Patent Publication Number: US-2022233862-A1

Title: Devices for controlling spinal cord modulation for inhibiting pain, and associated systems and methods, including controllers for automated parameter selection

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
     The present application claims priority to U.S. Provisional Application No. 61/619,358, filed Apr. 2, 2012 and incorporated herein by reference. To the extent the foregoing application and/or any other materials conflict with the present disclosure, the present disclosure controls. 
    
    
     TECHNICAL FIELD 
     The present disclosure is directed generally to devices for controlling spinal cord modulation for inhibiting pain, and associated systems and methods, including simplified controllers. 
     BACKGROUND 
     Neurological stimulators have been developed to treat pain, movement disorders, functional disorders, spasticity, cancer, cardiac disorders, and various other medical conditions. Implantable neurological stimulation systems generally have an implantable pulse generator and one or more leads that deliver electrical pulses to neurological tissue or muscle tissue. For example, several neurological stimulation systems for spinal cord stimulation (SCS) have cylindrical leads that include a lead body with a circular cross-sectional shape and one or more conductive rings spaced apart from each other at the distal end of the lead body. The conductive rings operate as individual electrodes and, in many cases, the SCS leads are implanted percutaneously through a large needle inserted into the epidural space, with or without the assistance of a stylet. 
     Once implanted, the pulse generator applies electrical pulses to the electrodes, which in turn modify the function of the patient&#39;s nervous system, such as by altering the patient&#39;s responsiveness to sensory stimuli and/or altering the patient&#39;s motor-circuit output. In pain treatment, the pulse generator applies electrical pulses to the electrodes, which in turn can generate sensations that mask or otherwise alter the patient&#39;s sensation of pain. For example, in many cases, patients report a tingling or paresthesia that is perceived as more pleasant and/or less uncomfortable than the underlying pain sensation. While this may be the case for many patients, many other patients may report less beneficial effects and/or results. Accordingly, there remains a need for improved techniques and systems for addressing patient pain. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1A  is a partially schematic illustration of an implantable spinal cord modulation system positioned at the spine to deliver therapeutic signals in accordance with several embodiments of the present disclosure. 
         FIG. 1B  is a partially schematic, cross-sectional illustration of a patient&#39;s spine, illustrating representative locations for implanted lead bodies in accordance with embodiments of the disclosure. 
         FIG. 2  is a bar chart illustrating pain reduction levels for patients over a four day period of a clinical study, during which the patients received therapy in accordance with an embodiment of the disclosure, as compared with baseline levels and levels achieved with conventional spinal cord stimulation devices. 
         FIG. 3  is a bar chart comparing the number of times patients receiving therapy in accordance with an embodiment of the present disclosure during a clinical study initiated modulation changes, as compared with similar data for patients receiving conventional spinal cord stimulation. 
         FIG. 4  is a bar chart illustrating activity performance improvements for patients receiving therapy in accordance with an embodiment of the disclosure, obtained during a clinical study. 
         FIG. 5A  is a bar chart comparing activity performance levels for patients performing a variety of activities, obtained during a clinical study. 
         FIGS. 5B and 5C  are bar charts illustrating sleep improvement for patients receiving therapy in accordance with embodiments of the disclosure, obtained during a clinical study. 
         FIG. 6A  is a bar chart illustrating successful therapy outcomes as a function of modulation location for patients receiving therapy in accordance with an embodiment of the disclosure, obtained during a clinical study. 
         FIGS. 6B and 6C  are flow diagrams illustrating methods conducted in accordance with embodiments of the disclosure. 
         FIG. 7A  illustrates an arrangement of leads used during a follow-on clinical study in accordance with an embodiment of the disclosure. 
         FIG. 7B  illustrates results obtained from a follow-on clinical study of patients receiving therapy in accordance with an embodiment of the disclosure. 
         FIG. 8  is a schematic illustration identifying possible mechanisms of action for therapies in accordance with the present disclosure, as compared with an expected mechanism of action for conventional spinal chord stimulation. 
         FIG. 9  is a partially schematic illustration of a lead body configured in accordance with an embodiment of the disclosure. 
         FIGS. 10A-10C  are partially schematic illustrations of extendible leads configured in accordance with several embodiments of the disclosure. 
         FIGS. 11A-11C  are partially schematic illustrations of multifilar leads configured in accordance with several embodiments of the disclosure. 
         FIGS. 12A-12B  illustrate patient-operated remote control devices in accordance with particular embodiments of the disclosure. 
         FIGS. 13A-13E  illustrate practitioner-operated devices in accordance with particular embodiments of the disclosure. 
         FIGS. 13F and 13G  illustrate representative display presentations in accordance with particular embodiments of the disclosure. 
         FIG. 13H  is a block diagram illustrating an automated process for selecting therapy parameters in accordance with particular embodiments of the disclosure. 
     
    
    
     DETAILED DESCRIPTION 
     1.0 Introduction 
     The present technology is directed generally to spinal cord modulation and associated systems and methods for inhibiting pain. In particular embodiments, waveforms in accordance with the present technology have high frequency elements or components (e.g., portions having high fundamental frequencies), and generally produce reduced or eliminated side effects. Such side effects can include unwanted motor stimulation or blocking, and/or interference with sensory functions other than the targeted pain. Several embodiments also provide simplified spinal cord modulation systems and components, and simplified procedures for the practitioner and/or the patient. Specific details of certain embodiments of the disclosure are described below with reference to methods for modulating one or more target neural populations (e.g., nerves) or sites of a patient, and associated implantable structures for providing the modulation. Although selected embodiments are described below with reference to modulating the dorsal column, dorsal horn, dorsal root, dorsal root entry zone, and/or other particular regions of the spinal column to control pain, the modulation may in some instances be directed to other neurological structures and/or target neural populations of the spinal cord and/or other neurological tissues. Some embodiments can have configurations, components or procedures different than those described in this section, and other embodiments may eliminate particular components or procedures. A person of ordinary skill in the relevant art, therefore, will understand that the disclosure may include other embodiments with additional elements, and/or may include other embodiments without several of the features shown and described below with reference to  FIGS. 1A-13H . 
     In general terms, aspects of many of the following embodiments are directed to producing a therapeutic effect that includes pain reduction in the patient. The therapeutic effect can be produced by inhibiting, suppressing, downregulating, blocking, preventing, or otherwise modulating the activity of the affected neural population. In many embodiments of the presently disclosed techniques, therapy-induced paresthesia is not a prerequisite to achieving pain reduction, unlike standard SCS techniques. It is expected that the techniques described below with reference to  FIGS. 1A-13H  can produce more effective, more robust, less complicated and/or otherwise more desirable results than can existing spinal cord stimulation therapies. 
     Many embodiments of the technology described below may take the form of computer-executable instructions, including routines executed by a programmable computer. Those skilled in the relevant art will appreciate that the technology can be practiced on computer systems other than those shown and described below. The technology can be embodied in a special-purpose computer or data processor that is specifically programmed, configured or constructed to perform one or more of the computer-executable instructions described below. Accordingly, the terms “computer” and “controller” as generally used herein refer to any data processor and can include Internet appliances and hand-held devices (including palm-top computers, wearable computers, cellular or mobile phones, multi-processor systems, processor-based or programmable consumer electronics, network computers, mini computers and the like). Information handled by these computers can be presented at any suitable display medium, including a CRT display or LCD. 
     The technology can also be practiced in distributed environments, where tasks or modules are performed by remote processing devices that are linked through a communications network. In a distributed computing environment, program modules or subroutines may be located in local and remote memory storage devices. Aspects of the technology described below may be stored or distributed on computer-readable media, including magnetic or optically readable or removable computer disks, as well as distributed electronically over networks. Data structures and transmissions of data particular to aspects of the technology are also encompassed within the scope of particular embodiments of the disclosed technology. 
       FIG. 1A  schematically illustrates a representative patient system  100  for providing relief from chronic pain and/or other conditions, arranged relative to the general anatomy of a patient&#39;s spinal cord  191 . The overall patient system  100  can include one or more signal delivery devices  110 , which may be implanted within a patient  190 , typically at or near the patient&#39;s spinal cord midline  189 , coupled to an implantable pulse generator  101 . The signal delivery devices  110  carry features for delivering therapy to the patient  190  after implantation. The pulse generator  101  can be connected directly to the signal delivery devices  110 , or it can be coupled to the signal delivery devices  110  via a signal link or lead extension  102 . In a further representative embodiment, the signal delivery devices  110  can include one or more elongated lead(s) or lead body or bodies  111  (identified individually as a first lead  111   a  and a second lead  111   b ). As used herein, the terms “lead” and “lead body” include any of a number of suitable substrates and/or support members that carry devices for providing therapy signals to the patient  190 . For example, the lead or leads  111  can include one or more electrodes or electrical contacts that direct electrical signals into the patient&#39;s tissue, such as to provide for patient pain relief. In other embodiments, the signal delivery devices  110  can include structures other than a lead body (e.g., a paddle) that also direct electrical signals and/or other types of signals to the patient  190 . 
     The pulse generator  101  can transmit therapy signals (e.g., electrical signals) to the signal delivery devices  110  that up-regulate (e.g., stimulate or excite) and/or down-regulate (e.g., block or suppress) target nerves. As used herein, and unless otherwise noted, to “modulate” or provide “modulation” to the target nerves refers generally to having either type of the foregoing effects on the target nerves. The pulse generator  101  can include a machine-readable (e.g., computer-readable) medium containing instructions for generating and transmitting suitable therapy signals. The pulse generator  101  and/or other elements of the system  100  can include one or more processor(s)  107 , memory unit(s)  108  and/or input/output device(s)  112 . Accordingly, the process of providing electrical signals, providing guidance information for positioning the signal delivery devices  110 , and/or executing other associated functions can be performed by computer-executable instructions contained by computer-readable media located at the pulse generator  101  and/or other system components. The pulse generator  101  can include multiple portions, elements, and/or subsystems (e.g., for directing signals in accordance with multiple signal delivery parameters), carried in a single housing, as shown in  FIG. 1A , or in multiple housings. 
     In some embodiments, the pulse generator  101  can obtain power to generate the therapy signals from an external power source  103 . The external power source  103  can transmit power to the implanted pulse generator  101  using electromagnetic induction (e.g., RF signals). For example, the external power source  103  can include an external coil  104  that communicates with a corresponding internal coil (not shown) within the implantable pulse generator  101 . The external power source  103  can be portable for ease of use. 
     During at least some procedures, an external stimulator or trial modulator  105  can be coupled to the signal delivery devices  110  during an initial procedure, prior to implanting the pulse generator  101 . For example, a practitioner (e.g., a physician and/or a company representative) can use the trial modulator  105  to vary therapy parameters provided to the signal delivery devices  110  in real time, and select optimal or particularly efficacious parameters. These parameters can include the location from which the electrical signals are emitted, as well as the characteristics of the electrical signals provided to the signal delivery devices  110 . In a typical process, the practitioner uses a cable assembly  120  to temporarily connect the trial modulator  105  to the signal delivery devices  110 . The practitioner can test the efficacy of the signal delivery devices  110  in an initial position. The practitioner can then disconnect the cable assembly  120  (e.g., at a connector  122 ), reposition the signal delivery devices  110 , and reapply the electrical signals. This process can be performed iteratively until the practitioner obtains the desired position for the signal delivery devices  110 . Optionally, the practitioner may move the partially implanted signal delivery devices  110  without disconnecting the cable assembly  120 . Furthermore, in some embodiments, the iterative process of repositioning the signal delivery devices  110  and/or varying the therapy parameters, may not be performed. 
     The pulse generator  101 , the lead extension  102 , the trial modulator  105  and/or the connector  122  can each include a receiving element  109 . Accordingly, the receiving elements  109  can be patient implantable elements, or the receiving elements  109  can be integral with an external patient treatment element, device or component (e.g., the trial modulator  105  and/or the connector  122 ). The receiving elements  109  can be configured to facilitate a simple coupling and decoupling procedure between the signal delivery devices  110 , the lead extension  102 , the pulse generator  101 , the trial modulator  105  and/or the connector  122 . Receiving elements  109  can be at least generally similar in structure and function to those described in U.S. patent application Ser. No. 13/291,985, entitled MEDICAL DEVICE CONTACT ASSEMBLIES FOR USE WITH IMPLANTABLE LEADS, AND ASSOCIATED SYSTEMS AND METHODS, filed Nov. 8, 2011, which is incorporated by reference herein in its entirety. 
     After a trial period with the trial modulator  105 , the practitioner can implant the implantable pulse generator  101  within the patient  190  for longer term treatment. The signal delivery parameters provided by the pulse generator  101  can still be updated after the pulse generator  101  is implanted, via a wireless physician&#39;s programmer  117  (e.g., a physician&#39;s laptop, physician&#39;s remote, etc.) and/or a wireless patient programmer  106  (e.g., a patient&#39;s laptop, patient&#39;s remote, etc.). 
     In any of the foregoing embodiments, the parameters in accordance with which the pulse generator  101  provides signals can be modulated during portions of the therapy regimen. For example, the frequency, amplitude, pulse width and/or signal delivery location can be modulated in accordance with a preset program, patient and/or physician inputs, and/or in a random or pseudorandom manner. Such parameter variations can be used to address a number of potential clinical situations, including changes in the patient&#39;s perception of pain, changes in the preferred target neural population, and/or patient accommodation or habituation. 
