may be, e.g.. whether a relative level (e.g., an annoyance level or an intolerable level) has been reached or exceeded. As will be described in other embodiments below, the metric of the therapeutic effect and/or side-effect may take the form of a score that can be separately assigned to a therapeutic effect or side-effect or a wellness score that takes into account both the therapeutic effect or the side-effect. 
     Based on the clinical information entered by the user (in this embodiment, by pushing the therapeutic effect trigger button  306   a  or the side-effect trigger button  306   b  at the appropriate times), the CP  13  may determine the highest intensity level at which the therapeutic effect occurs prior to the initial occurrence of a side-effect. The CP  18  may then graphically generate and display this information in the form of a bar map  308  having a plurality of bars  310 , each of which indicates for each of the electrodes E 1 -E 8  the highest intensity level at which a therapeutic effect occurs prior to the initial occurrence of the side-effect. The horizontal axis of the bar map represents intensity level in increments of one milliamp here, and the vertical axis of the bar map represents the electrode number. 
     In the case where there is at least one intensity level at which the therapeutic effect occurs prior to the initial occurrence of a side-effect, the bar  310  will be a particular color (e.g., green) indicating the range of the intensity levels at which the therapeutic effect occurs. A first tick  312  (e.g., green color) can be placed at the beginning of the bar  310 , indicating the intensity level at which the therapeutic effect initially occurs, and a second tick  314  (e.g., red color) can be placed on the bar  310 , indicating the intensity level at which the side-effect initially occurs, in the case where there is no intensity level at which the therapeutic effect occurs prior to the initial occurrence of the side-effect (i.e., the side-effect occurs prior to the therapeutic effect). In this case where an electrode has not been tested, a question mark “?” is displayed next to that electrode 
     For example, as shown in  FIG. 12  and with further reference to  FIG. 11 . only a side-effect tick  314  is displayed adjacent electrode E 1 , Indicating that a side-effect was perceived prior to a therapeutic effect. Viewing this, a user may understand electrode E 1  to highly influence a side-effect region without influencing a therapeutic effect at all, which corresponds to electrode E 1  being partially contained in the first side-effect region SE 1 . The relatively short bar  310  displayed adjacent electrode E 2  (in the range of 1 mA-2 mA) indicates to the user that electrode E 2  somewhat influences a therapeutic effect and a side-effect, which corresponds to electrode E 2  being between the first therapy region TH 1  and the first side-effect region SE 1 . The relatively long bar  310  displayed adjacent electrode E 3  (in the range of 1 mA-4 mA) indicates to the user that electrode E 3  highly influences a therapeutic effect, which corresponds to electrode E 3  being fully within the first therapy region TH 1 . The longer bar  310  displayed adjacent electrode E 4  (in the range of 1 mA-5 mA) indicates to the user that electrode E 4  influences a therapeutic effect the most out of all of the electrodes, which corresponds to electrode E 4  being in the center of the first therapy region TH 1 . The relatively moderate length bar  310  displayed adjacent electrode E 5  (in the range of 1 mA-3 mA) indicates to the user that electrode E 5  somewhat influences a therapeutic effect and a side effect, which corresponds with electrode E 5  being partially contained in the first and second therapy regions TH 1 , TH 2 , and near the second side-effect region SE 2 . Only a side-effect tick  314  is displayed adjacent electrode E 6 , indicating that electrode E 6  to highly influence a side-effect region without influencing a therapeutic effect at all, which corresponds to electrode E 6  being contained in the second side-effect region SE 1 . The question marks adjacent electrodes E 7  and E 8  have not been tested, presumably by choice of the user based on the fact that the therapeutic effect substantially diminished at electrode E 6 . 
     Although this embodiment has been described as activating each of the electrodes E 1 -E 8  to either an “on” state (100% of the stimulation energy is provided by the electrode) or an “off state” (0% of the stimulation energy is provided by the electrode), in effect, allowing the electrodes to be sequentially turned on and off up or down the neurostimulation lead  12 , electrical current can be steered along the neurostimulation lead  12 , such that a plurality of the electrodes can have fractionalized current values. For example, electrical current can be steered up or down the neurostimulation lead  12  in 10% increments by, e.g., clicking the up and down arrows of a control mechanism similar to the electrode selection control  304 . 
     For example, the process may start with 100% of the electrical current at electrode E 1 , then 90% of the electrical current at electrode E 1  and 10% of the electrical current at electrode E 2 , then 80% of the electrical current at electrode E 1  and 20% of the electrical current at electrode E 2 . and so forth, until a sufficient number of electrodes have been tested. At each fractionalized electrode combination, the user may incrementally increase the intensity level of the stimulation energy in the manner discussed above, so that clinical information can be obtained for each fractionalized electrode combination. A bar map can be generated in the same manner discussed above, with the exception that there will be many more bars (one for each fractionalized electrode combination). 
     In any event, with knowledge that electrode E 4  and the adjacent electrodes influence a therapeutic effect, the user may accordingly program the IPG  14  with the appropriate electrode combination. In one embodiment, the CP  18  dynamically generates and displays the bar map  308  as the user enters the clinical information via the clinical trigger buttons  306 . In an alternative embodiment, the CP  18  generates and displays the bar map  308  only after the user has entered all of the clinical information necessary to complete the bar map  308 , e.g., when prompted by the user via a control button (not shown). The bar map  308  is preferably stored in memory  82  for use in a subsequent programming session, which may be fully manually performed by the user or may be automated by the CP  18 . Optionally, the bar map  308  may be displayed and stored in memory  82  for other purposes For example, the bar map  308  may be displayed in a report or on another device, in a database (e.g., for population analysis), or in a computer file that could be used by another application. 
     The clinical effect analysis screen  300  further includes a disorder treatment indicator  316  that provides an indication to the user of the current disorder that is being treated (i.e., the disorder selected in the therapy selection screen  200  illustrated in  FIG. 10 ). This indicator can be stored with the bar map  308  in memory  82 , such that the user may knows the treated disorder to which the bar map  308  corresponds when subsequently recalled from memory  82 . It should also be appreciated that if multiple disorders are treated, several bar maps  308  may be generated, displayed, and stored in memory, one bar map  308  for each disorder to be treated. For example: after generating, displaying, and storing a bar map  308  for one disorder, the user can return to the therapy selection screen  200 , select another disorder via the disorder boxes  202 , and then go to the clinical effects analysis screen  300  to prompt the CP  18  to generate, display, and store another bar map  308  for the new disorder to be treated. 
