Patent Publication Number: US-7216000-B2

Title: Neurostimulation therapy manipulation

Description:
This application claims priority from U.S. Provisional Application Ser. No. 60/422,260, filed Oct. 31, 2002, and U.S. Provisional Application Ser. No. 60/503,214, filed Sep. 15, 2003. The entire content of both Provisional Applications is incorporated herein by reference. 

   TECHNICAL FIELD 
   The invention relates to neurostimulation therapy and, more particularly, to manipulation of neurostimulation parameters. 
   BACKGROUND 
   An implantable medical device may be used to generate electrical stimulation, and deliver the stimulation to the nervous system of a patient, i.e., to, deliver neurostimulation therapy to the patient. Implantable medical devices are used to deliver neurostimulation therapy to patients to treat a variety of symptoms or conditions such as chronic pain, tremor, Parkinson&#39;s disease, epilepsy, incontinence, or gastroparesis. Typically, implantable medical devices deliver neurostimulation therapy in the form of electrical pulses via leads that include electrodes. To treat the above-identified symptoms or conditions, for example, the electrodes may be located proximate to the spinal cord, pelvic nerves, or stomach, or within the brain of a patient. 
   A clinician may select values for a number of programmable parameters in order to define the neurostimulation therapy to be delivered to a patient. For example, the clinician may select an amplitude, which may be a current or voltage amplitude, and pulse width for a stimulation waveform to be delivered to the patient, as well as a rate at which the pulses are to be delivered to the patient. The clinician may also select as parameters particular electrodes within an electrode set to be used to deliver the pulses, e.g., a combination of electrodes from the electrode set. 
   One existing programming technique used for programming spinal cord stimulation (SCS) therapy involves fixing pulse rate and width, testing a long list of electrode combinations, and asking the patient to optimize the amplitude for each. One or more electrode combinations are selected from the list, and the other parameters, e.g., pulse width and rate, are manipulated for each electrode combination to arrive at final parameter values for one or more programs. While this programming technique may involve manipulation by the patient under computer control, most neurostimulation therapy programming involves a clinician&#39;s laborious direct manipulation of parameter values. 
   Neurostimulation has been increasingly successful in clinical practice due to technical improvements, such as the development of leads with multiple electrode contacts, and implantable medical devices that support delivery of neurostimulation via the resulting larger electrode sets. However, complex systems with large electrode sets require increasing amounts of clinician and patient time to determine the most effective electrode combinations and stimulation parameters, i.e., program the implantable medical device to deliver neurostimulation therapy, for each patient. Further, specialized technical training may be required to effectively program such implantable medical devices, which may place even more time demands on the clinician. In other words, the potential advantages of these devices are compromised by the demands they place on valuable clinician and patient time. 
   SUMMARY 
   In general, the invention is directed toward manipulation of neurostimulation therapy parameter values. An electrical stimulation device delivers neurostimulation therapy to a patient based on values of electrical stimulation parameters. Where spinal cord stimulation (SCS) therapy is delivered, for example, the stimulation parameters may determine a location and strength of paresthesia experienced by the patient. 
   A user manipulates a stimulation parameter by manipulating a control device that generates a directional output based on the manipulation. A mapping system applies a calibrated map to select a value of the stimulation parameter based on the directional output of the control device. In some embodiments, the parameter values are electrode combinations, and the mapping system provides intuitive selection of electrode combinations. In particular, the mapping system may select electrode combinations such that a direction of manipulation of a directional controller of the control device corresponds to a direction of movement of paresthesia experienced by the patient. The mapping system may be calibrated based on patient paresthesia information received from a user. 
   In one embodiment, the invention is directed to a method comprising calibrating a map that maps an output of a control device to values of at least one electrical stimulation parameter of a stimulation device, receiving an output from the control device that reflects manipulation of a directional controller of the control device by a user, selecting a value for the electrical stimulation parameter based on the received output and the calibrated map, and providing the selected value to the stimulation device for application of electrical stimulation to a patient according to the selected value. 
   In another embodiment, the invention is directed to a system comprising an input circuit to receive an output from a control device, the output reflecting manipulation of a directional controller of the control device by a user, a memory to store a map that maps the output of the control device to values of at least one electrical stimulation parameter of a stimulation device, and a telemetry circuit. The system further comprises a processor to calibrate the map, select a value of the parameter based on the output of the control device and the calibrated map, and provide the selected value to a stimulation device via the telemetry circuit for application of electrical stimulation to a patient according to the selected value. 