     Certain aspects of the foregoing systems and methods may be simplified or eliminated in particular embodiments of the present disclosure. For example, in at least some instances, the therapeutic signals delivered by the system can produce an effect that is much less sensitive to lead location and signal delivery parameters (e.g., amplitude) than are conventional stimulation systems. Accordingly, as noted above, the trial and error process (or parts of this process) for identifying a suitable lead location and associated signal delivery parameters during the lead implant procedure can be eliminated. In addition to or in lieu of this simplification, the post-lead implant trial period can be eliminated. In addition to or in lieu of the foregoing simplifications, the process of selecting signal delivery parameters and administering the signals on a long-term basis can be significantly simplified. Further aspects of these and other expected beneficial results are discussed in greater detail below. 
     2.0 Representative Therapy Parameters 
     Nevro Corporation, the assignee of the present application, has conducted a multi-site clinical study during which multiple patients were first treated with conventional spinal chord stimulation (SCS) techniques, and then with newly developed techniques that are disclosed further below. This study was followed up by a further clinical study focusing on the newly developed techniques, which confirmed and expanded on results obtained during the initial study. Multiple embodiments of the newly developed techniques, therapies and/or systems are referred to as presently disclosed techniques, therapies, and/or systems, or more generally as presently disclosed technologies. 
     2.1. Initial Comparison Study 
     Prior to the initial clinical study, selected patients were identified as suffering from primary chronic low back pain (e.g., neuropathic pain, and/or nociceptive pain, and/or other types of pain, depending upon the patient), either alone or in combination with pain affecting other areas, typically the patient&#39;s leg(s). In all cases, the low back pain was dominant. During the study, the patients were outfitted with two leads, each implanted in the spinal region in a manner generally similar to that shown in  FIG. 1A . One lead was implanted on one side of the spinal cord midline  189 , and the other lead was implanted on the other side of the spinal cord midline  189 .  FIG. 1  B is a cross-sectional illustration of the spinal cord  191  and an adjacent vertebra  195  (based generally on information from Crossman and Neary, “Neuroanatomy,” 1995 (published by Churchill Livingstone)), along with the locations at which leads  110  were implanted in a representative patient. The spinal cord  191  is situated between a ventrally located ventral body  196  and the dorsally located transverse process  198  and spinous process  197 . Arrows V and D identify the ventral and dorsal directions, respectively. The spinal cord  191  itself is located within the dura mater  199 , which also surrounds portions of the nerves exiting the spinal cord  191 , including the dorsal roots  193  and dorsal root ganglia  194 . The leads  110  were positioned just off the spinal cord midline  189  (e.g., about  1  mm. offset) in opposing lateral directions so that the two leads  110  were spaced apart from each other by about  2  mm. 
     Patients with the leads  110  located as shown in  FIG. 1B  initially had the leads positioned at vertebral levels T 7 -T 8 . This location is typical for standard SCS treatment of low back pain because it has generally been the case that at lower (inferior) vertebral levels, standard SCS treatment produces undesirable side effects, and/or is less efficacious. Such side effects include unwanted muscle activation and/or pain. Once the leads  110  were implanted, the patients received standard SCS treatment for a period of five days. This treatment included stimulation at a frequency of less than 1500 Hz (e.g., 60-80 Hz), a pulse width of 100-200 psec, and a duty cycle of 100%. The amplitude of the signal (e.g., the current amplitude) was varied from about 3 mA to about 10 mA. The amplitude was initially established during the implant procedure. The amplitude was then changed by the patient on an as-desired basis during the course of the study, as is typical for standard SCS therapies. 
     After the patient completed the standard SCS portion of the study, the patient then received modulation in accordance with the presently disclosed techniques. One aspect of these techniques included moving the leads  110  inferiorly, so as to be located at vertebral levels T 9 , T 10 , T 11 , and/or T 12 . After the leads  110  were repositioned, the patient received therapeutic signals at a frequency of from about 3 kHz to about 10 kHz. In particular cases, the therapy was applied at 8 kHz, 9 kHz or 10 kHz. These frequencies are significantly higher than the frequencies associated with standard SCS, and accordingly, modulation at these and other representative frequencies (e.g., from about 1.5 kHz to about 100 kHz) is occasionally referred to herein as high frequency modulation. The modulation was applied generally at a duty cycle of from about 50% to about 100%, with the modulation signal on for a period of from about 1 msec. to about 2 seconds, and off for a period of from about 1 msec. to about 1.5 seconds. The width of the applied pulses was about 30-35 μsec., and the amplitude generally varied from about 1 mA to about 4 mA (nominally about 2.5 mA). Modulation in accordance with the foregoing parameters was typically applied to the patients for a period of about four days during the initial clinical study. 
       FIGS. 2-6A  graphically illustrate summaries of the clinical results obtained by testing patients in accordance with the foregoing parameters.  FIG. 2  is a bar chart illustrating the patients&#39; Visual Analog Scale (VAS) pain score for a variety of conditions. The scores indicated in  FIG. 2  are for overall pain. As noted above, these patients suffered primarily from low back pain and accordingly, the pain scores for low back pain alone were approximately the same as those shown in  FIG. 2 . Each of the bars represents an average of the values reported by the multiple patients involved in this portion of the study. Bars  201  and  202  illustrate a baseline pain level of 8.7 for the patients without the benefit of medication, and a baseline level of 6.8 with medication, respectively. After receiving a lead implant on day zero of the study, and initiating high frequency modulation in accordance with the foregoing parameters, patients reported an average pain score of about 4.0, as represented by bar  203 . Over the course of the next three days, (represented by bars  204 - 213 ) the patients recorded pain levels in a diary every morning, midday and evening, as indicated by the correspondingly labeled bars in  FIG. 2 . In addition, pain levels were recorded daily by the local center research coordinator on case report forms (CRFs) as indicated by the correspondingly labeled bars in  FIG. 2 . During this time period, the patients&#39; average pain score gradually decreased to a reported minimum level of about 2.2 (represented by bars  212  and  213 ). 
     For purposes of comparison, bar  214  illustrates the pain score for the same patients receiving standard SCS therapy earlier in the study. Bar  214  indicates that the average pain value for standard SCS therapy was 3.8. Unlike the results of the presently disclosed therapy, standard SCS therapy tended to produce relatively flat patient pain results over the course of several days. Comparing bars  213  and  214 , the clinical results indicate that the presently disclosed therapy reduced pain by 42% when compared with standard SCS therapy. 
     Other pain indices indicated generally consistent results. On the Oswestry Disability Index, average scores dropped from a baseline value of 54 to a value of 33, which is equivalent to a change from “severe disability” to “moderate disability”. Patients&#39; global improvement scores ranked 1.9 on a scale of 1 (“very much improved”) to 7 (“very much worse”). 
     In addition to obtaining greater pain relief with the presently disclosed therapy than with standard SCS therapy, patients experienced other benefits as well, described further below with reference to  FIGS. 3-5C .  FIG. 3  is a bar chart illustrating the number of times per day that the patients initiated modulation changes. Results are illustrated for standard SCS therapy (bar  301 ) and the presently disclosed therapy (bar  302 ). The patient-initiated modulation changes were generally changes in the amplitude of the applied signal, and were initiated by the patient via an external modulator or remote, such as was described above with reference to  FIG. 1A . Patients receiving standard SCS therapy initiated changes to the signal delivery parameters an average of 44 times per day. The initiated changes were typically triggered when the patient changed position, activity level, and/or activity type, and then experienced a reduction in pain relief and/or an unpleasant, uncomfortable, painful, unwanted or unexpected sensation from the therapeutic signal. Patients receiving the presently disclosed therapy did not change the signal delivery parameters at all, except at the practitioners&#39; request. In particular, the patients did not change signal amplitude to avoid painful stimulation. Accordingly,  FIG. 3  indicates that the presently disclosed therapy is significantly less sensitive to lead movement, patient position, activity level and activity type than is standard SCS therapy. 
       FIG. 4  is a bar graph illustrating activity scores for patients receiving the presently disclosed therapy. The activity score is a quality of life score indicating generally the patients&#39; level of satisfaction with the amount of activity that they are able to undertake. As indicated in  FIG. 4 , bar  401  identifies patients having a score of 1.9 (e.g., poor to fair) before beginning therapy. The score improved over time (bars  402 - 404 ) so that at the end of the second day of therapy, patients reported a score of nearly 3 (corresponding to a score of “good”). It is expected that in longer studies, the patients&#39; score may well improve beyond the results shown in  FIG. 4 . Even the results shown in  FIG. 4 , however, indicate a 53% improvement (compared to baseline) in the activity score for patients receiving the presently disclosed therapy over a three day period. Anecdotally, patients also indicated that they were more active when receiving the presently disclosed therapy than they were when receiving standard SCS therapy. Based on anecdotal reports, it is expected that patients receiving standard SCS therapy would experience only a 10-15% improvement in activity score over the same period of time. 
       FIG. 5A  is a bar chart illustrating changes in activity score for patients receiving the presently disclosed therapy and performing six activities: standing, walking, climbing, sitting, riding in a car, and eating. For each of these activities, groups of bars (with individual groups identified by reference numbers  501 ,  502 ,  503  . . .  506 ) indicate that the patients&#39; activity score generally improved over the course of time. These results further indicate that the improvement in activity was broad-based and not limited to a particular activity. Still further, these results indicate a significant level of improvement in each activity, ranging from 30% for eating to 80%-90% for standing, walking and climbing stairs. Anecdotally, it is expected that patients receiving standard SCS treatment would experience only about 10%-20% improvement in patient activity. Also anecdotally, the improvement in activity level was directly observed in at least some patients who were hunched over when receiving standard SCS treatment, and were unable to stand up straight. By contrast, these patients were able to stand up straight and engage in other normal activities when receiving the presently disclosed therapy. 
     The improvement experienced by the patients is not limited to improvements in activity but also extends to relative inactivity, including sleep. For example, patients receiving standard SCS therapy may establish a signal delivery parameter at a particular level when lying prone. When the patient rolls over while sleeping, the patient may experience a significant enough change in the pain reduction provided by standard SCS treatments to cause the patient to wake. In many cases, the patient may additionally experience pain generated by the SCS signal itself, on top of the pain the SCS signal is intended to reduce. With the presently disclosed techniques, by contrast, this undesirable effect can be avoided.  FIGS. 5B and 5C  illustrate the average effect on sleep for clinical patients receiving the presently disclosed therapy.  FIG. 5B  illustrates the reduction in patient disturbances, and  FIG. 5C  illustrates the increase in number of hours slept. In other embodiments, the patient may be able to perform other tasks with reduced pain. For example, patients may drive without having to adjust the therapy level provided by the implanted device. Accordingly, the presently disclosed therapy may be more readily used by patients in such situations and/or other situations that improve the patients&#39; quality of life. 
     Based on additional patient feedback, every one of the tested patients who received the presently disclosed therapy at the target location (e.g., who received the presently disclosed therapy without the lead migrating significantly from its intended location) preferred the presently disclosed therapy to standard SCS therapy. In addition, irrespective of the level of pain relief the patients received, 88% of the patients preferred the presently disclosed therapy to standard SCS therapy because it reduced their pain without creating paresthesia. This indicates that while patients may prefer paresthesia to pain, a significant majority prefer no sensation to both pain and paresthesia. This result, obtained via the presently disclosed therapy, is not available with standard SCS therapies that are commonly understood to rely on paresthesia (i.e., masking) to produce pain relief. 
     Still further, anecdotal data indicate that patients receiving the presently disclosed therapy experienced less muscle capture than they experienced with standard SCS. In particular, patients reported a lack of spasms, cramps, and muscle pain, some or all of which they experienced when receiving standard SCS. Patients also reported no interference with volitional muscle action, and instead indicated that they were able to perform motor tasks unimpeded by the presently disclosed therapy. Still further, patients reported no interference with other sensations, including sense of touch (e.g., detecting vibration), temperature and proprioception. In most cases, patients reported no interference with nociceptive pain sensation. However, in some cases, patients reported an absence of incision pain (associated with the incision used to implant the signal delivery lead) or an absence of chronic peripheral pain (associated with arthritis). Accordingly, in particular embodiments, aspects of the currently disclosed techniques may be used to address nociceptive pain, including acute peripheral pain, and/or chronic peripheral pain. For example, in at least some cases, patients with low to moderate nociceptive pain received relief as a result of the foregoing therapy. Patients with more severe/chronic nociceptive pain were typically not fully responsive to the present therapy techniques. This result may be used in a diagnostic setting to distinguish the types of pain experienced by the patients, as will be discussed in greater detail later. 
       FIG. 6A  is a bar chart indicating the number of successful therapeutic outcomes as a function of the location (indicated by vertebral level) of the active contacts on the leads that provided the presently disclosed therapy. In some cases, patients obtained successful outcomes when modulation was provided at more than one vertebral location. As indicated in  FIG. 6A , successful outcomes were obtained over a large axial range (as measured in a superior-inferior direction along the spine) from vertebral bodies T 9  to T 12 . This is a surprising result in that it indicates that while there may be a preferred target location (e.g., around T 10 ), the lead can be positioned at a wide variety of locations while still producing successful results. In particular, neighboring vertebral bodies are typically spaced apart from each other by approximately 32 millimeters (depending on specific patient anatomy), and so successful results were obtained over a broad range of four vertebral bodies (about 128 mm.) and a narrower range of one to two vertebral bodies (about 32-64 mm.). By contrast, standard SCS data generally indicate that the therapy may change from effective to ineffective with a shift of as little as 1 mm. in lead location. As will be discussed in greater detail later, the flexibility and versatility associated with the presently disclosed therapy can produce significant benefits for both the patient and the practitioner. 