     In an optional embodiment, the bar map  308  is used by the CP  18  to define and display a target tissue region for stimulation. In particular, as shown in  FIG. 13 , the CP  18  may automatically define a line  318 ( 1 ) that connects relevant points  320  within the bars  310  of the bar map  308 . In the illustrated embodiment, these points  320  are located halfway between the initial intensity levels of the therapeutic effects (to the extent that there is a therapeutic intensity level) and the side-effect ticks  314  indicated in the respective bars  310  of the bar map  308 . 
     The CP  18  may then smooth the line  318 ( 1 ) and revolve it around a vertical axis  322  defined by the electrodes to create a bi-laterally symmetrical target tissue region  324 ( 1 ), as shown in  FIG. 14 . which can be displayed to the user to aid in programming the IPG  14 . In the case, where a three-dimensional target tissue region is generated and displayed, the line  38 ( 1 ) is revolved around the vertical axis  322  of the electrodes to define a three-dimensional volume. Although the target tissue region  324  may not identically match the therapy regions TH 1 , TH 2  illustrated in  FIG. 11 . it still provides a suitable visual guide for the user to facilitate the programming of the IPG  14  with one or more effective electrode combinations. 
     In alternative embodiments, the connecting points  320  may be located at other locations in the bar map  308 , such as, e.g., at the end of the bars  310  (i.e., at the highest intensity levels of the therapeutic effect) or three-quarters between the initial intensity levels of the therapeutic effects (to the extent that there is a therapeutic intensity level) and the side-effect ticks  314  indicated in the respective bars  310  of the bar map  308 . In these cases, the CP  18  may automatically define line  318 ( 2 ) and  318 ( 2 ) that connect the relevant points  320  within the bars  310  of the bar map  308 , smooth the lines  318 ( 2 ) and  318 ( 3 ), and revolve them around the vertical axis  322  defined by the electrodes to respectively create bi-laterally symmetrical target tissue regions  324 ( 2 ) and  324 ( 3 ), as shown in  FIG. 14 . 
     Notably, the line  318 ( 1 ) and the corresponding target tissue region  324 ( 1 ) provides the least aggressive therapy (e.g., when the patient is asleep), the line  318 ( 2 ) and the corresponding target tissue region  324 ( 2 ) provides moderately aggressive therapy (e.g., when the patient is talking), and the line  318 ( 3 ) and the corresponding target tissue region  324 ( 3 ) provides the most aggressive therapy (e.g., when the patient is walking). A control (not shown) can be provided, which can be actuated by the user to select a “low” setting that prompts the CP  18  to create target tissue regions having the least aggressive therapy, a “medium” setting that prompts the CP  18  to create target tissue regions having a moderately aggressive therapy, and a “high” setting that prompts the CP  18  to create target tissue regions having the most aggressive therapy. 
     Although the previous embodiment has been described in the context of a neurostimulation lead  12  having ring electrodes  26  (e.g., the neurostimulation lead  12  illustrated in  FIG. 2 ), a neurostimulation lead  12  having segmented electrodes  26  can be used (e.g., the neurostimulation lead  12  illustrated in  FIG. 3 ). 
     For example, referring to  FIGS. 15 a -15 d   , a clinical effect analysis screen  400  allows a user to readily determine the extent to which each of the different electrode combinations influences the clinical effects. The clinical effect analysis screen  400  is similar to the clinical effect analysis screen  300  illustrated in  FIG. 12 . with the exception that a bar map  308  is generated and displayed for the electrode segments  26  on one side of the neurostimulation lead  12  (i.e., a first bar map  308   a  for electrodes E 1 , E 5 , E 9 , and E 13  ( FIG. 15 a   ); a second bar map  308   b  for electrodes E 2 , E 6 , E 10 , and E 14  ( FIG. 15 b   ); a third bar map  308   c  for electrodes E 3 , E 7 , E 11 , and E 15  ( FIG. 15 c   ); and a fourth bar map  308   d  for electrodes E 4 , E 8 , E 12 , and E 16  ( FIG. 15 d   )). In the same manner discussed above with respect to the clinical effect analysis screen  300 , the intensity level of the electrical stimulation energy conveyed through each electrode can be incrementally increased using the intensity level adjustment control  302 , and the clinical information can be gathered via the clinical effect trigger buttons  306 , such that the bar maps  308  can be generated. However, the clinical effect analysis screen  400  includes a view rotation button  424  that rotates the view of the electrodes  26  and corresponding bar map  308  in a carousel-like fashion. In an optional embodiment where the generation and display of a target tissue region is desired, the CP  18 , for each bar map  308 , may define a line that connects relevant points within the bars  310 , such that a total of four lines spaced  90  degrees from each other are defined. In this case, the CP  18  may conform a three-dimensional surface to the lines to create a three-dimensional target tissue region. 
     As briefly discussed above, instead of entering clinical information indicating whether or not a therapeutic effect or side-effect has been perceived by the patient, as score can be assigned to a therapeutic effect or even a side-effect to allow the CP  18  to better quantify the clinical effects. The use of scores to aid in determining clinical effects is particularly useful when multiple disorders are being treated for the patient. 
     For example, referring to  FIG. 16 , a clinical effect analysis screen  500  is similar to the clinical effect analysis screen  300  described above, with the exception that, instead of having clinical trigger buttons  306  that allow the user to enter when a therapeutic effect or side-effect is perceived,, this screen includes score entry boxes  506 , and in particular, a therapeutic score box  506   a  and a side-effect score box  506   b . that allows the user to enter scores for the therapeutic effect or side-effect. Thus, for each incremental intensity level of the electrical stimulation energy conveyed via the currently selected electrode, the user may enter a score for a therapeutic effect (if any) in the therapeutic score box  506   a . and a score for a side-effect (if any) in the side-effect score box  506   b.    