   In a further embodiment, the invention is directed to a computer-readable medium containing instructions. The instructions cause a programmable processor to calibrate a map that maps an output of a control device to values of at least one electrical stimulation parameter of a stimulation device, receive an output from the control device that reflects manipulation of a directional controller of the control device by a user, select a value for the electrical stimulation parameter based on received output and the calibrated map, and provide the selected value to the stimulation device for application of electrical stimulation to a patient according to the selected value. 
   The invention may provide a number of advantages. For example, where the stimulation parameter manipulated is the combination of electrodes used to deliver the stimulation, the intuitive control device allows a user, such as a patient or clinician, to understand the relationship between a direction of manipulation and a direction of paresthesia movement. By providing intuitive control over a stimulation parameter, a mapping system according to the invention may allow the patient to control the stimulation parameter selection process without the assistance of a clinician. Further, the directional output of the control device provides a guided search, which allows the user, either the patient or the clinician, to select the stimulation parameter faster than a conventional trial-and-error search of all possible parameter configurations. 
   Additionally, the map is calibrated for each patient based on individual paresthesia information. Calibrating the map allows the control device to be mapped precisely to unique electrode positions and orientations, and unique anatomies and physiologies presented by different patients. The calibration technique also allows an amplitude scale factor to be built into the directional output of the control device. Therefore, when the user manipulates the control device to move the region of paresthesia, the amplitude will automatically scale to avoid an unexpected increase in amplitude of the electrical stimulation. 
   The details of one or more embodiments of the invention are set forth in the accompanying drawings and the description below. Other features, objects, and advantages of the invention will be apparent from the description and drawings, and from the claims. 

   
     BRIEF DESCRIPTION OF DRAWINGS 
       FIG. 1  is a block diagram illustrating an example electrical stimulation system that includes a control device and a mapping system according to the invention. 
       FIG. 2  is a schematic diagram illustrating the example electrical stimulation system of  FIG. 1  in greater detail. 
       FIG. 3  is a block diagram illustrating an example configuration of an implantable medical device of the electrical stimulation system of  FIGS. 1 and 2 . 
       FIG. 4  is a block diagram illustrating an example configuration of the mapping system of the electrical stimulation system of  FIGS. 1 and 2 . 
       FIG. 5  is a diagram illustrating an exemplary fixed map that may be calibrated and used by the mapping system of  FIGS. 1 ,  2  and  4  to map an output of the control device to a value of an electrical stimulation parameter. 
       FIG. 6  is a flow chart illustrating an example method that may be employed by a mapping system to map an output of a control device to a value of an electrical stimulation m parameter. 
       FIG. 7  is a flow chart illustrating an example fixed map calibration method that may be employed by a mapping system. 
       FIG. 8  is a flow chart illustrating an example electrode combination and neurostimulation program selection method that may be employed by a mapping system. 
       FIG. 9  is a schematic diagram illustrating another example embodiment of a control device. 
   

   DETAILED DESCRIPTION 
     FIG. 1  is a block diagram illustrating an electrical stimulation system  10 . Electrical stimulation system  10  includes a control device  12 , a mapping system  14 , and an electrical stimulation device, which in this case takes the form of an implantable medical device (IMD)  16 . IMD  16  is used to deliver neurostimulation therapy to a patient (not shown in  FIG. 1 ). IMD  16  may deliver neurostimulation in the form of electrical pulses to treat a symptom or condition of the patient, such as chronic pain, tremor, Parkinson&#39;s disease, epilepsy, incontinence, or gastroparesis. 
   Mapping system  14  and control device  12  may operate with, or be part of, a programming device or system used by a clinician (not shown), and in some cases the patient, to program delivery of neurostimulation by IMD  16 . In some embodiments, control device  12  and mapping system  14  are embodied in separate physical devices, and communicate via any of a variety of known wired or wireless connections. In some embodiments, mapping system is embodied within a computing device, and may be embodied as software executed by a processor of the computing device. The computing device may be the programming device used by the clinician, and in some cases the patient, to program IMD  16 . In some embodiments, a single device, such as the programming device, includes both control device  12  and mapping system  14 . 