       FIGS. 6B and 6C  are flow diagrams illustrating methods for treating patients in accordance with particular embodiments of the present disclosure. Manufacturers or other suitable entities can provide instructions to practitioners for executing these and other methods disclosed herein. Manufacturers can also program devices of the disclosed systems to carry out at least some of these methods.  FIG. 6B  illustrates a method  600  that includes implanting a signal generator in a patient (block  610 ). The signal generator can be implanted at the patient&#39;s lower back or other suitable location. The method  600  further includes implanting a signal delivery device (e.g., a lead, paddle or other suitable device) at the patient&#39;s spinal cord region (block  620 ). This portion of the method can in turn include implanting the device (e.g., active contacts of the device) at a vertebral level ranging from about T 9  to about T 12  (e.g., about T 9 -T 12 , inclusive) (block  621 ), and at a lateral location ranging from the spinal cord midline to the DREZ, inclusive (block  622 ). At block  630 , the method includes applying a high frequency waveform, via the signal generator and the signal delivery device. In particular examples, the frequency of the signal (or at least a portion of the signal) can be from about 1.5 kHz to about 100 kHz, or from about 1.5 kHz to about 50 kHz., or from about 3 kHz to about 20 kHz, or from about 3 kHz to about 15 kHz, or from about 5 kHz to about 15 kHz, or from about 3 kHz to about 10 kHz. The method  600  further includes blocking, suppressing, inhibiting or otherwise reducing the patient&#39;s pain, e.g., chronic low back pain (block  640 ). This portion of the method can in turn include reducing pain without unwanted sensory effects and/or limitations (block  641 ), and/or without motor effects (block  642 ). For example, block  641  can include reducing or eliminating pain without reducing patient perception of other sensations, and/or without triggering additional pain. Block  642  can include reducing or eliminating pain without triggering muscle action and/or without interfering with motor signal transmission. 
       FIG. 6C  illustrates a method  601  that includes features in addition to those described above with reference to  FIG. 6B . For example, the process of applying a high frequency waveform (block  630 ) can include doing so over a wide amplitude range (e.g., from less than 1 mA up to about 8 mA in one embodiment, and up to about 6 mA and about 5 mA, respectively, in other embodiments) without creating unwanted side effects, such as undesirable sensations and/or motor interference (block  631 ). In another embodiment, the process of applying a high frequency waveform can include applying the waveform at a fixed amplitude (block  632 ). As described further later, each of these aspects can provide patient and/or practitioner benefits. 
     The process of blocking, suppressing or otherwise reducing patient pain (block  640 ) can include doing so without creating paresthesia (block  643 ), or in association with a deliberately generated paresthesia (block  644 ). As noted above, clinical results indicate that most patients prefer the absence of paresthesia to the presence of paresthesia, e.g., because the sensation of paresthesia may change to an uncomfortable or painful sensation when the patient changes position and/or adjusts the signal amplitude. However, in some cases, patients may prefer the sensation of paresthesia (e.g., patients who have previously received SCS), and so can have the option of receiving it. Further details of methodologies that include combinations of paresthesia-inducing modulation and non-paresthesia-inducing modulation are included in U.S. application Ser. No. 12/765,685, incorporated herein by reference. In other cases, paresthesia may be used by the practitioner for site selection (e.g., to determine the location at which active electrodes are positioned). In addition to the above, reducing patient pain can include doing so with relative insensitivity to patient attributes that standard SCS is normally highly sensitive to (block  645 ). These attributes can include patient movement (block  646 ) and/or patient position (block  647 ). 
     2.2. Follow-On Study 
     Nevro Corporation, the assignee of the present application, has conducted a follow-on study to evaluate particular parameters and results of the therapy described above. In the follow-on study, patients received implanted leads and simulators, and received therapy over a period of several months. This study did not include a direct comparison with conventional SCS techniques for each patient, though some of the patients received conventional SCS therapy prior to receiving modulation in accordance with the present technology. Selected results are described further below. 
       FIG. 7A  is a schematic illustration of a typical lead placement used during the follow-on study. In this study, two leads  111  (shown as a first lead  111   a  and a second lead  111   b ) were positioned generally end-to-end to provide a modulation capability that extends over several vertebral levels of the patients&#39; spine. The leads  111   a,    111   b  were positioned to overlap slightly, to account for possible shifts in lead location. During the course of the therapy, contacts C of the two leads  111   a,    111   b  were activated on one lead at a time. In other words, the contacts C of only one lead  111  were active at any one time, and signals were not directed between the contacts C located on different leads  111 . While two leads were used during the clinical study, it is expected that in general use, a single lead can be positioned at the appropriate vertebral level. The lead can have more widely spaced contacts to achieve the same or similar effects as those described herein as will be described in greater detail below with reference to  FIG. 9 . 
     The contacts C of each lead  111   a,    111   b  have a width W 2  of approximately 3 mm, and are separated from each other by a distance D 1  of approximately 1 mm. Accordingly, the center-to-center spacing S between neighboring contacts C is approximately  4  mm. The leads  111   a,    111   b  were positioned at or close to the patients&#39; spinal midline  189 . Typically, one lead was positioned on one side of the midline  189 , and the other lead was positioned on the other side of the patients&#39; midline  189 . During the course of the study, several significant effects were observed. For example, the leads  111   a,    111   b  could be positioned at any of a variety of locations within a relatively wide window W 1  having an overall width of ±3-5 mm from the midline  189  (e.g., an overall width of 6-10 mm), without significantly affecting the efficacy of the treatment. In addition, patients with bilateral pain (e.g., on both sides of the midline  189 ) reported bilateral relief, independent of the lateral location of the leads  110   a,    110   b.  For example, patients having a lead located within the window W 1  on one side of the midline  189  reported pain relief on the opposite side of the midline  189 . This is unlike conventional SCS therapies, for which bilateral relief, when it is obtained at all, is generally very sensitive to any departure from a strictly midline lead location. Still further, the distance between neighboring active contacts was significantly greater than is typical for standard SCS. Practitioners were able to “skip” (e.g., deactivate) several consecutive contacts so that neighboring active contacts had a center-to-center spacing of, for example,  20  mm, and an edge-to-edge spacing of, for example, 17 mm. In addition, patients were relatively insensitive to the axial location of the active contacts. For example, practitioners were able to establish the same or generally the same levels of pain relief over a wide range of contact spacings that is expected to extend up to two vertebral bodies (e.g., about 64 mm). Yet further, the practitioners obtained a similar therapeutic effect whether a given contact was identified as cathodic or anodic, as is described in greater detail later. 
     For most patients in the follow-on study, the leads were implanted at the T 9 -T 10  vertebral locations. These patients typically experienced primarily low back pain prior to receiving the therapy, though some experienced leg pain as well. Based on the results obtained during the follow-on study and the initial study, it is expected that the overall vertebral location range for addressing low back pain is from about T 9  to about T 12 . It is further expected that within this range, modulation at T 12  or T 11 -T 12  may more effectively treat patients with both low back and leg pain. However, in some cases, patients experienced greater leg pain relief at higher vertebral locations (e.g., T 9 -T 10 ) and in still further particular cases, modulation at T 9  produced more leg pain relief than modulation at T 10 . Accordingly, within the general ranges described above, particular patients may have physiological characteristics or other factors that produce corresponding preferred vertebral locations. 
     Patients receiving treatment in the follow-on study received a square-wave signal at a frequency of about 10 kHz. Patients received modulation at a 100% duty cycle, with an initial current amplitude (bi-phasic) of about 2 mA. Patients and practitioners were able to adjust the signal amplitude, typically up to about 5 mA. At any of the foregoing levels, the signal pulses are expected to be suprathreshold, meaning that they can trigger an action potential in the target neural population, independent of any intrinsic neural activity at the target neural population. 
     Patients in the follow-on study were evaluated periodically after the modulation system  100  was implanted and activated. The VAS scores reported by these patients after 30 days of receiving treatment averaged about 1.0, indicating that the trend discussed above with respect to  FIG. 2  continued for some period of time. At least some of these patients reported an increase in the VAS score up to level of about 2.25. It is expected that this increase resulted from the patients&#39; increased activity level. Accordingly, it is not believed that this increase indicates a reduction in the efficacy of the treatment, but rather, indicates an effective therapy that allows patients to engage in activities they otherwise would not. 
       FIG. 7B  illustrates overall Oswestry scores for patients engaging in a variety of activities and receiving modulation in accordance with the follow-on study protocol. A score of  100  corresponds to a completely disabled condition, and a score of  0  corresponds to no disability. These scores indicate a general improvement over time, for example, consistent with and in fact improved over results from in the initial study. In addition, several patients reported no longer needing or using canes or wheelchairs after receiving therapy in accordance with the foregoing embodiments. 
     Results from the follow-on study confirm a relative insensitivity of the therapeutic effectiveness of the treatment to changes in current amplitude. In particular, patients typically received modulation at a level of from about 2.0 mA to about 3.5 mA. In most cases, patients did not report significant changes in pain reduction when they changed the amplitude of the applied signal. Patients were in several cases able to increase the current amplitude up to a level of about 5 mA before reporting undesirable side effects. In addition, the side effects began to take place in a gradual, rather than a sudden, manner. Anecdotal feedback from some patients indicated that at high amplitudes (e.g., above 5 mA) the treatment efficacy began to fall off, independent of the onset of any undesirable side effects. It is further expected that patients can receive effective therapy at current amplitudes of less than 2 mA. This expectation is based at least in part on data indicating that reducing the duty cycle (e.g., to 70%) did not reduce efficacy. 
     The results of the follow-on study also indicated that most patients (e.g., approximately 80% of the patients) experienced at least satisfactory pain reduction without changing any aspect of the signal delivery parameters (e.g., the number and/or location of active contacts, and/or the current amplitude), once the system was implanted and activated. A small subset of the patients (e.g., about 20%) benefited from an increased current amplitude when engaging in particular activities, and/or benefited from a lower current amplitude when sleeping. For these patients, increasing the signal amplitude while engaging in activity produced a greater degree of pain relief, and reducing the amplitude at night reduced the likelihood of over-stimulation, while at the same time saving power. In a representative example, patients selected from between two such programs: a “strong” program which provided signals at a relatively high current amplitude (e.g., from about 1 mA to about 6 mA), and a “weak” program which provided signals at a lower current amplitude (e.g., from about 0.1 mA to about 3 mA). 
     Another observed effect during the follow-on study was that patients voluntarily reduced their intake of opioids and/or other pain medications that they had been receiving to address pain prior to receiving modulation in accordance with the present technology. The patients&#39; voluntary drug intake reduction is expected to be a direct result of the decreased need for the drugs, which is in turn a direct result of the modulation provided in accordance with the present technology. However, due to the addictive nature of opioids, the ease with which patients voluntarily gave up the use of opioids was surprising. Therefore, it is also expected that for at least some patients, the present technology, in addition to reducing pain, acted to reduce the chemical dependency on these drugs. Accordingly, it is further expected that in at least some embodiments, therapeutic techniques in accordance with the present disclosure may be used to reduce or eliminate patient chemical dependencies, independent of whether the patients also have and/or are treated for low back pain. 
     Patients entering the follow-on study typically experienced neuropathic pain, nociceptive pain, or a combination of neuropathic pain and nociceptive pain. Neuropathic pain refers generally to pain resulting from a dysfunction in the neural mechanism for reporting pain, which can produce a sensation of pain without an external neural trigger. Nociceptive pain refers generally to pain that is properly sensed by the patient as being triggered by a particular mechanical or other physical effect (e.g., a slipped disc, a damaged muscle, or a damaged bone). In general, neuropathic pain is consistent, and nociceptive pain fluctuates, e.g., with patient position or activity. In at least some embodiments, treatment in accordance with the present technology appears to more effectively address neuropathic pain than nociceptive pain. For example, patients who reported low levels of pain fluctuation before entering treatment (indicating predominantly neuropathic pain), received greater pain relief during treatment than patients whose pain fluctuated significantly. In two particular cases, the therapy did not prove to be effective, and it is believe that this resulted from a mechanical issue with the patients&#39; back anatomy, which identified the patients as better candidates for surgery than for the present therapy. Accordingly, in addition to addressing neuropathic pain and (in at least some cases), nociceptive pain, techniques in accordance with the present technology may also act as a screening tool to identify patients who suffer primarily from nociceptive pain rather than neuropathic pain. For example, the practitioner can make such an identification based at least in part on feedback from the patient corresponding to the existence and/or amount (including amount of fluctuation) of pain reduction when receiving signals in accordance with the present technology. As a result of using this diagnostic technique, these patients can be directed to surgical or other procedures that can directly address the nociceptive pain. In particular, patients may receive signals in accordance with the present technology and, if these patients are unresponsive, may be suitable candidates for surgical intervention. Of course, if the patients are responsive, they can continue to receive signals in accordance with the present technology as therapy 
     3.0 Mechanisms of Action 
       FIG. 8  is a schematic diagram (based on Linderoth and Foreman, “Mechanisms of Spinal Cord Stimulation in Painful Syndromes: Role of Animal Models,” Pain Medicine, Vol. 51, 2006) illustrating an expected mechanism of action for standard SCS treatment, along with potential mechanisms of action for therapy provided in accordance with embodiments of the present technology. When a peripheral nerve is injured, it is believed that the Aδ and C nociceptors provide an increased level of excitatory transmitters to second order neurons at the dorsal horn of the spinal cord. Standard SCS therapy, represented by arrow  701 , is expected to have two effects. One effect is an orthodromic effect transmitted along the dorsal column to the patient&#39;s brain and perceived as paresthesia. The other is an antidromic effect that excites the interneuron pool, which in turn inhibits inputs to the second order neurons. 