     Of course, a different means for entering scores into the CP  18  and displaying the scores to the user other than text entry boxes can be used, controls similar to the intensity level adjustment control  302  and electrode selection control  304 . Whereas the user preferably incrementally increased the intensity level of the stimulation energy via the intensity level adjustment control  302  until a side-effect was perceived (i.e., up until the perception threshold of the side-effect is met or exceeded) in the clinical effects analysis screen  300  above, when using the clinical effect analysis screen  500 , as long as a therapeutic effect is perceived, the user preferably incrementally increases the intensity level of the stimulation energy via the intensity level adjustment control  302  until the side-effect is intolerable, so that the side-effect can be fully determined by the CP  18 . 
     The user may enter the score into the therapeutic score box  506   a  as a relative improvement in a symptom, with 0% representing no improvement in the symptom, and 100% representing total elimination of the symptom as if there were no disease state. In contrast to the clinical effect analysis screen  300  of  FIG. 12  where a bar map  308  is generated for each of the disorders, the clinical effect analysis screen  500  generates a composite score from the individual scores corresponding to the respective disorders, so that one bar map is generated for the multiple disorders. For example, at a particular intensity level for a particular electrode, if a score of 10% is entered for Parkinson&#39;s Disease, and a score of 40% is entered for Essential Tremor, the CP  18  will determine the composite score to be 25%. In an optional embodiment, the disorders may be weighted, such that the scores for one disorder affect the composite score more than the scores for another disorder. For example. if Parkinson&#39;s Disease is weighted twice as much as Essential Tremor, the composite score in the exemplary case may be 35% instead of 25%. If multiple side-effects are perceived by the patient, the user may enter the worst-case score into the side-effect score box  506   b . For example, if two side-effects are experienced by the patient (e.g., nausea and slurred speech), and one side-effect is really bad, whereas the other side-effect is minimal, the score for the one side-effect can be entered into the side-effect score box  506   b , whereas the score for the other side-effect can be ignored In an alternative embodiment, a general wellness score box (not shown) can be used to enter a wellness score that takes into account the therapeutic effect and side-effect resulting from the electrical stimulation energy at each incremental intensity level. 
     In this embodiment, the CP  18  graphically generates and displays this information in the form of bar map  508  for the electrodes E 1 -E 8 . The bar map  508  includes a sets of vertical bars  510 , each set being displayed on a line “Th” next to the electrode that is currently selected for testing. Each of the vertical bars  510  indicates the relative level (in this case, a score) of the therapeutic effect at each incremental intensity level for each of the electrodes E 1 -E 8 . The height of each vertical bar  510  is proportional to the score that it indicates, such that as the score increases, the height of the corresponding vertical bar  510  increases. In the case where there is no therapeutic effect at an incremental intensity level, no bar is generated and displayed. 
     The bar map  508  also includes horizontal bars  512 , each of which is displayed on a line “SE” next to the electrode that is currently selected for testing. Each of the horizontal bars  512  is graduated with different shades to indicate the relative level (in this case, a score) of the side-effect at the incremental intensity levels for each of the electrodes E 1 -E 8 . The darkness of the shades in each of the horizontal bars  510  is proportion to the score that It indicates, such that as the score increases, the shade becomes darker. Thus, the beginning of where the shading in the horizontal bar  510  appears indicates the beginning of the side-effect (i.e., when the side-effect is initially perceived), which increases in darkness, with a black shading indicating that the side-effect has become intolerable. In this case where there is no side-effect at an incremental intensity level, no shade is displayed. In an optional embodiment, the bar map  508  further includes an intolerable side-effect indicator (not shown) that can be generated and displayed at the respective incremental intensity level that it is perceived. To this end, the clinical effect analysis screen  500  may include a trigger button (not shown) that can be actuated by the user to indicate when a side-effect is intolerable to the patient. 
     Notably, because the pulse width and pulse rate of stimulation energy used to treat different disorders will differ from each other, the user will typically test all of the electrodes for one disorder before testing all of the electrodes for another disorder. For example, after testing all of the relevant electrodes and entering the clinical information for one disorder, the user can return to the therapy selection screen  200 , select another disorder via the disorder boxes  202 , and then go to the clinical effects analysis screen  500  to test the relevant electrodes and enter the clinical information for the other disorder. 
     In the example illustrated in  FIG. 16  and with further reference to  FIG. 11 , no vertical bar  510  and a moderate intensity shading for the horizontal bar  512  is displayed adjacent electrode E 1 , indicating to the user that electrode E 1  highly influences a side-effect region without influencing a therapeutic effect at all, which corresponds to electrode E 1  being partially contained in the first side-effect region SE 1 . The highest score vertical bar  510  displayed adjacent electrode E 2  is 40%; however, the side-effect. is initially perceived before that vertical bar  510 , indicating to the user that electrode E 2  somewhat influences a therapeutic effect and a side-effect. which corresponds to electrode E 2  being between the first therapy region TH 1  and the first side-effect region SE 1 . The highest score vertical bar  510  displayed adjacent electrode E 3  is 80%, with the side-effect being initially perceived after this vertical bar  510 , indicating that electrode E 3  highly influences a therapeutic effect, which corresponds to electrode E 3  being fully within the first therapy region TH 1 . The highest score vertical bar  510  displayed adjacent electrode E 4  is 100%, with the side-effect never being perceived at all, indicating that electrode E 4  highly influences a therapeutic effect, which corresponds to electrode E 4  being in the center of the first therapy region TH 1 . The highest score vertical bar  510  displayed adjacent electrode E 5  is 40%; however, the side-effect is initially perceived before that vertical bar  510 , indicating to the user that electrode E 5  somewhat influences a therapeutic effect and a side-effect, which corresponds with electrode E 5  being partially contained in the first and second therapy regions TH 1 , TH 2 , and near the second side-effect region SE 2 . No vertical bar  510  and a moderate intensity shading for the horizontal bar  512  is displayed adjacent electrode E 6 , indicating to the user that electrode E 6  highly influences a side-effect region without influencing a therapeutic effect at all, which corresponds to electrode E 6  being contained in the second side-effect region SE 1 . The question marks adjacent electrodes E 7  and E 8  have not been tested, presumably by choice of the user based on the fact that the therapeutic effect diminished at electrode E 6 . 