   Control device  12  allows a user to manipulate one or more electrical stimulation parameters of IMD  16 . Exemplary electrical stimulation parameters include electrode combination, pulse rate, pulse width and current or voltage pulse amplitude. As will be described in greater detail below, control device  12  includes a directional controller such as a knob, a wheel, a joystick, a mouse, arrow keys on a keyboard, or the like, and generates a directional output that indicates a direction of manipulation of the directional controller by a user, such as the clinician or the patient. 
   Mapping system  14  uses a calibrated map to map the directional output of control device  12  to values of one or more of the stimulation parameters of IMD  16 . Mapping system  14  selects values of the stimulation parameter based on the directional output, and provides the selected values to IMD  16 . IMD  16  generates and delivers electrical stimulation according to the selected parameter values. 
   In exemplary embodiments, such as where IMD  16  is used to deliver spinal cord stimulation (SCS) therapy, the values of the stimulation parameter are combinations of electrodes, and a direction of movement of a paresthesia region is based on the direction of manipulation of the directional controller of control device  12  by the user. For example, as the user manipulates the directional controller in an upward direction, the paresthesia experienced by the patient moves up the patient&#39;s body. Mapping system  14  may take input from control device  12  either directionally, allowing the user to manipulate step-by-step or smoothly in an indicated direction, or spatially, allowing the user to indicate by location where in the overall range of adjustment the stimulation is desired. 
   Mapping system  14  and control device  12  may be used to program a plurality of IMDs  16  for a plurality of patients, and mapping system  14  may calibrate a map for each patient to correctly map the directional output of control device  12  to the arrangement of electrodes implanted within the patient. As will be described in greater detail below, mapping system  14  may initially select a fixed map based on information that describes the configuration of an electrode set implanted within the a patient, which may be input to mapping system  14  by the user. Mapping system  14  may then adapt the fixed map based on paresthesia information input to mapping system  14  by the user. Mapping system  14  may be calibrated either before or during use of electrical stimulation system  10 , or both. 
   Before use, mapping system  14  may be calibrated by the user manipulating control device  12  to several predetermined locations on the fixed map, i.e., predetermined locations within a manipulation range of the directional controller, and inputting paresthesia information at each location. The predetermined locations may comprise two corners of the fixed map, or four corners and a center point. The resulting map may be a liner or non-linear adaptation. The user may enter the paresthesia information by indicating regions of paresthesia on a body template. During use, mapping system  14  may continually calibrate a map by factoring received paresthesia and location information into the map. However, the invention is not limited to embodiments where map is calibrated during programming, or even to embodiments where paresthesia information is received from a user during programming. Mapping system  14  may apply Euclidian transforms for linear adaptation of a fixed map, or non-Euclidian transforms to accommodate for non-linearity and twists in the configuration of the electrode set implanted within the patient. 
   At each calibration location the user may input a minimum perception amplitude level of the stimulation pulse as paresthesia information, which may be used by mapping system  14  to adapt a fixed map as described above. The identified amplitude level may also allow mapping system  14  to create an amplitude scale factor to apply to electrode combinations within the map. In embodiments where the map includes amplitude scale factors for electrode combinations, the patient may then avoid an unexpected increase in amplitude of the electrical pulse generated by IMD  16  during paresthesia manipulation. The user may further adjust the amplitude to a comfortable level at any manipulation location. 
   Control device  12  and mapping system  14  may increase user efficiency when searching for stimulation parameters that produce effective paresthesia, e.g., programming IMD  16 , which may reduce the amount of clinician and patient time required for a programming session. In particular, mapping system  14  may provide an intuitive relationship between manipulation of a directional controller of control device  12  and values of a stimulation parameter. In exemplary embodiments where IMD  16  delivers SCS therapy, the user manipulates the directional controller in a direction, and mapping system selects an electrode combination such that a region of paresthesia experienced by the patient also moves in the direction. Consequently, the user may be able to intuitively move the region of paresthesia to the location of the patient&#39;s pain, and, therefore, more quickly select an appropriate electrode combination for inclusion in a program. 