     One potential mechanism of action for the presently disclosed therapy is represented by arrow  710 , and includes producing an incomplete conduction block (e.g., an incomplete block of afferent and/or efferent signal transmission) at the dorsal root level. This block may occur at the dorsal column, dorsal horn, and/or dorsal root entry zone, in addition to or in lieu of the dorsal root. In any of these cases, the conduction block is selective to and/or preferentially affects the smaller Aδ and/or C fibers and is expected to produce a decrease in excitatory inputs to the second order neurons, thus producing a decrease in pain signals supplied along the spinal thalamic tract. 
     Another potential mechanism of action (represented by arrow  720  in  FIG. 8 ) includes more profoundly activating the interneuron pool and thus increasing the inhibition of inputs into the second order neurons. This can, in effect, potentially desensitize the second order neurons and convert them closer to a normal state before the effects of the chronic pain associated signals have an effect on the patient. 
     Still another potential mechanism of action relates to the sensitivity of neurons in patients suffering from chronic pain. In such patients, it is believed that the pain-transmitting neurons may be in a different, hypersensitive state compared to the same neurons in people who do not experience chronic pain, resulting in highly sensitized cells that are on a “hair trigger” and fire more frequently and at different patterns with a lower threshold of stimulation than those cells of people who do not experience chronic pain. As a result, the brain receives a significantly increased volume of action potentials at significantly altered transmission patterns. Accordingly, a potential mechanism of action by which the presently disclosed therapies may operate is by reducing this hypersensitivity by restoring or moving the “baseline” of the neural cells in chronic pain patients toward the normal baseline and firing frequency of non-chronic pain patients. This effect can in turn reduce the sensation of pain in this patient population without affecting other neural transmissions (for example, touch, heat, etc.). 
     The foregoing mechanisms of action are identified here as possible mechanisms of action that may account for the foregoing clinical results. In particular, these mechanisms of action may explain the surprising result that pain signals transmitted by the small, slow Aδ and C fibers may be inhibited without affecting signal transmission along the larger, faster Aβ fibers. This is contrary to the typical results obtained via standard SCS treatments, during which modulation signals generally affect Aβ fibers at low amplitudes, and do not affect Aβ and C fibers until the signal amplitude is so high as to create pain or other unwanted effects transmitted by the Aβ fibers. However, aspects of the present disclosure need not be directly tied to such mechanisms. In addition, aspects of both the two foregoing proposed mechanisms may in combination account for the observed results in some embodiments, and in other embodiments, other mechanisms may account for the observed results, either alone or in combination with either one of the two foregoing mechanisms. One such mechanism includes an increased ability of high frequency modulation (compared to standard SCS stimulation) to penetrate through the cerebral spinal fluid (CSF) around the spinal cord. Another such mechanism is the expected reduction in impedance presented by the patient&#39;s tissue to high frequencies, as compared to standard SCS frequencies. Still another such mechanism is the ability of high frequency signal to elicit an asynchronous neural response, as disclosed in greater detail in pending U.S. application Ser. No. 12/362,244, filed on Jan. 29, 2009 and incorporated herein by reference. Although the higher frequencies associated with the presently disclosed techniques may initially appear to require more power than conventional SCS techniques, the signal amplitude may be reduced when compared to conventional SCS values (due to improved signal penetration) and/or the duty cycle may be reduced (due to persistence effects described later). Accordingly, the presently disclosed techniques can result in a net power savings when compared with standard SCS techniques. 
     4.0 Expected Benefits Associated With Certain Embodiments 
     Certain of the foregoing embodiments can produce one or more of a variety of advantages, for the patient and/or the practitioner, when compared with standard SCS therapies. Some of these benefits were described above. For example, the patient can receive effective pain relief without patient-detectable disruptions to normal sensory and motor signals along the spinal cord. In particular embodiments, while the therapy may create some effect on normal motor and/or sensory signals, the effect is below a level that the patient can reliably detect intrinsically, e.g., without the aid of external assistance via instruments or other devices. Accordingly, the patient&#39;s levels of motor signaling and other sensory signaling (other than signaling associated with the target pain) can be maintained at pre-treatment levels. For example, as described above, the patient can experience a significant pain reduction that is largely independent of the patient&#39;s movement and position. In particular, the patient can assume a variety of positions and/or undertake a variety of movements associated with activities of daily living and/or other activities, without the need to adjust the parameters in accordance with which the therapy is applied to the patient (e.g., the signal amplitude). This result can greatly simplify the patient&#39;s life and reduce the effort required by the patient to experience pain relief while engaging in a variety of activities. This result can also provide an improved lifestyle for patients who experience pain during sleep, as discussed above with reference to  FIGS. 5B and 5C . 
     Even for patients who receive a therapeutic benefit from changes in signal amplitude, the foregoing therapy can provide advantages. For example, such patients can choose from a limited number of programs (e.g., two or three) each with a different amplitude and/or other signal delivery parameter, to address some or all of the patient&#39;s pain. In one such example, the patient activates one program before sleeping and another after waking. In another such example, the patient activates one program before sleeping, a second program after waking, and a third program before engaging in particular activities that would otherwise cause pain. This reduced set of patient options can greatly simplify the patient&#39;s ability to easily manage pain, without reducing (and in fact, increasing) the circumstances under which the therapy effectively addresses pain. In any embodiments that include multiple programs, the patient&#39;s workload can be further reduced by automatically detecting a change in patient circumstance, and automatically identifying and delivering the appropriate therapy regimen. Additional details of such techniques and associated systems are disclosed in co-pending U.S. application Ser. No. 12/703,683, incorporated herein by reference. 
     Another benefit observed during the clinical studies described above is that when the patient does experience a change in the therapy level, it is a gradual change. This is unlike typical changes associated with conventional SCS therapies. With conventional SCS therapies, if a patient changes position and/or changes an amplitude setting, the patient can experience a sudden onset of pain, often described by patients as unbearable. By contrast, patients in the clinical studies described above, when treated with the presently disclosed therapy, reported a gradual onset of pain when signal amplitude was increased beyond a threshold level, and/or when the patient changed position, with the pain described as gradually becoming uncomfortable. One patient described a sensation akin to a cramp coming on, but never fully developing. This significant difference in patient response to changes in signal delivery parameters can allow the patient to more freely change signal delivery parameters and/or posture when desired, without fear of creating an immediately painful effect. 
     Another observation from the clinical studies described above is that the amplitude “window” between the onset of effective therapy and the onset of pain or discomfort is relatively broad, and in particular, broader than it is for standard SCS treatment. For example, during standard SCS treatment, the patient typically experiences a pain reduction at a particular amplitude, and begins experiencing pain from the therapeutic signal (which may have a sudden onset, as described above) at from about 1.2 to about 1.6 times that amplitude. This corresponds to an average dynamic range of about 1.4. In addition, patients receiving standard SCS stimulation typically wish to receive the stimulation at close to the pain onset level because the therapy is often most effective at that level. Accordingly, patient preferences may further reduce the effective dynamic range. By contrast, therapy in accordance with the presently disclosed technology resulted in patients obtaining pain relief at 1 mA or less, and not encountering pain or muscle capture until the applied signal had an amplitude of 4 mA, and in some cases up to about 5 mA, 6 mA, or 8 mA, corresponding to a much larger dynamic range (e.g., larger than 1.6 or 60% in some embodiments, or larger than 100% in other embodiments). Even at the forgoing amplitude levels, the pain experienced by the patients was significantly less than that associated with standard SCS pain onset. An expected advantage of this result is that the patient and practitioner can have significantly wider latitude in selecting an appropriate therapy amplitude with the presently disclosed methodology than with standard SCS methodologies. For example, the practitioner can increase the signal amplitude in an effort to affect more (e.g., deeper) fibers at the spinal cord, without triggering unwanted side effects. The existence of a wider amplitude window may also contribute to the relative insensitivity of the presently disclosed therapy to changes in patient posture and/or activity. For example, if the relative position between the implanted lead and the target neural population changes as the patient moves, the effective strength of the signal when it reaches the target neural population may also change. When the target neural population is insensitive to a wider range of signal strengths, this effect can in turn allow greater patient range of motion without triggering undesirable side effects. 
     Although the presently disclosed therapies may allow the practitioner to provide modulation over a broader range of amplitudes, in at least some cases, the practitioner may not need to use the entire range. For example, as described above, the instances in which the patient may need to adjust the therapy may be significantly reduced when compared with standard SCS therapy because the presently disclosed therapy is relatively insensitive to patient position, posture and activity level. In addition to or in lieu of the foregoing effect, the amplitude of the signals applied in accordance with the presently disclosed techniques may be lower than the amplitude associated with standard SCS because the presently disclosed techniques may target neurons that are closer to the surface of the spinal cord. For example, it is believed that the nerve fibers associated with low back pain enter the spinal cord between T 9  and T 12  (inclusive), and are thus close to the spinal cord surface at these vertebral locations. Accordingly, the strength of the therapeutic signal (e.g., the current amplitude) can be modest because the signal need not penetrate through a significant depth of spinal cord tissue to have the intended effect. Such low amplitude signals can have a reduced (or zero) tendency for triggering side effects, such as unwanted sensory and/or motor responses. Such low amplitude signals can also reduce the power required by the implanted pulse generator, and can therefore extend the battery life and the associated time between recharging and/or replacing the battery. 
     Yet another expected benefit of providing therapy in accordance with the foregoing parameters is that the practitioner need not implant the lead with the same level of precision as is typically required for standard SCS lead placement. For example, while the foregoing results were identified for patients having two leads (one positioned on either side of the spinal cord midline), it is expected that patients will receive the same or generally similar pain relief with only a single lead placed at the midline. Accordingly, the practitioner may need to implant only one lead, rather than two. It is still further expected that the patient may receive pain relief on one side of the body when the lead is positioned offset from the spinal cord midline in the opposite direction. Thus, even if the patient has bilateral pain, e.g., with pain worse on one side than the other, the patient&#39;s pain can be addressed with a single implanted lead. Still further, it is expected that the lead position can vary laterally from the anatomical and/or physiological spinal cord midline to a position 3-5 mm. away from the spinal cord midline (e.g., out to the dorsal root entry zone or DREZ). The foregoing identifiers of the midline may differ, but the expectation is that the foregoing range is effective for both anatomical and physiological identifications of the midline, e.g., as a result of the robust nature of the present therapy. Yet further, it is expected that the lead (or more particularly, the active contact or contacts on the lead) can be positioned at any of a variety of axial locations in a range of about T 9 -T 12  in one embodiment, and a range of one to two vertebral bodies within T 9 -T 12  in another embodiment, while still providing effective treatment. Accordingly, the practitioner&#39;s selected implant site need not be identified or located as precisely as it is for standard SCS procedures (axially and/or laterally), while still producing significant patient benefits. In particular, the practitioner can locate the active contacts within the foregoing ranges without adjusting the contact positions in an effort to increase treatment efficacy and/or patient comfort. In addition, in particular embodiments, contacts at the foregoing locations can be the only active contacts delivering therapy to the patient. The foregoing features, alone or in combination, can reduce the amount of time required to implant the lead, and can give the practitioner greater flexibility when implanting the lead. For example, if the patient has scar tissue or another impediment at a preferred implant site, the practitioner can locate the lead elsewhere and still obtain beneficial results. 
     Still another expected benefit, which can result from the foregoing observed insensitivities to lead placement and signal amplitude, is that the need for conducting a mapping procedure at the time the lead is implanted may be significantly reduced or eliminated. This is an advantage for both the patient and the practitioner because it reduces the amount of time and effort required to establish an effective therapy regimen. In particular, standard SCS therapy typically requires that the practitioner adjust the position of the lead and the amplitude of the signals delivered by the lead, while the patient is in the operating room reporting whether or not pain reduction is achieved. Because the presently disclosed techniques are relatively insensitive to lead position and amplitude, the mapping process can be eliminated entirely. Instead, the practitioner can place the lead at a selected vertebral location (e.g., about T 9 -T 12 ) and apply the signal at a pre-selected amplitude (e.g., 1 to 2 mA), with a significantly reduced or eliminated trial-and-error optimization process (for a contact selection and/or amplitude selection), and then release the patient. In addition to or in lieu of the foregoing effect, the practitioner can, in at least some embodiments, provide effective therapy to the patient with a simple bipole arrangement of electrodes, as opposed to a tripole or other more complex arrangement that is used in existing systems to steer or otherwise direct therapeutic signals. In light of the foregoing effect(s), it is expected that the time required to complete a patient lead implant procedure and select signal delivery parameters can be reduced by a factor of two or more, in particular embodiments. As a result, the practitioner can treat more patients per day, and the patients can more quickly engage in activities without pain. 