     In an optional embodiment, the bar map  508  is used by the CP  18  to define and display a target tissue region for stimulation. In particular, as shown in  FIG. 17 , the CP  18  may automatically define a line  518  that connects relevant points  520  within the bar map  508 . In the illustrated embodiment, each of the points  520  are located in the gap between the incremental intensity level corresponding to the highest score vertical bar  510  and the incremental intensity level at which a side-effect is initially perceived for the respective electrode. The CP  18  may then smooth the line  518  and revolve it around a vertical axis  522  defined by the electrodes to create a bi-laterally symmetrical target tissue region  524 , as shown in  FIG. 18 , which can be displayed to the user to aid in programming the IPG  14 . In the case, where a three-dimensional target tissue region is generated and displayed, the line  518  is revolved around the vertical axis of the electrodes to define a three-dimensional volume. 
     In alternative embodiments, the connecting points  520  may be located at other locations in the bar map  508 , such as, e.g., at the incremental intensity levels corresponding to the highest score vertical bars  510 , at a point halfway between the incremental intensity level corresponding to the highest score vertical bar  510  and the incremental intensity level at which an intolerable side-effect is perceived for the respective electrode. In the same manner as discussed above with respect to  FIGS. 13 and 14 , a range of differently aggressive target tissue regions  524  may be created with the different lines  518 . 
     Referring to  FIG. 19 . a clinical effect analysis screen  600  is similar to the clinical effect analysis screen  300  described above, with the exception that the CP  18  generates a volume map  608  instead of a bar map  308 . The clinical effect analysis screen  600  also includes a plurality of therapeutic effect trigger buttons (in this case, two therapeutic trigger buttons  606   a ,  606   b ) that can be actuated when the patient respectively experiences a plurality of different therapeutic effects, and a plurality of side-effect trigger buttons (in this case, two side-effect trigger buttons  606   c ,  606   d ) that can be actuated when the patient respectively experiences a plurality of different side-effects. For example, If the patient experiences one therapeutic effect, the user may actuate the first therapeutic trigger button  606   a , and if the patient experiences another different therapeutic effect, the user may actuate the other therapeutic trigger button  606   b . Likewise, if the patient experiences one side-effect, the user may actuate the first side-effect trigger button  606   c , and if the patient experiences another different side-effect, the user may actuate the other side-effect trigger button  606   d.    
     The different therapeutic effects (and likewise, the different side-effects) can be concurrently experienced by the patient or may be experienced by the patient during different times. In the same manner discussed above with respect to the clinical effect analysis screen  300 . the CP  18  quantifies the influence of each electrode  26  on the therapeutic effect by determining the range of incremental intensity levels at which a metric of each of the therapeutic effects occurs based on verbal feedback from the patient, and further determining the incremental intensity level at which a metric of each of the side-effects initially occurs. However, the CP  18  further quantifies the influence of each electrode  26  on the clinical effects by determining the electrodes that most influence the therapeutic effects and the side-effects. and generates the volume map  608  based on this determined clinical information. 
     The volume map  608  includes one or more target tissue regions (in this case, two target regions T 1 , T 2 ) displayed adjacent the electrodes that are determined to most influence the therapeutic effects, and one or more non-target tissue regions (in this case, two non-target tissue regions N 1 , N 2 ) displaced adjacent the electrodes that are determined to most influence the side-effects. In the illustrated embodiment, the regions are illustrates as being two-dimensional, although in other embodiments, the regions can be illustrated as being three-dimensional in nature. The portion of the map  608  that is hatched represents unexplored area, thereby allowing the user to readily determine the portion of the tissue has been explored and the portion of the tissue that has been explored (i.e., either designated as target tissue or non-target tissue). The different target regions T 1 , T 2  and non-target tissue regions N 1 , N 2  may be coded with different colors to enable the user to more easily distinguish the different target regions from each other and the target regions from the non-target regions. For example, the border of the first target tissue region T 1  may be colored green, the border of the second target tissue region T 2  maybe colored purple, and the borders of the non target tissue regions N 1 , N 2  may be colored orange. The target tissue regions T 1 , T 2  and non-target tissue regions N 1 , N 2  may also be filled in with different colors. 
     In one embodiment, the CP  18  estimates the size and shape of the target tissue region based on the highest incremental intensity level of therapeutic effects for each electrode. The CP  18  estimates the size and shape of the non-target tissue regions as being closely surrounding the electrode determined to influence the side-effects corresponding to the non-target tissue regions. Notably, the exact boundaries of the volume or region of tissue influenced by the electrodes may not be initially known (only that the volume or region of tissue is close by). However, the boundaries of the volume or region of tissue influenced by the electrodes may be estimated using an atlas of known target and non-target tissue regions or may be deduced as clinical information is collected by the CP  18  in subsequent stimulation scenario steps. In another embodiment, the CP  18  estimates either an electric field or a region of tissue activation at the highest incremental intensity level at which the therapeutic effects occur for each electrode, and determines the size and shape of the target tissue regions based on this information. Logical operators may be used to estimate each influencing electrode&#39;s contribution on the relevant target tissue region. 
     For example, when electrode E 1  is activated at an amplitude high enough to evoke a side-effect, the stimulated region could be modeled and one could deduce that somewhere on the outer boundary of the stimulation field model the excitation has resulted in a side-effect, but not know exactly which part of the stimulation field model boundary is responsible. If electrode E 2  is then activated, it may be that at some amplitude where a side effect is not yet reached, a new stimulation field model could be generated that overlaps the stimulation field model generated during the test with electrode E 1  (which evoked the side effect). It can now be deduced that the part of the boundary of the stimulation field model from the test of electrode E 1  (at side effect threshold) that is overlapping with the stimulation field model with the test of electrode E 2  (no side effect) is not responsible for the side effect, and this information can be graphically provided to the user (e.g.. change in color, etc. of some part of the clinical effects map). Note that other logical deductions can be performed as more information is gathered, and these deductions can be graphically conveyed to the user. 