   The invention is not, however, limited to use of control device  12  and mapping system  14  during a programming session. In some embodiments, control device  12  and mapping system  14  may be included in a programming device used by the patient for long-term adjustment and control of delivered neurostimulation, e.g., a patient programming device. In such embodiments, the patient may manipulate control device  12  to alter the electrical stimulation provided during different times of the day or when the patient is in different positions. 
     FIG. 2  is a schematic diagram illustrating the example electrical stimulation system of  FIG. 1  in greater detail. Electrical stimulation system  10  operates as described in reference to  FIG. 1 , and again includes a control device  12 , a mapping system  14 , and an IMD  16 . In the illustrated embodiment IMD  16  is coupled to leads  36 A and  36 B (collectively “leads  36 ”) that extend to positions proximate to a spinal cord  38  of a patient  34 . Leads  36  include electrodes (not shown in  FIG. 2 ), and IMD  16  may deliver SCS therapy in the form of electrical stimulation pulses via the electrodes. 
   As shown in  FIG. 2 , a directional controller  20 , a mode operation switch  24 , and an amplitude adjustment knob  26  are disposed within and/or on a housing  28  of control device  12 . In the illustrated embodiment, directional controller  20  is a joystick, and indicator button  22  is disposed on directional controller  20 . In other embodiments, any or all of directional controller  20 , indicator button  22 , mode operation switch  24 , and amplitude adjustment knob  26  may be software screen objects on a display. For example, in some embodiments, directional controller  20  may take the form of a representation of a joystick on a touch-screen display that is capable of being manipulated by a user. Further, operation mode switch  26  may be a rocker, a lever, a button, a key on a keyboard, a mouse, or the like. 
   Control device  12  generates an output as a function of the direction of manipulation of directional controller  20 . As described above, mapping system  14  uses a calibrated map to select a value for a stimulation parameter based on the output of control device  12 . In some embodiments, mapping device  14  is capable of using multiple calibrated maps, each map corresponding to a different stimulation parameter. In such embodiments, mapping system  14  may select one of the maps based on an operation mode designated by operation mode switch  24 , e.g., the position of switch  24 . 
   Where, as shown in  FIG. 2 , switch  24  is disposed on control device  12 , control device  12  sends a signal to mapping system  14  indicating the mode. Mapping system  14  selects one of the maps based on the signal. In other embodiments, operational mode switch  24  may be located on, and a component of, mapping system  14 . 
   In the illustrated embodiment, the operation modes available for selection by a user via switch  24  include a stimulation mode and a pulse mode. When the user selects stimulation mode, mapping system  14  selects a calibrated map that maps the output of control device  12  to combinations of the electrodes located on leads  36 . In other words, when mapping system  14  is operating in the stimulation mode, a user may use directional controller  20  to select electrode combinations. When the user selects pulse mode, mapping system selects a map that maps the output of control device  12  to one or more of stimulation pulse amplitude, width and rate, and the user may use directional controller  20  to adjust pulse amplitude, width and/or rate. 
   An exemplary technique that may be employed by a user, e.g., the clinician and/or patient  34 , to select stimulation parameters for inclusion in one or more programs using control device  12  and mapping system  14  involves use of mode switch  24 . The user selects stimulation mode using switch  24 , holding the width and rate of the pulses generated by IMD  16  constant while manipulating directional controller  20  to search for an electrode combination that provides effective stimulation to patient  34 . When an effective electrode combination is identified, the user may switch operation mode switch  24  to the pulse mode and manipulate the amplitude, width and/or rate of the generated stimulation pulse to see if the effectiveness of a program including the identified electrode combination can be improved. 
   In the case of the stimulation mode, the direction of manipulation of directional controller  20  corresponds to the direction of movement of a paresthesia region within patient  34 . In the case of the pulse mode, the direction of vertical manipulation of directional controller  20  corresponds to either increasing or decreasing the pulse amplitude, width and/or rate. The user may also manipulate pulse amplitude using amplitude adjustment knob  26 . 
   The effective electrode combination may be stored by mapping system  14  to be recalled later for application to IMD  16 , e.g., for further refinement of a program including the electrode combination. A user may cause mapping system  14  to store a plurality of parameters by pressing indicator button  22  when directional controller  20  is in a position that provides adequate paresthesia 
   In the embodiment illustrated in  FIG. 2 , control device  12  communicates wirelessly with mapping system  14 . Control device  12  and mapping system  14  may, for example, communicate via a radio frequency or infrared media, as is known in the art. Mapping system  14 , in this case, takes the form of a computing device that is coupled to an RF programming head  32 . Mapping system uses RF programming head  32  to transmit the electrical stimulation parameter values selected based on the output of control device  12  to IMD  16  via device telemetry as is known in the art. IMD  16  receives the stimulation parameters and generates a stimulation pulse based on the values. 