     The foregoing effect(s) can extend not only to the mapping procedure conducted at the practitioner&#39;s facility, but also to the subsequent trial period. In particular, patients receiving standard SCS treatment typically spend a week after receiving a lead implant during which they adjust the amplitude applied to the lead in an attempt to establish suitable amplitudes for any of a variety of patient positions and patient activities. Because embodiments of the presently disclosed therapy are relatively insensitive to patient position and activity level, the need for this trial and error period can be reduced or eliminated. 
     Still another expected benefit associated with embodiments of the presently disclosed treatment is that the treatment may be less susceptible to patient habituation. In particular, it is expected that in at least some cases, the high frequency signal applied to the patient can produce an asynchronous neural response, as is disclosed in co-pending U.S. application Ser. No. 12/362,244, previously incorporated herein by reference. The asynchronous response may be less likely to produce habituation than a synchronous response, which can result from lower frequency modulation. 
     Yet another feature of embodiments of the foregoing therapy is that the therapy can be applied without distinguishing between anodic contacts and cathodic contacts. As described in greater detail later, this feature can simplify the process of establishing a therapy regimen for the patient. In addition, due to the high frequency of the waveform, the adjacent tissue may perceive the waveform as a pseudo steady state signal. As a result of either or both of the foregoing effects, tissue adjacent both electrodes may be beneficially affected. This is unlike standard SCS waveforms for which one electrode is consistently cathodic and another is consistently anodic. 
     In any of the foregoing embodiments, aspects of the therapy provided to the patient may be varied within or outside the parameters used during the clinical testing described above, while still obtaining beneficial results for patients suffering from chronic low back pain. For example, the location of the lead body (and in particular, the lead body electrodes or contacts) can be varied over the significant lateral and/or axial ranges described above. Other characteristics of the applied signal can also be varied. For example, as described above, the signal can be delivered at a frequency of from about 1.5 kHz to about 100 kHz, and in particular embodiments, from about 1.5 kHz to about 50 kHz. In more particular embodiments, the signal can be provided at frequencies of from about 3 kHz to about 20 kHz, or from about 3 kHz to about 15 kHz, or from about 5 kHz to about 15 kHz, or from about 3 kHz to about 10 kHz. The amplitude of the signal can range from about 0.1 mA to about 20 mA in a particular embodiment, and in further particular embodiments, can range from about 0.5 mA to about 10 mA, or about 0.5 mA to about 4 mA, or about 0.5 mA to about 2.5 mA. The amplitude of the applied signal can be ramped up and/or down. In particular embodiments, the amplitude can be increased or set at an initial level to establish a therapeutic effect, and then reduced to a lower level to save power without forsaking efficacy, as is disclosed in pending U.S. application Ser. No. 12/264,836, filed Nov. 4, 2008, and incorporated herein by reference. In particular embodiments, the signal amplitude refers to the electrical current level, e.g., for current-controlled systems. In other embodiments, the signal amplitude can refer to the electrical voltage level, e.g., for voltage-controlled systems. The pulse width (e.g., for just the cathodic phase of the pulses) can vary from about 10 microseconds to about 333 microseconds. In further particular embodiments, the pulse width can range from about 25 microseconds to about 166 microseconds, or from about 33 microseconds to about 100 microseconds, or from about 50 microseconds to about 166 microseconds. The specific values selected for the foregoing parameters may vary from patient to patient and/or from indication to indication and/or on the basis of the selected vertebral location. In addition, the methodology may make use of other parameters, in addition to or in lieu of those described above, to monitor and/or control patient therapy. For example, in cases for which the pulse generator includes a constant voltage arrangement rather than a constant current arrangement, the current values described above may be replaced with corresponding voltage values. 
     In at least some embodiments, it is expected that the foregoing amplitudes will be suprathreshold. It is also expected that, in at least some embodiments, the neural response to the foregoing signals will be asynchronous, as described above. Accordingly, the frequency of the signal can be selected to be higher (e.g., between two and ten times higher) than the refractory period of the target neurons at the patient&#39;s spinal cord, which in at least some embodiments is expected to produce an asynchronous response. 
     Patients can receive multiple signals in accordance with still further embodiments of the disclosure. For example, patients can receive two or more signals, each with different signal delivery parameters. In one particular example, the signals are interleaved with each other. For instance, the patient can receive 5 kHz pulses interleaved with 10 kHz pulses. In other embodiments, patients can receive sequential “packets” of pulses at different frequencies, with each packet having a duration of less than one second, several seconds, several minutes, or longer depending upon the particular patient and indication. 
     In still further embodiments, the duty cycle may be varied from the 50%-100% range of values described above, as can the lengths of the on/off periods. For example, it has been observed that patients can have therapeutic effects (e.g., pain reduction) that persist for significant periods after the modulation has been halted. In particular examples, the beneficial effects can persist for 10-20 minutes in some cases, and up to an hour in others and up to a day or more in still further cases. Accordingly, the simulator can be programmed to halt modulation for periods of up to an hour, with appropriate allowances for the time necessary to re-start the beneficial effects. This arrangement can significantly reduce system power consumption, compared to systems with higher duty cycles, and compared to systems that have shorter on/off periods. 
     5.0 Representative Lead Configurations 
       FIG. 9  is a partially schematic illustration of a lead  910  having first and second contacts C 1 , C 2  positioned to deliver modulation signals in accordance with particular embodiments of the disclosure. The contacts are accordingly positioned to contact the patient&#39;s tissue when implanted. The lead  910  can include at least two first contacts Cl and at least two second contacts C 2  to support bipolar modulation signals via each contact grouping. In one aspect of this embodiment, the lead  910  can be elongated along a major or lead axis A, with the contacts C 1 , C 2  spaced equally from the major axis A. In general, the term elongated refers to a lead or other signal delivery element having a length (e.g., along the spinal cord) greater than its width. The lead  910  can have an overall length L (over which active contacts are positioned) that is longer than that of typical leads. In particular, the length L can be sufficient to position first contacts C 1  at one or more vertebral locations (including associated neural populations), and position the second contacts C 2  at another vertebral location (including associated neural populations) that is spaced apart from the first and that is superior the first. For example, the first contacts C 1  may be positioned at vertebral levels T 9 -T 12  to treat low back pain, and the second contacts C 2  may be positioned at superior vertebral locations (e.g., cervical locations) to treat arm pain. Representative lead lengths are from about 30 cm to about 150 cm, and in particular embodiments, from about 40 cm to about 50 cm. Pulses may be applied to both groups of contacts in accordance with several different arrangements. For example pulses provided to one group may be interleaved with pulses applied to the other, or the same signal may be rapidly switched from one group to the other. In other embodiments, the signals applied to individual contacts, pairs of contacts, and/or contacts in different groups may be multiplexed in other manners. In any of these embodiments, each of the contacts C 1 , C 2  can have an appropriately selected surface area, e.g., in the range of from about 3 mm 2  to about 25 mm 2 , and in particular embodiments, from about 8 mm 2  to about 15 mm 2 . Individual contacts on a given lead can have different surface area values, within the foregoing ranges, than neighboring or other contacts of the lead, with values selected depending upon features including the vertebral location of the individual contact. 
     Another aspect of an embodiment of the lead  910  shown in  FIG. 9  is that the first contacts C 1  can have a significantly wider spacing than is typically associated with standard SCS contacts. For example, the first contacts C 1  can be spaced apart (e.g., closest edge to closest edge) by a first distance S 1  that is greater than a corresponding second distance S 2  between immediately neighboring second contacts C 2 . In a representative embodiment, the first distance S 1  can range from about 3 mm up to a distance that corresponds to one-half of a vertebral body, one vertebral body, or two vertebral bodies (e.g., about 16 mm, 32 mm, or 64 mm, respectively). In another particular embodiment, the first distance S 1  can be from about 5 mm to about 15 mm. This increased spacing can reduce the complexity of the lead  910 , and can still provide effective treatment to the patient because, as discussed above, the effectiveness of the presently disclosed therapy is relatively insensitive to the axial location of the signal delivery contacts. The second contacts C 2  can have a similar wide spacing when used to apply high frequency modulation in accordance with the presently disclosed methodologies. However, in another embodiment, different portions of the lead  910  can have contacts that are spaced apart by different distances. For example, if the patient receives high frequency pain suppression treatment via the first contacts C 1  at a first vertebral location, the patient can optionally receive low frequency (e.g., 1500 Hz or less, or 1200 Hz or less), paresthesia-inducing signals at the second vertebral location via the second contacts C 2  that are spaced apart by a distance S 2 . The distance S 2  can be smaller than the distance S 1  and, in particular embodiments, can be typical of contact spacings for standard SCS treatment (e.g., 4 mm spacings), as these contacts may be used for providing such treatment. Accordingly, the first contacts C 1  can deliver modulation in accordance with different signal delivery parameters than those associated with the second contacts C 2 . In still further embodiments, the inferior first contacts C 1  can have the close spacing S 2 , and the superior second contacts C 2  can have the wide spacing S 1 , depending upon patient indications and/or preferences. In still further embodiments, as noted above, contacts at both the inferior and superior locations can have the wide spacing, e.g., to support high frequency modulation at multiple locations along the spinal cord. In other embodiments, the lead  910  can include other arrangements of different contact spacings, depending upon the particular patient and indication. For example, the widths of the second contacts C 2  (and/or the first contacts C 1 ) can be a greater fraction of the spacing between neighboring contacts than is represented schematically in  FIG. 9 . The distance S 1  between neighboring first contacts C 1  can be less than an entire vertebral body (e.g., 5 mm or 16 mm) or greater than one vertebral body while still achieving benefits associated with increased spacing, e.g., reduced complexity. The lead  910  can have all contacts spaced equally (e.g., by up to about two vertebral bodies), or the contacts can have different spacings, as described above. Two or more first contacts C 1  can apply modulation at one vertebral level (e.g., T 9 ) while two or more additional first contacts C 1  can provide modulation at the same or a different frequency at a different vertebral level (e.g., T 10 ). 
     In some cases, it may be desirable to adjust the distance between the inferior contacts C 1  and the superior contacts C 2 . For example, the lead  910  can have a coil arrangement (like a telephone cord) or other length-adjusting feature that allows the practitioner to selectively vary the distance between the sets of contacts. In a particular aspect of this arrangement, the coiled portion of the lead can be located between the first contacts C 1  and the second contacts C 2 . For example, in an embodiment shown in  FIG. 10A , the lead  910  can include a proximal portion  910   a  carrying the first contacts C 1 , a distal portion  910   c  carrying the second contacts C 2 , and an intermediate portion  910   b  having a pre-shaped, variable-length strain relief feature, for example, a sinusoidally-shaped or a helically-shaped feature. The lead  910  also includes a stylet channel or lumen  915  extending through the lead  910  from the proximal portion  910   a  to the distal portion  910   c.    
     Referring next to  FIG. 10B , the practitioner inserts a stylet  916  into the stylet lumen  915 , which straightens the lead  910  for implantation. The practitioner then inserts the lead  910  into the patient, via the stylet  916 , until the distal portion  910   c  and the associated second contacts C 2  are at the desired location. The practitioner then secures the distal portion  910   c  relative to the patient with a distal lead device  917   c.  The distal lead device  917   c  can include any of a variety of suitable remotely deployable structures for securing the lead, including, but not limited to an expandable balloon. 
     Referring next to  FIG. 10C , the practitioner can partially or completely remove the stylet  916  and allow the properties of the lead  910  (e.g., the natural tendency of the intermediate portion  910   b  to assume its initial shape) to draw the proximal portion  910   a  toward the distal portion  910   c.  When the proximal portion  910   a  has the desired spacing relative to the distal portion  910   c,  the practitioner can secure the proximal portion  910   a  relative to the patient with a proximal lead device  917   a  (e.g., a suture or other lead anchor). In this manner, the practitioner can select an appropriate spacing between the first contacts C 1  at the proximal portion  910   a  and the second contacts C 2  at distal portion  910   c  that provides effective treatment at multiple patient locations along the spine. 
       FIG. 11A  is an enlarged view of the proximal portion  910   a  of the lead  910 , illustrating an internal arrangement in accordance with a particular embodiment of the disclosure.  FIG. 11B  is a cross-sectional view of the lead  910  taken substantially along line  11 B- 11 B of  FIG. 11A . Referring now to  FIG. 11B , the lead  910  can include multiple conductors  921  arranged within an outer insulation element  918 , for example, a plastic sleeve. In a particular embodiment, the conductors  921  can include a central conductor  921 a. In another embodiment, the central conductor  921   a  can be eliminated and replaced with the stylet lumen  915  described above. In any of these embodiments, each individual conductor  921  can include multiple conductor strands  919  (e.g., a multifilar arrangement) surrounded by an individual conductor insulation element  920 . During manufacture, selected portions of the outer insulation  918  and the individual conductor insulation elements  920  can be removed, thus exposing individual conductors  921  at selected positions along the length of the lead  910 . These exposed portions can themselves function as contacts, and accordingly can provide modulation to the patient. In another embodiment, ring (or cylinder) contacts are attached to the exposed portions, e.g., by crimping or welding. The manufacturer can customize the lead  910  by spacing the removed sections of the outer insulation element  918  and the conductor insulation elements  920  in a particular manner. For example, the manufacturer can use a stencil or other arrangement to guide the removal process, which can include, but is not limited to, an ablative process. This arrangement allows the same overall configuration of the lead  910  to be used for a variety of applications and patients without major changes. In another aspect of this embodiment, each of the conductors  921  can extend parallel to the others along the major axis of the lead  910  within the outer insulation  918 , as opposed to a braided or coiled arrangement. In addition, each of the conductor strands  919  of an individual conductor element  920  can extend parallel to its neighbors, also without spiraling. It is expected that these features, alone or in combination, will increase the flexibility of the overall lead  910 , allowing it to be inserted with a greater level of versatility and/or into a greater variety of patient anatomies then conventional leads. 