     For example, as shown in  FIG. 19  and with further reference to  FIG. 11 , a relatively small non-target tissue region N 1  surrounds electrode E 1 , indicating to the user that electrode E 1  influences a side-effect, which corresponds to electrode E 1  being partially contained in the first side-effect region SE 1 , A relatively large target tissue region T 1  surrounds electrodes E 2 -E 5 , indicating to the user that electrodes E 2 -E 5  influence a therapeutic effect, with the width of the target tissue region T 1  being greatest at electrode E 4  and tapering down at electrodes E 2 , E 3 , and E 5 , indicating that electrode E 4  highly influences the therapeutic effect. This corresponds with electrode E 2  being adjacent the first therapy region TH 1 , electrode E 3  being fully within the first therapy region TH 1 , electrode E 4  being in the center of the first therapy region TH 1 , and electrode E 5  being partially contained in the first therapy region TH 1 . A relatively small target tissue region T 2  surrounds electrodes E 4 -E 5 , indicating to the user that electrodes E 4  and E 5  influence another therapeutic effect, which corresponds to electrode E 4  being fully contained within the second therapy region TH 2  and electrode E 5  being partially contained in the second therapy region TH 2 . A long scalloped non-target region surrounds electrodes E 6 -E 8 , indicating to the user that electrodes E 6 -E 8  influence another side-effect region, which corresponds to electrodes E 6 -E 8  being contained within the second side-effect region SE 2 . 
     Referring to  FIGS. 20 a -20 d   , the CP  18  may generate and display the volume map  608  in a progressive manner as clinical information is entered by the user. For example, after clinical information *s entered for electrode E 1 . the CP  18  may generate and display the first non-target tissue region N 1  around electrode E 1  ( FIG. 20 a   ). After clinical information is entered for electrode E 2 , the CP  18  may generate and display the first target tissue region T 1  around electrode E 2  ( FIG. 20 b   ). As clinical information is gathered for electrodes E 3 -E 5 , the first target tissue region T 1  grows larger, and the second target tissue region T 2  is added ( FIG. 20 c   ). As clinical information is gathered for electrodes E 6 -E 8 , the second non-target tissue region N 2  is added around these electrodes ( FIG. 20 d   ). 
     In an optional embodiment, instead of having the user manually test each electrode for clinical effects in a methodical manner, the CP  18  may suggest electrodes or electrode combinations that can be subsequently tested by the user to obtain the best clinical information, For example, referring to  FIG. 30 , an optimization algorithm can be used to estimate the best electrode configuration that provides the best therapeutic stimulation. The user may enter the position of the neurostimulation lead or leads into the CP  18  (e.g., based on atlas, stereotactic coordinates, user estimate, etc.), and the clinical effects data collected during programming, and the CP  18  may output the optimal electrode configuration, and optionally , the optimum pulse amplitude, pulse width and pulse rate. The optimization algorithm may be an optimization cost function designed with the objective of providing the “best guess” optimal electrode configuration and/or other stimulation parameters. Alternatively, the cost function could be designed to reveal all or a specific part of the clinical effects “map” or explore part of the anatomy. This latter objective could have the purpose of obtaining information that will subsequently inform an estimate of optimal therapeutic stimulation (e.g., the explored data may contribute to refining the lead-to-therapeutic region relationship), 
     Referring back to  FIG. 9 , the CP  18  is capable of modifying the anatomical regions of interest (namely, the therapy tissue region  124  and the side-effect tissue region  126 ), as obtained from the atlas, to be more patient-specific and to correct any mis-registration between the anatomical regions of interest and the neurostimulation lead  12 . This is accomplished by conveying electrical stimulation into the tissue of the patient via selected electrodes, thereby creating one or more clinical effects, determining an influence of the specified electrodes on the clinical effects, and modifying the anatomical regions of Interest (e.g., by spatially translating the anatomical regions of interest relative to the graphical electrode representation  26 ′ or by changing the shape of the anatomical regions of interest) based on the determined influence of the specified electrodes on the clinical effects. 
     In one embodiment shown in  FIG. 21 , an atlas modification screen  700  includes the previously described intensity level adjustment control  302 , electrode selection control  304 , and clinical information entry buttons  306  that can be actuated in the same manner described above with respect to the clinical effect analysis screen  300  to adjust the intensity of the electrical stimulation energy and select the electrode via which the electrical stimulation energy will be conveyed, and to enter clinical information as a result of such conveyed electrical stimulation energy, and in particular, to indicate to the CP  18  the intensity level at which the patient experiences a therapeutic effect or side-effect. The atlas modification screen  700  also includes the graphical representation of the neurostimulation lead  12 ′ and the corresponding electrodes  26 ′, as well as the registered anatomical regions of interest, and in this example, the therapy tissue region  124  and side-effect tissue region  126 . Based on clinical information entered by the user in response to conveying electrical stimulation energy via selected ones of the electrodes, the CP  18  may heuristically determine the manner in which the anatomical regions of interest should be modified. 
     In one embodiment, the CP  18  may determine the proximity between a displayed anatomical region of Interest and a specified electrode in the graphical electrode representation  26 ′. The determined proximity may simply be a rough estimate, such as, e.g., a relatively large proximity or a relatively small proximity. For example, as shown in  FIG. 22 a   . the proximity between the displayed therapy tissue region  124  and electrode E 3  may be determined to be relatively large. In another example, as shown in  FIG. 22 b   . the proximity between the displayed therapy tissue region  124  and electrode E 3  may be determined to be relatively small. 
     The CP  18  may then imply an actual proximity between the displayed anatomical region of interest and the specified electrode based on the determined influence of the specified electrode on the clinical effects. For example, electrode E 3  can be selected for conveying the electrical stimulation energy via the electrode selection control  304 , and the intensity of the conveyed electrical stimulation energy can be incrementally increased via the intensity adjustment control  302  until a therapeutic effect is perceived by the patient. If the intensity level at which the therapeutic effect is initially perceived is relatively low, the CP  18  may determine the actual proximity between the therapy tissue region  124  and electrode E 3  to be relatively small, and if the intensity level at which the therapeutic effect is initially perceived is relatively high, the CP  18  may determine the actual proximity between the therapy tissue region  124  and electrode E 3  to be relatively large. 