     FIG. 3  is a block diagram illustrating an example configuration of IMD  16 . IMD  16  may deliver neurostimulation therapy via electrodes  44 A–D of lead  36 A and electrodes  44 E–H of lead  36 B (collectively “electrodes  44 ”). Electrodes  44  may be ring electrodes. The configuration, type, and number of electrodes  44  illustrated in  FIG. 3  are merely exemplary. 
   IMD  16  includes a therapy delivery circuit  46 , a processor  48 , a telemetry circuit  50 , a memory  52 , and a program  54  stored in memory  52 . Electrodes  44  are electrically coupled to therapy delivery circuit  46  via leads  36 . Therapy delivery circuit  46  may, for example, include an output pulse generator coupled to a power source such as a battery. Therapy delivery circuit  46  may deliver electrical pulses to patient  34  via at least some of electrodes  44  under the control of a processor  48 . 
   Processor  48  controls therapy delivery circuit  46  to deliver stimulation according to program  54 . Specifically, processor  48  may control circuit  46  to deliver electrical stimulation pulses with an amplitude, width, and rate specified by program  54 . Processor  48  may also control circuit  46  to deliver the pulses via a selected subset of electrodes  44  with selected polarities, as specified by program  54 . Processor  48  may include a microprocessor, a controller, a digital signal processor (DSP), an application specific integrated circuit (ASIC), a field-programmable gate array (FPGA), discrete logic circuitry, or the like. 
   Telemetry circuit  50  allows processor  48  to communicate with mapping system  14 . During the programming process described above, processor  48  receives values of one or more stimulation parameters selected by mapping system  14  based on the output of control device  12  via telemetry circuit  50 , and stores with values within memory  52  as part of program  54 . Processor  48  may update program  54 , and direct therapy delivery circuit  46  to deliver stimulation pulse according to new values for a stimulation parameter as new values for a parameter are received from mapping system. 
   In addition to program  54 , memory  52  may include program instructions that, when executed by processor  48 , cause IMD  16  to perform the functions ascribed to IMD  16  herein. Memory  52  may include any volatile, non-volatile, magnetic, optical, or electrical media, such as a random access memory (RAM), read-only memory (ROM), non-volatile RAM (NVRAM), electrically-erasable programmable ROM (EEPROM), flash memory, and the like. 
     FIG. 4  is a block diagram illustrating an example configuration of mapping system  14 . Mapping system  14  includes a memory  60  that stores fixed maps  62  and a calibrated map  64 , a processor  66 , an input/output (I/O) circuit  68 , and a telemetry circuit  70 . As described above, mapping system  14  may operate with, be part of, or may be a programming device or system used by a clinician (not shown), and in some cases patient  34 , to program delivery of neurostimulation by IMD  16 . 
   Processor  66  receives an output form control device  12  via I/O circuit  68 . Processor  66  uses calibrated map  64  to select values of a stimulation parameter based on the output of control device  12 , and transmits selected parameter values to IMD  16  via telemetry circuit  70  for application of neurostimulation according to the parameter value to patient  34 . Mapping system  14  may include RF programming head  32  ( FIG. 2 ) coupled to telemetry circuit  70  to transmit the stimulation parameter to IMD  16 . 
   In exemplary embodiments, processor  66  receives electrode arrangement, type, and number information from a user via I/O circuit  68 . Additional information received via I/O circuit  68  may include pulse width and rate values, amplitude levels, and pain and paresthesia region indications made by a user on a body diagram. The dynamic body diagram may comprise an outline template of a body displayed on a display (not shown) coupled to mapping system  14 . The region indications may be made by the user with a mouse, or the display may be a touch screen and the user may use a stylus to indicate regions on the body diagram. In some embodiments, the display and/or a pointing device may be part of control device  12 , which provides the information to processor  66  via I/O circuit  68 . 