       FIG. 11C  is a partially schematic, enlarged illustration of the proximal portion  910   a  shown in  FIG. 11A . One expected advantage of the multifilar cable described above with reference to  FIG. 11B  is that the impedance of each of the conductors  921  can be reduced when compared to conventional coil conductors. As a result, the diameter of the conductors  921  can be reduced and the overall diameter of the lead  910  can also be reduced. One result of advantageously reducing the lead diameter is that the contacts C 1  may have a greater length in order to provide the required surface area needed for effective modulation. If the contacts C 1  are formed from exposed portions of the conductors  921 , this is not expected to present an issue. If the contacts C 1  are ring or cylindrical contacts, then in particular embodiments, the length of the contact may become so great that it inhibits the practitioner&#39;s ability to readily maneuver the lead  910  during patient insertion. One approach to addressing this potential issue is to divide a particular contact C 1  into multiple sub-contacts, shown in  FIG. 11C  as six sub-contacts C 1   a -C 1   f.  In this embodiment, each of the individual sub-contacts C 1   a -C 1   f  can be connected to the same conductor  921  shown in  FIG. 11B . Accordingly, the group of sub-contacts connected to a given conductor  921  can operate essentially as one long contact, without inhibiting the flexibility of the lead  910 . 
     As noted above, one feature of the foregoing arrangements is that they can be easy to design and manufacture. For example, the manufacturer can use different stencils to provide different contact spacings, depending upon specific patient applications. In addition to or in lieu of the foregoing effect, the foregoing arrangement can provide for greater maneuverability and facilitate the implantation process by eliminating ring electrodes and/or other rigid contacts, or dividing the contacts into subcontacts. In other embodiments, other arrangements can be used to provide contact flexibility. For example, the contacts can be formed from a conductive silicone, e.g., silicone impregnated with a suitable loading of conductive material, such as platinum, iridium or another noble metal. 
     Yet another feature of an embodiment of the lead shown in  FIG. 9  is that a patient can receive effective therapy with just a single bipolar pair of active contacts. If more than one pair of contacts is active, each pair of contacts can receive the identical waveform, so that active contacts can be shorted to each other. In another embodiment, the implanted pulse generator (not visible in  FIG. 9 ) can serve as a return electrode. For example, the pulse generator can include a housing that serves as the return electrode, or the pulse generator can otherwise carry a return electrode that has a fixed position relative to the pulse generator. Accordingly, the modulation provided by the active contacts can be unipolar modulation, as opposed to the more typical bipolar stimulation associated with standard SCS treatments. 
     6.0 Representative Programmer Configurations 
     The robust characteristics of the presently disclosed therapy techniques may enable other aspects of the overall system described above with reference to  FIGS. 1A-B  to be simplified. For example, the patient remote and the physician programmer can be simplified significantly because the need to change signal delivery parameters can be reduced significantly or eliminated entirely. In particular, it is expected that in certain embodiments, once the lead is implanted, the patient can receive effective therapy while assuming a wide range of positions and engaging in a wide range of activities, without having to change the signal amplitude or other signal delivery parameters. As a result, the patient remote need not include any programming functions, but can instead include a simple on/off function (e.g., an on/off button or switch). The patient remote may also include an indicator (e.g., a light) that identifies when the pulse generator is active. This feature may be particularly useful in connection with the presently disclosed therapies because the patient will typically not feel a paresthesia, unless the system is configured and programmed to deliberately produce paresthesia in addition to the therapy signal. In particular embodiments, the physician programmer can be simplified in a similar manner, though in some cases, it may be desirable to maintain at least some level of programming ability at the physician programmer. Such a capability can allow the physician to select different contacts and/or other signal delivery parameters in the rare instances when the lead migrates or when the patient undergoes physiological changes (e.g., scarring) or lifestyle changes (e.g., new activities) that are so significant they require a change in the active contact(s) and/or other signal delivery parameters.  FIGS. 12A-13H  illustrate representative devices and associated methodologies that reflect one or more of the foregoing features in accordance with particular embodiments of the present disclosure. 
       FIG. 12A  is a partially schematic illustration of a remote control device  1200  (e.g., a patient remote) configured in accordance with an embodiment of the disclosure. The patient remote  1200  can be operated by a patient during the course of therapy, e.g., generally as described above with reference to  FIG. 1A . In a particular embodiment shown in  FIG. 12A , the patient remote  1200  includes a wireless transmitter and only a single input device  1201 . The wireless transmitter establishes a communication link  1205  with an implanted pulse generator (e.g., the pulse generator  101  described above with reference to  FIG. 1A ). A link indicator  1203  indicates whether the patient remote  1200  has established the communication link  1205  with the pulse generator, which in turn enables directive signals provided by the input device  1201  to be transmitted to the pulse generator. 
     In a further particular aspect of this embodiment, the single input device  1201  controls only two states of the associated implanted pulse generator. For example, the input device  1201  can control only whether the pulse generator is “on” (e.g., enabled to provide modulating signals to the patient) or “off” (e.g., disabled from providing modulating signals to the patient). In yet a further particular embodiment, the single input device  1201  can be limited so as to (a) allow the pulse generator to be on so long as the input device  1201  is not activated, and to (b) shut the pulse generator down if the input device  1201  is activated. In this embodiment, the practitioner initially activates the pulse generator, and the patient can shut it off (e.g., under specific conditions, such as an emergency). The practitioner&#39;s input is then required to re-activate the pulse generator. A power indicator  1202  (e.g., an LED or other visual indicator, audio indicator, or other type of indicator) identifies whether the input device  1201  has placed the associated pulse generator in an on state or an off state. This feedback feature may be of particular value to a patient receiving non-paresthesia-inducing therapy, because the patient may not immediately sense such therapy otherwise. The input device  1201  can include a push button, touch pad, or other suitable component. In a particular embodiment, the input device  1201  can send a different directive signal to the pulse generator, depending upon whether the input signal is intended to turn the pulse generator on or off. In another embodiment, the input device  1201  can send the same signal to the pulse generator, and the pulse generator simply toggles between an on state and an off state with each new input received via the input device  1201 . In any of these embodiments, the patient remote  1201  can be sized and shaped to be easily held and operated with one hand. 
       FIG. 12B  is a partially schematic illustration of a patient remote  1200  configured in accordance with another embodiment of the disclosure. In this embodiment, the input device  1201  can direct the associated implanted pulse generator to be in one of at most two or possibly more (e.g., three) alternate states. For example, the implanted pulse generator can be configured to deliver signals to the patient in accordance with a most two different signal delivery programs. By activating the input device  1201 , the patient can toggle between a first program and a second program. Each program can have associated with it a corresponding program indicator  1204   a,    1204   b,  and the active program can be indicated by a different appearance of the corresponding indicator. For example, the program indicators  1204   a,    1204   b  can include lights, LEDs or other devices that are active (e.g., illuminated) when the associated program is active, and inactive when the associated program is inactive. In representative embodiments, the two programs can be sleep/awake programs or normally active patient/very active patient programs. In these and other embodiments, the difference between programs can be limited to current amplitude differences (as opposed to other differences, e.g., frequency differences and active contact differences). The patient remote  1200  can also be used to control whether the implanted pulse generator is on or off, with an off state indicated when neither program indicator  1204   a,    1204   b  is active. As discussed above with reference to  FIG. 12A , the patient remote  1200  can issue different directive signals depending upon the desired target state at the implanted pulse generator, or the patient remote  1200  can direct the same signal to the implanted pulse generator, and the implanted pulse generator can sequentially step through the states (e.g., off, program  1 , program  2 , off, etc.) with the arrival of each new directive signal. 
     One feature of the embodiments described above with reference to  FIGS. 12A and 12B  is that the patient remote  1200  can include a limited function input device  1201 , e.g., an input device that is prohibited from carrying out certain actions. In particular, the patient remote  1200  shown in  FIG. 12A  can only change the state of the corresponding implanted pulse generator between an on state and an off state, and the patient remote  1200  shown in  FIG. 12B  can only change the state of the corresponding implanted pulse generator between an off state, a first program, and a second program. Notably, the patient remote  1200  shown in  FIG. 12A  does not have control over the amplitude, frequency, and/or other signal delivery parameters in accordance with which the modulating signal is provided to the patient. The patient remote  1200  shown in  FIG. 12B  has limited control over these features, in that the different programs will typically include different signal delivery parameters. However, the patient remote  1200  does not have capability to control each of the signal delivery parameters independently, or outside the confines of the selectable programs set by the practitioner. 
     One advantage of the foregoing arrangement is that it can simplify the patient&#39;s life by reducing the patient&#39;s involvement with controlling the therapy provided by the electrical signals. In this embodiment, reduced control is not a disadvantage for the patient, but instead capitalizes on the robust nature of the therapy described above. For example, the robust nature of the therapy can reduce or eliminate the need for the patient to control signal amplitude, delivery location and/or other parameters without impacting the efficacy of the therapy. Another advantage associated with the foregoing features is that the practitioner can more easily track the therapy delivered to the patient. For example, the patient remote  1200  can store information identifying when the implanted pulse generator is activated and, if the patient has enabled multiple programs, which program is active. With fewer variables to control, the data are expected to be simpler to understand and easier to make use of. 
     In other embodiments, the overall system can operate in other manners to achieve at least some of the foregoing results. For example, the pulse generator can be configured to respond only to certain requests, or not respond to particular requests from a patient remote. In a particular example, the pulse generator can be configured to not respond to requests from a patient remote for a change in amplitude, program, or active contact selection. One application for this approach is that it allows existing patient remotes to be used in the limited-function manner described above. 
       FIGS. 13A-13H  illustrate devices and associated methodologies that the practitioner can use to control the therapy provided to the patient. In general, these devices and methodologies allow the practitioner more control over the therapy than is typically granted to the patient. These features and methodologies can be implemented on a device that is temporarily hardwired directly to the lead (e.g., in the manner of the external programmer  105  described above with reference to  FIG. 1A ) or via a wireless link to an implanted pulse generator (e.g., in the manner of the physician&#39;s programmer  111 , also described above with reference to  FIG. 1A ). The patient remote  1200  and the practitioner&#39;s controller can each include different security keys, codes, or authorization arrangements that are automatically transmitted to and interpreted by the controlled device (e.g., the implanted pulse generator). Accordingly, the controlled device can be controlled by either the patient remote (e.g., in a first mode) or the practitioner&#39;s controller (e.g., in a second mode) as appropriate. 
       FIG. 13A  schematically illustrates a practitioner&#39;s controller  1310  having a display medium  1312  (e.g., an LCD, LED array, or other suitable medium) and one or more input devices  1311  that are used to input information displayed at the display medium  1312 . The practitioner&#39;s controller  1310  can also include an internal memory  1313  and processor  1314  (and/or other computer/machine readable media) that store and execute programs and/or instructions associated with establishing and presenting signal delivery parameters at the display medium  1312 . If the controller  1310  is connected directly to a lead or other signal delivery device, then it also includes an internal pulse generator for generating the modulation signal. If the controller  1310  is wirelessly connected to an implanted pulse generator, then it can control the manner in which signals are generated by the implanted pulse generator. Aspects of displays presented at the display medium  1312  are described in further detail below with reference to  FIGS. 13B-13H . 
       FIG. 13B  illustrates a representation of a display  1320  that may be presented at the display medium  1312  shown in  FIG. 13A . The display  1320  can include a two-dimensional, graphical layout, with a vertical axial scale  1321  identifying axial locations along the patient&#39;s spine (e.g., from T 8  to T 12 ) and a lateral amplitude scale  1322  identifying the current amplitude (e.g., in mA) with which a therapeutic signal is delivered to the patient. The display  1320  also includes a therapy location identifier  1326  indicating where along the axial scale  1321  the modulation signal is applied, and an available amplitude window  1323  that indicates the range of current amplitudes the practitioner has access to. An amplitude identifier  1324  indicates the present amplitude level. Accordingly, the practitioner can move the therapy location identifier  1326  up and down along the axial scale  1321  (e.g., using a drag and drop routine or other suitable arrangement), and can adjust the amplitude of the signal by moving the amplitude identifier  1324  back and forth (e.g., also using a drag and drop or other suitable arrangement). 
     The display  1320  also includes one or more pain score identifiers  1327  (three of which are shown in  FIG. 13B  as first, second, and third pain score identifiers  1327   a,    1327   b,    1327   c,  respectively). The pain score identifiers  1327  can identify numerical VAS scores (or other suitable index values) as a function of amplitude and axial location along the spine. The scores can be for the particular patient presently receiving therapeutic modulation, or for other relevant patients or patient populations. For example, the pain score identifiers  1327  can reflect data for a patient population having symptoms or indications similar to those experienced by the present patient. Accordingly, the practitioner can view historical pain scores for a representative patient or patient population in the same manner and on the same display as are displayed the location and amplitude of the patient presently receiving therapeutic modulation. This can aid the practitioner in selecting an appropriate axial location and amplitude for the present patient. For example, the practitioner can locate the amplitude and axial location of the modulation at or proximate to the pain score identifier  1327  with the lowest value (e.g., pain score identifier  1327   c ). An advantage of this arrangement is that it presents historical information and adjustable patient parameters together in an easy-to-view and easy-to-manipulate format. 