     The CP  18  may then spatially translate the displayed anatomical region of interest relative to the specified electrode in the graphical electrode representation  26 ′ to better match the displayed proximity to the actual proximity. This can be accomplished by moving either the displayed anatomical region of interest within the screen  700  or moving the graphical electrode representation  26 ′ within the screen  700 , such that there is a relative displacement between the displayed anatomical region of interest and the graphical electrode representation  26 ′. 
     For example, in the case where the proximity between the displayed therapy tissue region  124  and electrode E 3  is relatively large, as shown in  FIG. 22 a   . the CP  18  may displace the displayed therapy tissue region  124  toward electrode E 3  (as shown in phantom) if the actual proximity between the therapy tissue region  124  and electrode E 3  is determined to be relatively small. This is because the initial perception of a therapeutic effect at a relatively low intensity level, which indicates that the actual proximity between the therapy tissue region  124  and electrode E 3  is relatively small, contradicts the displayed proximity between the therapy tissue region  124  and electrode E 3  as being relatively large, and therefore, the displayed therapy tissue region  124  should be moved toward electrode E 3  to better match the actual proximity between the therapy tissue region  124  and electrode E 3 . Assuming that the actual proximity between the therapy tissue region  124  and the side-effect tissue region  126  are the same, the displayed side-effect tissue region  126  may also be spatially translated away from electrode E 3  in the same distance in the same direction that the displayed therapy tissue region  124  is specialty translated away from electrode E 3  (as shown in phantom) in order to maintain the spatial relationship between the therapy tissue region  124  and the side-effect tissue region  126 . 
     As another example, in the case where the proximity between the displayed therapy tissue region  124  and electrode E 3  is relatively small, as shown in  FIG. 22 b   , the CP  18  may displace the displayed therapy tissue region  124  away from electrode E 3  (as shown in phantom) if the actual proximity between the therapy tissue region  124  and electrode E 3  is determined to be relatively large. This is because the initial perception of a therapeutic effect at a relatively high intensity level, which indicates that the actual proximity between the therapy tissue region  124  and electrode E 3 &#39;s relatively large, contradicts the displayed proximity between the therapy tissue region  124  and electrode E 3  as being relatively small, and therefore, the displayed therapy tissue region  124  should be moved away from electrode E 3  to better match the actual proximity between the therapy tissue region  124  and electrode E 3 . Assuming that the actual proximity between the therapy tissue region  124  and the side-effect tissue region  126  are the same, the displayed side-effect tissue region  126  may also be spatially translated away from electrode E 3  the same direction in the same direction that the displayed therapy tissue region  124  is spatially translated away from electrode E 3  (as shown in phantom) in order to maintain the spatial relationship between the therapy tissue region  124  and the side-effect tissue region  126 . 
     The CP  18  may displace the displayed side-effect tissue region  126  relative to electrode E 3  or any other specified electrode using the same technique described above to displace the therapeutic tissue region  126  relative to electrode E 3 . 
     In another embodiment, the CP  18  may determine a relative influence of a specified electrode on a therapeutic effect and a side-effect, and spatially translate or rotate the displayed anatomical region of interest relative to the specified electrode in the graphical electrode representation  26 ′ based on the determined relative influence of the specified electrode on the therapeutic effect and the side-effect. 
     As one example, in the case where the proximity between the displayed therapy tissue region  124  and electrode E 3  is relatively large, and the proximity between the displayed side-effect region  124  and electrode E 3  is relatively small, as shown in  FIG. 23 a   , electrode E 3  can be selected for conveying the electrical stimulation energy via the electrode selection control  304 , and the intensity of the conveyed electrical stimulation energy can be incrementally increased via the intensity adjustment control  302  until a clinical effect is perceived by the patient. If a therapeutic effect is entered by the user as the first clinical effect that is perceived by the patient, the CP  18  may spatially translate the displayed therapy tissue region  124  toward electrode E 3 , and spatially translate the displayed side-effect tissue region  126  away from electrode E 3  (as shown in phantom). That is, because the initial perception of a therapeutic effect contradicts the display of electrode E 3  closer to the side-effect tissue region  126  than the therapy tissue region  124 , it is determined that electrode E 3  is actually closer to the therapy tissue region  124  than the side-effect tissue region  126 , and therefore, the displayed therapy tissue region  124  should be moved toward electrode E 3 , and the displayed side-effect tissue region  126  should be moved away from electrode E 3 . 
     As one example, in the case where the proximity between the displayed therapy tissue region  124  and electrode E 3  is relatively small, and the proximity between the displayed side-effect region  124  and electrode E 3  is relatively large, as shown in  FIG. 23 b   . electrode E 3  can be selected for conveying the electrical stimulation energy via the electrode selection control  304 , and the intensity of the conveyed electrical stimulation energy can be incrementally increased via the intensity adjustment control  302  until a clinical effect is perceived by the patient. If a side-effect is entered by the user as the first clinical effect that is perceived by the patient, the CP  18  may spatially translate the displayed therapy tissue region  124  away from electrode E 3  and spatially translate the displayed side-effect tissue region  126  toward electrode E 3  (as shown in phantom). That is, because the initial perception of a side-effect contradicts the display of electrode E 3  closer to the therapy tissue region  124  than the side-effect tissue region  126 , it is determined that electrode E 3  is actually closer to the side-effect region  126  than the therapy tissue region  124 , and therefore, the displayed therapy tissue region  124  should be moved away from electrode E 3 , and the displayed side-effect tissue region  126  should be moved toward electrode E 3 . 
     In another embodiment, two different electrodes are selected via the electrode selection control  304 , The electrodes are selected, such that one of the electrodes is further away from the displayed anatomical region of interest than the other electrode in the graphical electrode representation  26 ′, For example, electrodes E 2  and E 4  can be selected, with electrode E 2  being further away than electrode E 4  from the displayed therapy tissue region  124 , as shown in  FIG. 24 . The intensity of the electrical stimulation conveyed via the two different electrodes is adjusted via the intensity level adjustment control  302 , such that the CP  18  may quantify an influence of each of electrodes E 2  and E 4  on a therapeutic effect. 