   Processor  66  determines which of fixed maps  62  stored in memory  60  best matches the received electrode information, and calibrates the selected fixed map  62  to generate calibrated map  64 . The selected fixed map  62  may be calibrated by the user manipulating directional controller to locations within the selected fixed map  62 , e.g., locations within the manipulation range of directional controller  20 , and entering paresthesia information including the body diagram indications and a minimum amplitude level at which paresthesia is perceived by patient  34 . Processor  66  uses the received location and paresthesia information to adapt the selected fixed map  62 , i.e., generate calibrated map  64  for patient  34 . 
   By generating calibrated maps  64 , mapping system  14  may account for patient-to-patient differences in electrode position and orientation, and nervous system anatomy and physiology. In particular, where IMD  16  is used to deliver SCS therapy and calibrated map  64  maps a directional output of control device  12  to electrode combinations, generation of calibrated map  64  by mapping system  14  may enable a direction of manipulation of directional controller  20  to correspond to a direction of movement of paresthesia experienced by patient  34 . In some embodiments, map  64  may be further calibrated by paresthesia information received while mapping system  14  is being used by a user, such as a clinician or patient, to test stimulation parameters for inclusion in a program. 
   Processor  66  may include a microprocessor, a controller, a DSP, an ASIC, an FPGA, discrete logic circuitry, or the like. In addition to maps  62 ,  64 , memory  60  may store program instructions that, when executed by processor  66 , cause mapping system  14  to perform the functions ascribed to mapping system  14  herein. Memory  60  may include any volatile, non-volatile, fixed, removable, magnetic, optical, or electrical media, such as a RAM, ROM, CD-ROM, hard disk, removable magnetic disk, memory cards or sticks, NVRAM, EEPROM, flash memory, and the like. 
     FIG. 5  is a diagram illustrating an exemplary fixed map  74  that may be calibrated and used by mapping system  14  to map an output of control device  12  to one of electrode combinations  72 A–I (hereinafter “electrode combinations  72 ”) Fixed map  74  may be one of fixed maps  62  available for selection by mapping system  14 . Fixed map  74  corresponds to an eight contact electrode set, with four contacts on each of two leads. Consequently, mapping system  14  may select fixed map  74  if information describing the configuration of electrodes  44  within patient  34  matches this description. Such a configuration is typically used for delivery of SCS therapy, with the electrodes may be placed essentially parallel to spinal cord  38  with four electrodes left and four electrodes right of the midline. 
   Electrode combinations  72  identify the polarity of each of the electrodes of an electrode set according to that combination. Electrode contacts that are off are represented with a “0”, and those that are on are represented with a “+” for an anode and a “−” for a cathode. The illustrated combinations  72  are combinations that would be selected by mapping device  14  during movement of directional controller  20  from a top left position to a bottom right position within its manipulation range. 
   Fixed map  74  may include other combinations  72  (not shown) that correspond to movement to other locations and in other directions within the manipulation range of directional controller  20 . Further, when calibrated by mapping system  14 , the combinations  72  associated with various positions within the manipulation range of directional controller  20  may be altered from those of fixed map  74  to create calibrated map  64 . Specifically, combinations  72  may be altered to account for patient-to-patient electrode configuration, anatomical and physiological differences, such that the position to which directional controller  20  is manipulated within its manipulation range corresponds to the direction of movement of paresthesia within patient  34 . 
     FIG. 6  is a flow chart illustrating an example method that may be employed by mapping system  14  to map an output of a control device to a value of an electrical stimulation parameter. Mapping system  14  receives electrode arrangement, type, and number information from a user regarding the set of electrodes  44  implanted within patient  34 . Processor  66  of mapping system  14  selects one of fixed maps  62  stored in memory  60  that closely matches the received electrode information. The selected fixed map is calibrated ( 80 ) based on location and paresthesia information received by mapping system  14  via I/O device  68 . In some embodiments, the location and paresthesia information is received via control device  12 . The calibration may include altering electrode combinations of the selected fixed map  62  to match the direction of movement of patient  34  to the direction of movement of a directional controller  20  of control device  12 . Processor  66  stores the calibrated map  64  in memory  60 . 