       FIG. 13B  illustrates a single lead extending from about vertebral level T 8  to about vertebral level T 12 . In other embodiments, the patient may have multiple leads implanted along the spine. For example, referring now to  FIG. 13C , the display  1320  presents a first lead identifier  1325   a  corresponding to a first lead and a second, inferiorly located lead identifier  1325   b  corresponding to a second lead. Using the lead identifiers  1325   a,    1325   b  as guides, the practitioner can manipulate the location and amplitude of the modulation provided to the patient, in the manner generally described above with reference to  FIG. 13B . In the region where the two leads overlap, the practitioner can drag or otherwise move the therapy location identifier  1326  laterally from one lead to another to select the lead that will apply the modulation signal. If the practitioner drags the therapy location identifier  1326  above or below the axial extent of a particular lead, the program can automatically shift the therapy location identifier to  1326  to the adjacent lead, assuming the adjacent lead has the appropriate axial extent. In any of these embodiments, the program can automatically select the contacts on the lead that are closest to the therapy location identifier  1326 . Further aspects of this feature are described in greater detail below with reference to  FIGS. 13D and 13E . 
     Referring now to  FIG. 13D , the detailed display  1320  described above with reference to  FIGS. 13B and 13C  has been simplified and made part of an overall display  1320   a.  The overall display  1320   a  can include a status identifier  1330  (e.g., identifying the patient, device, and battery state), a program options indicator  1328  (e.g., identifying available programs), a lead position summary  1329 , and a signal delivery parameter identifier  1333 . The overall display  1320   a  can also include contact identifiers  1331  for each implanted lead. In the embodiment shown in  FIG. 13D , the patient has two implanted leads and accordingly two corresponding sets of contact identifiers  1331   a,    1331   b.  Next to each contact identifier set  1331   a,    1331   b  is a corresponding program identifier  1332   a,    1332   b  which identifies an available program (e.g., program “P 1 ”). The therapy location indicator  1326  appears along the program identifier  1332   a  to indicate the location at which the therapy is provided in association with that program. In the particular embodiment shown in  FIG. 13D , the patient receives therapy centered approximately at vertebral location T 9 . 5 , via the left/superior lead and no therapy via the right/inferior lead. 
     As indicated above, the program can automatically select appropriate signal delivery contacts depending upon the location at which the practitioner places the therapy location identifier  1326 . For example, as shown in  FIG. 13D , the practitioner has moved the therapy location identifier  1326  to the illustrated location, and the program has automatically selected contacts “ 3 ” and “ 5 ” to deliver modulation over an area extending at least between these contacts. One feature of this arrangement is that the practitioner need not select which contacts are active. Instead, the practitioner can select the desired vertebral location (e.g., based on the pain score indicators  1327 ) and allow the program to select the appropriate contacts. Another feature of this arrangement is that the practitioner need not select which of the active contacts is anodic or cathodic. As used herein, the cathodic contact refers to the contact that receives a negative or polarizing pulse at the outset of a pulse train in accordance with which the modulation is provided. As discussed above, it is believed that the presently disclosed therapy is insensitive or relatively insensitive to which contact in a bipolar pair of contacts is anodic or cathodic. Accordingly, the practitioner need not make this selection, which simplifies the practitioner&#39;s task of establishing program parameters for the patient. In particular, the practitioner controller  1310  can be prohibited from accepting user inputs for cathode/anode selection. Instead, the program executed by the practitioner&#39;s controller  1310  (or by the implanted pulse generator with which it communicates) can automatically select which contact is anodic and which is cathodic without user input, in accordance with any of a variety suitable algorithms. For example, the program can select the superior contact to be cathodic, and the inferior contact to be anodic. In other embodiments, this relationship can be reversed. 
     In any of the foregoing embodiments described above with reference to  FIG. 13D , the therapy location identifier  1326  can be highlighted or otherwise differentiated when the practitioner has active control over the signal delivery parameters associated with the therapy provided at that location. For example, as shown in  FIG. 13D , the therapy location identifier  1326  is brightly displayed, indicating to the practitioner that the associated signal delivery parameters may be controlled by manipulating the signal delivery parameter identifiers  1333 . These identifiers can include pulse identifiers  1335 , and amplitude identifiers  1334 . The amplitude identifiers  1334  can include a minimum amplitude  1336 , a maximum amplitude  1337 , a starting amplitude  1338 , an amplitude step identifier  1339 , and a present amplitude identifier  1340 . The practitioner can select the amplitude step and then adjust the amplitude between the minimum value and the maximum value, with the present value indicated by the present amplitude identifier  1340 . 
     One feature of the arrangement shown in  FIG. 13D  is that the minimum amplitude  1336  can be a non-zero value set by the practitioner or by the manufacturer. This is unlike typical SCS controllers, which generally allow the practitioner or the patient to adjust the amplitude down to zero. The present therapy however, often does not provide an immediately detectable sensation (e.g., paresthesia) that indicates to the patient that the therapy is operating. Accordingly, establishing a minimum amplitude level can prevent the patient or the practitioner from inadvertently selecting an amplitude that is too low to provide therapy, which may not be detected by the patient for some time. In a particular embodiment shown in  FIG. 13D , the minimum amplitude is set at 2 mA. As discussed above, the minimum amplitude may have lower values (e.g., 1 mA or 0.5 mA) depending upon factors including patient-specific factors and/or indication-specific factors. 
       FIG. 13E  is a partially schematic illustration of the display  1320   a,  showing information relating to multiple leads, multiple programs, and multiple therapy location indicators. In particular,  FIG. 13E  illustrates the first contact identifier set  1331   a  associated with a first lead, and the second contact identifier set  1331   b  associated with a second lead. Two available programs (“P 1 ” and “P 2 ”) are indicated for each lead by program identifiers  1332   a   1 ,  1332   a   2  for the first lead, and program identifiers  1332   b   1 ,  1332   b   2  for the second lead. In this particular arrangement, the practitioner has selected modulation locations for both programs  1  and  2  at the first lead (as shown by first and second therapy location indicators  1326   a   1 ,  1326   a   2 ), and for only program  2  (as shown by a third therapy location indicator  1326 b 2 ) at the second lead. The signal delivery parameters presented by the signal delivery parameter identifiers  1333  are associated with the therapy provided at the first lead under program P 2 , as identified by the second location indicator  1326 a 2 , which is highlighted in  FIG. 13E . The other selected therapy location indicators  1326 a 1  and  1326 b 2  are shown in gray scale. Accordingly, the practitioner can readily identify which program and therapy location the signal delivery parameter identifiers  1333  correspond to. 
     Another feature shown in  FIG. 13E  is that the practitioner can, if desired, override the default contact selection procedure carried out by the program. For example, the program automatically selected the therapy areas to extend over three contacts for programs P 1  and P 2  at the first lead. In a particular embodiment, this can be the default selection process. For program P 2  at the second lead, the practitioner has changed the length of the therapy location identifier  1326   b   2  so that it extends over four contacts (contacts  11 - 14 ). In other embodiments, the practitioner can select the therapy area to extend over other lengths, shorter or longer than those shown in  FIG. 3E . In general, the program can select the two contacts positioned at the superior and inferior extremes of the therapy area to be the active contacts. 
     One aspect of several of the embodiments described above is that the program and associated system can automatically select the active contacts based on an input (e.g., from the practitioner) corresponding to the vertebral level at which the therapy is to be applied. In further embodiments, the program can automate still further functions, in addition to or in lieu of the foregoing functions. For example, the program can automatically select contact locations and/or other signal delivery parameters based on an input corresponding to a patient indication, e.g., a single input corresponding only to a patient indication. Other inputs can include the features of the signal delivery device that is or is to be implanted, e.g., the type (lead or paddle), model number, manufacturer and/or other features. 
       FIG. 13F  is a partially schematic illustration of a display  1320   b  configured in accordance with another embodiment of the present disclosure. In this particular embodiment, the display  1320   b  presents first and second lead identifiers  1325   a,    1325   b,  each of which includes corresponding first contact identifiers  1331   a  and second contact identifiers  1331   b.  Each contact identifier can in turn include an impedance level associated with that contact. The practitioner can activate an impedance check button  1342  to initiate an impedance check, which updates the values indicated by the contact identifiers  1331   a,    1331   b.  On the basis of the impedance values associated with each contact, the program can automatically select particular contacts having an impedance value within an appropriate, pre-established range, that are located near a target vertebral level, and/or can reject one or more contacts having an impedance value that is outside the pre-established range. 
     The practitioner can adjust the relative location between the leads and the illustrated vertebral levels to match or closely correspond to the actual relative locations of the leads in the patient&#39;s body, using any of a number of suitable methods. For example, the practitioner can “drag and drop” one of the lead identifiers  1325   a,    1325   b  so that that it is properly aligned with the adjacent vertebral level identifiers  1340 . If the patient&#39;s vertebral levels do not have the axial dimensions illustrated at the display  1320   b,  the practitioner can alter these dimensions. For example, the practitioner can drag and drop individual boundaries  1341  between adjacent vertebral level identifiers  1340  to adjust the axial extent of each vertebral level identifier  1340 . In addition to or in lieu of the foregoing, the practitioner can scale all the vertebral levels simultaneously with a single control. The practitioner can move the lead identifier  1325   a,    1325   b  and/or manipulate the boundaries  1341  between vertebrae based on viewing an image of the implanted lead(s) via an x-ray or other imaging protocol. 
     Once the practitioner has properly located one of the lead identifiers  1325   a,    1325   b  relative to the adjacent vertebral level identifiers  1340 , the practitioner can request that the program automatically adjust the location of the other lead identifier relative to the first by activating an “auto align button”  1343 . The program can automatically align one lead identifier relative to the other based upon measured data, for example, the impedance data associated with contacts on one or both leads. 
     The display  1320   b  can also include a preset window  1344 . When the practitioner clicks on the preset window  1344 , a preset menu  1345  appears and lists multiple preset identifiers  1346 . In a particular embodiment, each preset identifier  1346  can be labeled with a patient indication that may be addressed by one or more of the contacts located at the vertebral levels indicated by the vertebral level identifiers  1340 . For example, with the contacts positioned between T 8  and T 12 , the preset identifiers  1346  may correspond to “low back pain,” “leg pain,” and/or other patient indications that may be treated by activating contacts at these vertebral levels. In other embodiments, for example, when the leads are located at cervical vertebral levels, a different list of preset identifiers  1346  appears when the practitioner activates the preset window  1344 . 
       FIG. 13G  illustrates the display  1320   b  after the practitioner has selected one of the preset identifiers  1346  shown in  FIG. 13F . In this particular embodiment, the practitioner has selected the “Nevro Factory Default” preset identifier, which can correspond to an indication of low back pain, and can have associated descriptive text (not shown) and/or other indicia, such as an icon or audible tone, to further identify the preset as suitable for treating low back pain. In response, the program presents available modulation program identifiers  1350 . Each modulation program can include a vertebral level (or location within a vertebral level) along with associated signal delivery characteristics, for example, frequency, pulse width and amplitude. The overall program and/or an individual modulation program can then automatically identify and select the contacts closest to that vertebral level. The practitioner has the option of modifying at least some of these pre-set parameters, e.g., the maximum and minimum amplitudes associated with the particular modulation program. The practitioner can select one of the available modulation program identifiers  1350  resulting in a selected modulation program identifier  1348  which is highlighted or presented in a different color, or otherwise indicated to be distinct from the remaining available modulation program identifiers  1350 . The selected program is also presented at a program selection window  1349 . In addition, the display  1320   b  can identify the active contacts associated with the selected modulation program via active contact identifiers  1347 . In this particular embodiment, the active contact identifier  1347  includes presenting the active contacts in a different color and/or presenting a “plus” or “minus” sign within the active contact identifier  1347 . As discussed above, while the contacts may be indicated as positive or negative, the practitioner need not (and may not) have control over whether an individual contact is considered anodic or cathodic. 
     The active contacts can automatically be selected by the overall program depending on which modulation program the practitioner selects via the program selection window  1349 . For example, if the user selects a particular modulation program intended for treating low back pain, that modulation program can have a predetermined correlation between active contacts and a vertebral level. The modulation program can have a predetermined requirement that the fourth contact down from the top of the lead be at approximately the middle of vertebral level T 9 , and the other contact of an active contact pair should be the next adjacent contact closest to the middle of vertebral level T 9 . If one or more of the contacts are unavailable (e.g., due to out-of-range impedance or an impedance that differs from a target value) the overall program and/or an individual modulation program can automatically select the pair of contacts closest to the target level. 
     The overall program can automatically take advantage of information that indicates a successful modulation location and can generate backup parameters which include, but are not limited to, backup contact locations. The backup locations can be automatically implemented, e.g., if the lead were to move. For example, the program can automatically track how long the patient uses different modulation programs and, based upon the assumption that the patient will use successful modulation programs more often than unsuccessful modulation programs, can rank the modulation programs. If the contacts associated with a particularly successful modulation program become unavailable (e.g., due to the lead shifting or an impedance change in the lead), the system can automatically select the next-best set of modulation parameters. In another embodiment, the patient or a practitioner can manually bracket the vertebral levels over which the system can select alternative sets of modulation parameters. In still further embodiments, the patient can directly input data that identifies which modulation programs are most desirable. 