     For example, the intensity of the electrical stimulation energy conveyed via electrode E 2  can be incrementally increased via the intensity adjustment control  302  until a therapeutic effect is perceived by the patient, and then the intensity of the electrical stimulation energy conveyed via electrode E 4  can be incrementally increased via the intensity adjustment control  302  until a therapeutic effect is perceived by the patient. If the intensity level at which the therapeutic effect is initially perceived for electrode E 2  is lower than the intensity level at which the therapeutic effect is initially-perceived for electrode E 4  (i.e., electrode E 2  has a higher influence than electrode E 4  on the therapeutic effect), the CP  18  spatially translate the displayed therapeutic tissue region  124  away from electrode E 4  and towards electrodes E 2  in the graphical electrode representation  26 ′. That is, because the intensity levels at which the therapeutic effect for electrodes E 2  and o 4  contradict the display of electrode E 2  being further than electrode E 4  from the therapy tissue region  124 , it is determined that electrode E 2  is actually closer than electrode E 4  to the therapy tissue region  124 , and therefore, the displayed therapy tissue region  124  should be toward electrode E 2  and away from electrode E 4 . 
     In still another embodiment, the CP  18  may change the shape of, warp, or morph an anatomical region of interest based on the clinical information entered via the clinical effect analysis screens  300 , 400 ,  500 , or  600  discussed above. For example, electrical stimulation energy may be serially conveyed via different ones of the electrodes E 1 -E 8 , and for each electrode, the intensity level of the conveyed electrical stimulation energy may be incrementally increased. The CP  18  may quantify the therapeutic effect by determining the highest intensity level at which a metric of the therapeutic effect occurs prior to an initial occurrence of a metric of a side-effect, and change the shape of the therapy tissue region based on the determined highest intensity levels for the different electrodes. That is, the higher the intensity level, the larger the therapy region at the respective electrode should be, and the CP  18  will accordingly modify the shape of the displayed therapy tissue region  124 . 
     In one example, the additional clinical effects information could be used by an algorithm (or manually by the user) to refine an atlas and/or the atlas and lead relationship such that a new atlas-to-lead relationship is more consistent with the clinical effects information that has been gathered, based on knowledge or expectations about stimulation of certain anatomical regions resulting in certain known clinical or physiological effects. If algorithm based, the algorithm is likely to include stimulation field models and their overlap or proximity to certain anatomical structures. Note that to get robust congruence of clinical data and the atlas-to-lead relationship, the warping or the morphing of the atlas may require more than translations and rotations, but perhaps also stretching and affine transformations, spline-type transformations, non-uniform rational B-spline transformations, and alternatives or the like. 
     Although we need to include rotating, warping, morphing, or generally reshaping. One imagines an algorithm that takes into account the imaging data and the clinical effects data, to get an overall hast match 
     Referring to  FIG. 25 , the CP  18  is capable of allowing a user to more easily match an electric field corresponding to a set of stimulation parameters to a desired electric field via an electric field selection screen  800 , which allows the user to select for an electric field one of a plurality of different pre-defined shapes stored within memory  82 , and define a location of the electric field relative to the graphical electrode representation  26 . To this end, the programming screen  800  includes the intensity level adjustment control  302  that can be actuated in the same manner described above to adjust the intensity of the conveyed electrical stimulation energy. The programming screen  800  also includes a graphical representation of the neurostimulation lead  12 ′ and the corresponding electrodes  26 ′, as well as anatomical regions of interest, and in this example, two therapy tissue regions  124   a  and  124   b , set off from the graphical representation of the neurostimulation lead  12 s and corresponding electrodes  26 ′. 
     Significantly, the electric field selection screen  800  includes an electric field selection control  802  that allows the user to select pre-defined electric field shapes that can be located relative to the graphical electrode representation  26 ′. In particular, the electric field selection control  802  displays various graphical shapes  804   a - 804   c  that can be dragged and dropped onto the graphical electrode representation  26 ′. In the illustrated embodiment, the first graphical shape  804   a  is an upside down pear shape (which emulates a bipolar electric field with the cathode at the top), the second graphical shape  804   b  is a right-side up pear shape (which emulates a bipolar electric field with the cathode at the bottom), and the third graphical shape  804   a  is a sphere (which emulates a monopolar electric field). In alternative embodiment, other types of shapes, such as a triangle or oval, may be provided. 
     Preferably, the user compares the pre-defined graphical shapes  804  to the therapeutic tissue region  124 , and selects the graphical shape  804  that best matches the shape of the therapeutic region  124 . The user preferably locates the selected shape  804  to match the location of the therapeutic tissue region  124  relative to the graphical electrode representation  26 ′. in an optional embodiment, the CP  18  will automatically locate the user-selected graphical shape  804  to match the location of the therapeutic tissue region  124 . Notably, as shown in  FIG. 26 , multiple graphical shapes  804  can be selected, dragged, and dropped onto the graphical electrode representation  26 ′. The selected graphical shapes  804  may either be different from each other, as illustrated in  FIG. 26 , or may be identical to each other. In either case, the CP  18  will prevent the multiple graphical shapes  804  from intersecting each other if the user attempts to move one of the selected graphical shapes  804  into another selected graphical shape  804 . 
     The manner in which a graphical shape  804  is selected, dragged, and dropped will depend on the nature of the user interface. For example, if She display screen  76  is conventional, a virtual pointing device (e.g., cursor controlled by the mouse  72 , joy stick, trackball, etc.) can be used to select, drag, and drop the graphical shape  804  onto the graphical electrode representation  26 ′. If the display screen  76  is a digitizer screen, a physical pointing device (e.g., a stylus or finger) can be used to select, drag, and drop the graphical shape  804  onto the graphical electrode representation  26 ′. 
     In the preferred embodiment, the CP  18  determines the combination of electrodes that best emulates the selected shape and defined location of the electric field. In the illustrated embodiment, the electrode combination that is determined to best match the electric field is a fractionalized electrode combination. The CP  18  may dynamically determine the fractionalized electrode combination as the graphical shape  804  is moved relative to the graphical electrode representation  26 ′. For example, as the graphical shape  804   a  is moved along the length of the graphical electrode representation  26 ′ (as shown by arrows), as shown in  FIG. 27 , the CP  18  may compute the fractionalized electrode combination corresponding to each of the locations of the graphical shape  804   a  relative to the electrodes. In an optional embodiment, once the graphical shape  804  is dragged and dropped onto the graphical electrode representation  26 ′, one side of the graphical shape  804  may be moved (e.g., in the direction of the arrow) in order to expand or contract the graphical shape  804  in one direction, as shown in  FIG. 28 . Furthermore, the size of the selected graphical shape  804  may be changed (either making it larger or smaller) by actuating the intensity level adjustment control  302  (i.e.. increasing the intensity increases the size of the selected graphical shape  804 . and decreasing the intensity decreases the size of the selected graphical shape  804 ). 