   Mapping system  14  receives directional output from user manipulation of control device  12  ( 82 ). In exemplary embodiments, the directional output reflects a direction of manipulation of a directional controller of control device  12 . Mapping system  14  applies calibrated map  64  to map the received directional output to a value of an electrical stimulation parameter of IMD  16  ( 84 ). Once the corresponding electrical stimulation parameter value is selected, processor  66  transmits the parameter value to IMD  16  ( 86 ) via telemetry circuit  70 . IMD  16  may then generate electrical stimulation pulses according to the received parameter value for delivery to patient  34 . 
     FIG. 7  is a flow chart illustrating an example fixed map calibration method that may be employed by mapping system  14 . Mapping system  14  receives electrode arrangement, type, and number information ( 90 ) from a user describing the configuration of electrodes  44  within patient  34 . Processor  66  of mapping system  14  selects one of fixed maps  62  stored in memory  60  that closely matches the received electrode information ( 92 ). Processor  66  receives a first directional output from user manipulation of directional controller  20  of control device  12  in a first direction via I/O circuit  68  ( 94 ). Processor  66  applies the selected fixed map  62  to select a first value for an electrical stimulation parameter, e.g., a first electrode combination, based on the first directional output ( 96 ). Once the corresponding first electrical stimulation parameter value is selected, processor  66  transmits the parameter value to IMD  16  via telemetry circuit  70 . IMD  16  may then generate and deliver stimulation pulses according to the selected parameter value to patient  34  ( 98 ). Processor  66  receives first patient paresthesia information from the user as a response to the applied stimulation pulse ( 100 ). In some embodiments, as described above, the paresthesia information may include information indicating a region of paresthesia on a body template image, and/or a pulse amplitude value associated with paresthesia perception. 
   Processor  66  then receives a second directional output from user manipulation of directional controller  20  in a second direction ( 102 ). Processor  66  applies the selected fixed map  62  to select a second value for the electrical stimulation parameter, e.g., a second electrode combination  72 , based on the second directional output ( 104 ). Once the corresponding second electrical stimulation parameter value is selected, processor  66  transmits the parameter value to IMD  16  via telemetry circuit  70 . IMD  16  may then generate and deliver electrical stimulation pulses according to the second parameter value to patient  34  ( 106 ). Processor  66  receives second patient paresthesia information from the user as a response to the applied stimulation pulse ( 108 ). 
   Processor  66  modifies the selected fixed map  62  based on the first and second paresthesia information ( 110 ) received by mapping system  14  from control device  12  via I/O circuit  68 . Processor  66  in mapping system  14  stores the modified fixed map as calibrated map  64  in memory  60 . In exemplary embodiments, the modification may include altering electrode combinations  72  of the selected fixed map  62  such that a direction of movement of paresthesia for patient  34  corresponds to the direction of the manipulation of directional controller  20 . 
   In some embodiments, the user manipulates directional controller  20  in a first and second direction by manipulating directional controller  20  to diametrically opposed corners of a manipulation range of directional controller  20 . In some embodiments, the user manipulates directional controller  20  in additional directions during calibration. For example, the user may in some embodiments manipulate directional controller  20  to four corners and a center point of a manipulation range of directional controller  20 . In such embodiments, processor  66  receives paresthesia information describing paresthesia experienced by patient  34  at each of these locations for generation of calibrated map  64  based on the paresthesia information. 
     FIG. 8  is a flow chart illustrating an example electrode combination and neurostimulation program selection method that may be employed by mapping system  14 . Mapping system  14  receives a directional output from control device based on user manipulation of directional controller  20 . In the case of multiple operation modes, the directional output is mapped to electrode combinations when control device  12  is in the stimulation mode. 
   The user manipulates directional controller  20  to test regions of paresthesia generated by different electrode combinations ( 120 ). Mapping system  14  receives a user indication from control device  12  when an electrode combination creates an effective paresthesia region ( 122 ) for patient  4 . For example, the user may identify effective combinations by pressing indicator button  22  when directional controller  20  is in a position that produces effective paresthesia. 
   The preferred combinations are stored in memory  60  of mapping system  14  for retesting by the user ( 124 ). During retesting, the user may further use control device  12  to improve the effects of the stored electrode combinations by, for example, moving mode switch  24  and using directional controller  20  to alter additional electrical stimulation parameters of a program associated with the electrode combination. For example, the user may manipulate directional controller up and down to increase and decrease stimulation parameters, such as pulse amplitude, width and rate. In some embodiments, control device  12  may include a dedicated amplitude knob  26  for adjustment of pulse amplitude. 
   Mapping system  14  receives an electrode combination selected by the user ( 126 ) during retesting. In some embodiments, processor  66  may further modify calibrated map  64  so that the selected combination corresponds to a center of a manipulation range of directional controller  20 . With calibrated map  64  so modified, a user may more easily test electrode combinations that are “adjacent” to the store electrode combinations. 
   Mapping system  14  may store additional information describing possible electrode combinations that are not represented within a calibrated map  64  within memory  60 . Based on the received electrode arrangement, type, and number information, processor  66  may, in some embodiments, identify electrode combinations not represented within calibrated map  64  that produce stimulation therapy substantially equivalent to the user selected combination ( 128 ). The user may test the equivalent combinations ( 130 ) by controlling mapping system  14  to provide the equivalent combination to IMD  16  to, for example, identify the combination that generates effective paresthesia while using the least amount of power or the fewest electrodes. Processor  66  receives an electrode combination selected by the user from the equivalent and or adjacent electrode combinations, along with additional parameters ( 132 ) such as an amplitude level, and pulse width and rate values, and transmits the parameters to IMD  16  via telemetry circuit  70 . IMD  16  stores the parameters as a program  54  ( 134 ) in memory  52  of IMD  16  that is the result of the programming process, which will thereafter be available for use by processor  48  to control delivery of neurostimulation therapy to patient  34  outside of the clinical setting. 
     FIG. 9  is a schematic diagram illustrating another example embodiment of a control device  140 . As shown in  FIG. 9 , control device  140  includes a directional controller  142 , an indicator button  144 , a mode operation switch  146 , an amplitude adjustment knob  148 , a housing  150 , which may be similar to directional controller  20 , indicator button  22 , mode operation switch  24 , amplitude adjustment knob  26 , and housing  28  of control device  12  described above with reference  FIG. 2 . Control device  140  additionally includes a display screen  152  with a dynamic body template  154  and body template control buttons  156  displayed on display screen  152 . As described above with reference to  FIG. 2 , any or all of directional controller  142 , indicator button  144 , mode operation switch  146 , and amplitude adjustment knob  148  may be software screen objects on display screen  152 . For example, in some embodiments, directional controller  142  may take the form of a representation of a joystick on a touch-screen display  152  that is capable of being manipulated by a user. 
   In exemplary embodiments, mapping system  14  may be implemented as software executed by a processor (not shown) of control device  140 . In other words, a mapping system  14  according to the invention may comprise a control device  12 ,  140 . Further, control device  140  that implements mapping system  14  may be a clinician programming device used to program for programming IMD  16 , and may provide additional functionality known in the art to be provided by such devices, such as collection of demographic or symptom information from patient  34 . A control device  140  that implements mapping system  14  may be coupled to RF programming head  32  to deliver electrical stimulation parameter values to IMD  16 . 
   A user may input pain and/or paresthesia region indications to mapping system  14  via dynamic body template  154 . Display screen  152  may be a touch screen to accept the body region indications via a stylus (not shown); otherwise a pointing device, such as a mouse may be coupled to control device  140  and used by the user to indicate the body regions on display screen  152 . Body template control buttons  156  allow the user to view additional dynamic body templates in order to specify pain and/or paresthesia experienced by patient  34  on his or her sides or back. 
   Display screen  152  may also display parameter values. For example, the selected electrode combinations may be illustrated on display screen  152  during testing. The pulse width and rate values for the applied stimulation pulse may be displayed, as well as the amplitude level. In this way, the user may relate the parameter values with the resulting paresthesia and further reduce the amount of time needed to select stimulation parameters. 
   Various embodiments of the invention have been described. However, one skilled in the art will appreciate that various modifications may be made to these embodiments without departing from the scope of the invention. For example, one embodiment described includes a method for adapting a fixed electrode combination map to a specific patient. The fixed map is chosen by a processor in a mapping system based on electrode configuration information received from a user. However, if the patient&#39;s electrode configuration is substantially identical to one of the fixed maps, then adapting the map may not be necessary. In that case, the fixed map may still be calibrated to generate an amplitude scale factor, but the calibration will not alter the electrode combination order of the fixed map. These and other embodiments are within the scope of the following claims.