     The CP  18  may alternatively automatically determine the combination of electrodes that best emulates the selected shape and defined location of the electric field using any one of a variety of known techniques. For example, the CP  18  may theoretically overlay a grid of spatial observation points over the electric field, with each point assuming an electric field magnitude value. It can be assumed that the magnitude at the center of the electric field is highest, which exponentially tapers off towards the edges of the electric field. 
     Linearly independent constituent sources are then selected at the locations of electrodes E 1 -E 8 . Preferably, the constituent current sources are linearly independents. In the illustrated embodiment, dipoles are selected as constituent sources, because they are simple, and lend themselves well to conservation of current (i.e., if all constituent sources have conserved current (net zero), then any linear combination of them will also have conserved current). For example, a first constituent current source can be defined at the locations of electrodes E 1  and E 2  as −100% and +100%, respectively; a second constituent current source can be defined at the locations of electrodes E 2  and E 3  as −100% and +100%, respectively; a third constituent current source can be defined at the locations of electrodes E 3  and E 4  as −100% and +100%, respectively; and so on 
     Once the constituent sources are selected, the CP  18  determines the relative strengths of the constituent current sources that, when combined, result in estimated electric field potential values at the spatial observation points that best matches the desired field potential values at the spatial observation points. In particular, the CP  18  models the constituent current sources (e.g., using analytical and/or numerical models) and estimates the field potential values per unit current (V/mA) generated by each of the constituent current sources at the spatial observation points, and generating an m×n transfer matrix from the estimated field potential values per unit current, with m equaling the number of spatial observation points and n equaling the number of constituent sources. The relative strengths of the constituent current sources are determined using an optimization function that includes the transfer matrix A and the desired field potential values. This technique is described in further detail in U.S. patent application Ser. No. 12/938,282, entitled “System and Method for Mapping Arbitrary Electric Fields to Pre-Existing Lead Electrodes.” which is expressly incorporated herein by reference. 
     The CP  18  may instruct the IPG  14  to convey electrical stimulation energy to the fractionalized electrode combination determined to emulate the electric field, thereby creating one or more clinical effects. If the user selects different ones of the graphical shapes  804  and/or different locations for a selected graphical shape  804 , the IPG  14  may instruct the IPG  14  to convey electrical stimulation energy for each of the fractionalized electrode combinations determined to emulate the different electrical fields corresponding to the different graphical shapes and/or different locations for the graphical shapes, thereby creating a clinical effect for each of the determined fractionalized electrode combinations The user may enter a score for each of the fractionalized electrode combinations, in which case, the CP  18  may subsequently present the top-rated fractionalized electrode combinations to the user for therapy. 
     In another embodiment, the CP  18  may generate a plurality of different electric fields that best match a target tissue region (which may correspond to the target tissue region  324  generated in response to clinical information entered by the user or may be imported into the CP  18 ). The CP  18  can also determine the fractionalized electrode combinations that best emulate the different electric fields, e.g., in the manner described above. The CP  18  may present the best matching electric fields to the user (e.g., the top three matching electric fields), as shown in a program selection screen  900  shown in  FIG. 29 . 
     In particular, the program selection screen  900  may display three graphical shapes  902  corresponding to the shape of the there best matching electric fields, and a percentage coverage  904  for each electric field (i.e., the percentage of the area of the corresponding target tissue region covered by the respective electric field). The program selection screen  900  further includes selection buttons  906  that can be clicked by the user to prompt the CP  18  to instruct the IPG  14  to convey electrical stimulation energy in accordance with the fractionalized electrode combination corresponding to the selected electric field. The user may be prompted to incrementally increase the intensity of the conveyed electrical stimulation energy (e.g., via an intensity level adjustment control) until the therapy is optimum, 
     There may be instances where side-effects and therapy overlap. Hence, it may be useful to convey a constant amount of electrical stimulation energy, while varying the pulse amplitude and pulse width (i.e., inversely varying the pulse amplitude and pulse width, such that if the pulse amplitude is increased, the pulse width is decreased, and if the pulse amplitude is decreased, the pulse width is increased). For example, if the conveyed electrical stimulation energy has a pulse width of 60 μs and a pulse amplitude of 2 mA, the pulse width can be slowly decreased to 30 μs while the pulse amplitude is increased to slowly increased to  4 mA (stopping at various points to evaluate the therapy/side-effects). Similarly, the pulse width can be slowly increased to 120 μs from 60 μs while the pulse amplitude is decreased from 4 mA to 1 mA. 
     Once optimum therapy is achieved, the user may enter a score  908  and save the fractionalized electrode combination along with the adjusted intensity as a program. In the illustrated embodiment, this score  908  is a wellness that takes into account both therapy and side-effects. The different programs can be designated as either very conservative (e.g., minimal or moderate therapy with very little or no side-effects) that can be used during a period of time when maximum therapy is not needed (e.g., during sleep); very aggressive (e.g.. maximum therapy with substantial side-effects) that can be used during a period of time when maximum therapy is desired (e.g., during performance of intricate physical tasks); or moderate (moderate therapy with little side-effects). The CP  18  may have a control for selecting the program based on how conservative or aggressive it is. 
     Although the foregoing techniques have been described as being implemented in the CP  18 , it should be noted that this technique may be alternatively or additionally implemented in the RC  16 . Although particular embodiments of the present inventions have been shown and described, it will be understood that it is not intended to limit the present inventions to the preferred embodiments, and it will be obvious to those skilled in the art that various changes and modifications may be made without departing from the spirit and scope of the present inventions. Thus, the present inventions are intended to cover alternatives, modifications, and equivalents, which may be included within the spirit and scope of the present, inventions as defined by the claims.