       FIG. 13H  is a schematic block diagram illustrating a representative example of a technique for automatically selecting signal delivery parameters based, e.g., solely based, on the patient indication and the location of a signal delivery device implanted in the patient. The overall process  1300  can include implanting a signal delivery device (process portion  1301 ). The signal delivery device can include any of the foregoing signal delivery devices described above, including but not limited to an elongated spinal cord lead. Process portion  1302  includes establishing a positional relationship between the signal delivery device and an anatomic feature of the patient in which the signal delivery device is implanted. For example, process portion  1302  can include establishing a positional relationship between a marker on the signal delivery device and/or an electrical contact on the signal delivery device, relative to one or more of the patient&#39;s vertebrae. In particular embodiments, this process can be carried out with varying degrees of practitioner involvement. In one example, the practitioner can use fluoroscopy, ultrasound, and/or other techniques to establish the correlation between a single contact and a vertebral level. In other embodiments, paresthesia testing can be used to correlate the location of the signal delivery device with the patient&#39;s anatomical features. For example, low frequency conventional SCS signals, which generate paresthesia, can be used for this process, even if higher frequency signals are used during therapy. Referring now to  FIG. 13F , the practitioner can then move the lead identifiers  1325   a,    1325   b  and/or manipulate the vertebral boundaries  1341  to properly align the contacts with corresponding vertebral levels. The alignment can include an axial component and/or a medial component. 
     In still further embodiments, the active electrode selection process can be further automated and/or can be performed with additional precision. For example, the practitioner can use a touch-screen or other graphical user interface (GUI) that presents one or more fluoroscopy or other image(s), and can touch the screen to correlate particular electrodes or other markers on the signal delivery device with one or more vertebrae. In still further embodiments, the system can use image recognition techniques to automatically identify markers on the electrode and/or automatically identify particular vertebral levels. Based on this information, the system can automatically identify the positional relationship between one or more of the electrodes and one or more corresponding vertebrae. The practitioner can verify or confirm the positional relationship established automatically by the program, based on the practitioner&#39;s view of the same image or a different image (or, in complex cases, several images, e.g., obtained in different planes), and/or based on the practitioner&#39;s background knowledge or other data. 
     Process portion  1303  includes receiving an input corresponding to a patient indication. For example, the practitioner can be presented with a menu, list, and/or other display from which the practitioner selects one or more patient indications, as discussed above with reference to  FIGS. 13F-13G . The patient indications can include, for example, leg pain, low back pain, mid-back pain, upper back pain, total body pain, cervical pain, cephalalgia or any of a variety of combinations of the foregoing and/or other representative pain indications. The database or other repository of the indications can be updated periodically as treatments for new indications are developed. 
     In process portion  1304 , the program can automatically select one or more signal delivery parameters based at least in part on the positional relationship established in process portion  1302  and the patient indication identified in process portion  1303 . For example, the process can include automatically identifying which electrodes should be activated based on where the electrodes are located relative to the patient&#39;s vertebrae, and which one or more indications the patient presents with. To identify the electrodes, the program can access one or more databases containing information (e.g., aggregated data obtained from similarly treated patients) which establish correlations between electrode location and patient indication. The process can include selecting one or more electrodes (e.g., two electrodes) at or closest to the vertebral level best correlated with successful treatment of the patient indication. The database(s) can also include other parameters, for example, signal delivery frequency, pulse width, interpulse interval, and/or amplitude (e.g., current amplitude and/or voltage amplitude). Process portion  1304  can include selecting values for any of these parameters, in addition to or in lieu of selecting which electrodes are active. The manner in which the system selects the patient parameters can include selecting from a list of pre-established modulation programs, or using a table-lookup function, a mathematical expression, and/or any of a wide variety of suitable correlation techniques known to those of ordinary skill in the relevant art. 
     The data included in the database or other repository of information can initially be obtained from clinical results. For example, practitioners with experience delivering high frequency signals to patients with back pain can contribute data to the database that identifies the vertebral level and other signal delivery parameters that produced the most efficacious patient results. Data for other indications and/or combinations of indications may be used to populate the database in a similar manner. As practitioners gain more experience with particular indications, the database can be updated periodically to reflect the accumulated additional knowledge gained by these practitioners. Similarly, as practitioners develop therapies for new patience indications, the database can be updated to reflect up-to-date experience associated with such indications. 
     The foregoing technique can be used to establish signal delivery parameters (which include electrode location and the attributes of the signal itself) at the outset of a trial period and/or at the outset of a permanent or long-term implant period. The foregoing process can also be used to establish correlations between trial and permanent therapy parameters, and/or to update the parameters post-implant. For example, during a representative trial, a percutaneous trial lead is partially implanted in the patient and connected to an external trial stimulator. After the efficacy of the therapy is demonstrated during the trial period, the trial lead is typically removed and replaced with a permanent or long-term implanted lead and an implanted pulse generator, as described above with reference to  FIGS. 1A-1B . In at least some instances, the permanent lead is not implanted in exactly the same location as was the trial lead. The process described above with reference to  FIG. 13F  can be used to automatically establish an offset (e.g., distance and direction) between electrodes on the trial lead and electrodes on the permanent lead, and, if necessary, update the signal delivery parameters (e.g., the active electrodes) based on that offset distance. For example, if during the trial, one contact was aligned at vertebral level T 9 , and after the permanent lead was implanted, another (different) contact is aligned at vertebral level T 9 , the system can automatically shift the active electrode from the one contact to the other contact. 
     In still further embodiments, the process can automatically account for lead migration. For example, the patient can periodically undergo an x-ray to determine if the lead or other signal delivery device has shifted. The system can receive this information and automatically update signal delivery parameters (e.g., which electrodes are active) based on any shifts that the lead may have undergone. In still further embodiments, the system can automate other aspects of the implantation and/or therapy processes. For example, the system can respond to a user input specifying one or more patient indications by providing one or more suggested locations at which the lead or other signal delivery device should be positioned. 
     Particular embodiments of the foregoing processes can produce one or more of several advantages. For example, by automating these processes, the amount of time required for accurately selecting signal delivery parameters can be reduced, thereby increasing the number of patients who can be treated in a given period of time. In addition, the automated techniques can take advantage of large quantities of patient data to establish signal delivery parameters for a particular patient, in a manner that would be cumbersome, unwieldy, and/or very time consuming if it were performed by an individual practitioner. 
     7.0 Representative Modulation Locations and Indications 
     Many of the embodiments described above were described in the context of treating chronic, neuropathic low back pain with modulation signals applied to the lower thoracic vertebrae (T 9 -T 12 ). In other embodiments, modulation signals having parameters (e.g., frequency, pulse width, amplitude, and/or duty cycle) generally similar to those described above can be applied to other patient locations to address other indications. For example, while the foregoing methodologies included applying modulation at lateral locations ranging from the spinal cord midline to the DREZ, in other embodiments, the modulation may be applied to the foramen region, laterally outward from the DREZ. In other embodiments, the modulation may be applied to other spinal levels of the patient. For example, modulation may be applied to the sacral region and more particularly, the “horse tail” region at which the sacral nerves enter the sacrum. Urinary incontinence and fecal incontinence represent example indications that are expected to be treatable with modulation applied at this location. In other embodiments, the modulation may be applied to other thoracic vertebrae. For example, modulation may be applied to thoracic vertebrae above T 9 . In a particular embodiment, modulation may be applied to the T 3 -T 6  region to treat angina. Modulation can be applied to high thoracic vertebrae to treat pain associated with shingles. Modulation may be applied to the cervical vertebrae to address chronic regional pain syndrome and/or total body pain, and may be used to replace neck surgery. Suitable cervical locations include vertebral levels C 3 -C 7 , inclusive. In other embodiments, modulation may be applied to the occipital nerves, for example, to address migraine headaches. 
     As described above, modulation in accordance with the foregoing parameters may also be applied to treat acute and/or chronic nociceptive pain. For example, modulation in accordance with these parameters can be used during surgery to supplement and/or replace anesthetics (e.g., a spinal tap). Such applications may be used for tumor removal, knee surgery, and/or other surgical techniques. Similar techniques may be used with an implanted device to address post-operative pain, and can avoid the need for topical lidocaine. In still further embodiments, modulation in accordance with the foregoing parameters can be used to address other peripheral nerves. For example, modulation can be applied directly to peripheral nerves to address phantom limb pain. 
     Additional Embodiments 
     A system in accordance with one embodiment includes an implantable signal generator, a first elongated signal delivery lead coupled to the implantable signal generator and positioned proximate to a patient&#39;s spinal cord, a second elongated signal delivery lead coupled to the implantable signal generator and positioned proximate to the patient&#39;s spinal cord, and a programmer in wireless communication with the implantable signal generator. The programmer can have a computer-readable medium with instructions that, when executed, receive a first input indicating a location of the first lead, and a second input indicating a location of the second lead. The instructions, when executed, and establish a first positional relationship between the first lead and a vertebra of the patient, establish a second positional relationship between the second lead and the vertebra of the patient, and receive a third input identifying a medical indication of the patient. Based at least in part on (a) the first positional relationship, (b) the second positional relationship, and (c) the medical indication, the instructions, when executed, can automatically identify at least one electrode, carried by at least one of the first or second lead, and deliver a pulsed electrical signal to the patient&#39;s spinal cord via the at least one electrode. 
     A system in accordance with another embodiment includes a computer-readable medium having instructions that when executed, receive a first input corresponding to a location of a signal delivery device implanted in a patient, establish a positional relationship between the implanted signal delivery device and an anatomical feature of the patient (e.g., a patient&#39;s vertebrae or disk), and receive a second input corresponding to a medical indication of the patient. Based at least in part on the positional relationship and the indication, the instructions can, when executed, automatically identify a signal delivery parameter in accordance with which a pulsed electrical signal is delivered to the patient via the signal delivery device. 
     The instructions, when executed, can access a database of patient information correlating signal delivery parameters and medical indications for other patients. Automatically identifying the signal delivery parameter can include identifying the signal delivery parameter based at least in part on information contained in the database. 
     A method in accordance with still another embodiment includes receiving a first input indicating a location of a signal delivery device implanted in a patient, relative to at least one of the patient&#39;s vertebrae, establishing a positional relationship between the implanted signal delivery device and the at least one vertebra, and receiving a second input corresponding to a medical indication of the patient. The method can include accessing a database of patient information correlating signal delivery parameters and medical indications for other patients, and based at least in part on the positional relationship, the medical indication, and information contained in the database, automatically identify a signal delivery parameter in accordance with which a pulsed electrical signal is delivered to the patient via the signal delivery device. The signal delivery parameter can include an identity of an electrode to which the pulsed electrical signal is delivered, with the electrode being carried by the signal delivery device. 
     The first input can be provided by a user moving a computer-based image of the lead relative to a computer-based image of the at least one vertebra, e.g., to change an axial length of a computer-based image of a vertebra. 
     The signal delivery parameter can include the identity of a first electrode, and the method can further include identifying a second electrode, e.g., when the circuit containing the first electrode has an impedance that is higher or lower than a target value. 
     In particular embodiments, the location of the signal deliver device may be identified relative to an axial location of the spine, a lateral location of the spine, or both. The relative axial and/or lateral location (e.g., with respect to the midline of the spine) can be used to select system parameters and/or identify electrodes for delivery of the therapy signal. For example, the relative axial position of the electrodes may create a need for increasing/decreasing amplitude in order to deliver the therapy signal through cerebral spinal fluid (CSF) proximate to the location of the electrode. Programmer graphical user interfaces can display relative axial and/or lateral location, real-time or calculated CSF measurements, and other parameter information corresponding to the signal deliver device&#39;s location. 
     Still further embodiments of representative therapies and indications are included in the following U.S. Applications, each of which is incorporated herein by reference: Ser. Nos. 12/765,790; 12/765,747; and 13/607,617. 
     The methods disclosed herein include and encompass, in addition to methods of making and using the disclosed devices and systems, methods of instructing others to make and use the disclosed devices and systems. For example, a method in accordance with a particular embodiment includes receiving a first input corresponding to a location of a signal delivery device implanted in a patient, establishing a positional relationship between the implanted signal delivery device and an anatomical feature of the patient, receiving a second input corresponding to a medical indication of the patient, and, based at least in part on the positional relationship and the indication, automatically identifying a signal delivery parameter in accordance with which a pulsed electrical signal is delivered to the patient via the signal delivery device. Accordingly, any and all methods of use and manufacture disclosed herein also fully disclose and enable corresponding methods of instructing such methods of use and manufacture. Methods of instructing such use and manufacture may take the form of computer-readable-medium-based executable programs or processes. 
     From the foregoing, it will be appreciated that specific embodiments of the disclosure have been described herein for purposes of illustration, but that various modifications may be made without deviating from the disclosure. For example, the specific parameter ranges and indications described above may be different in further embodiments. As described above, the practitioner can avoid the use of certain procedures, (e.g., mapping, trial periods and/or current steering), but in other embodiments, such procedures may be used in particular instances. The lead described above with reference to  FIGS. 9-11C  can have more than two groups of contacts, and/or can have other contact spacings in other embodiments. In some embodiments, as described above, the signal amplitude applied to the patient can be constant. In other embodiments, the amplitude can vary in a preselected manner, e.g., via ramping up/down, and/or cycling among multiple amplitudes. The signal delivery elements can have an epidural location, as discussed above with regard to  FIG. 1B , and in other embodiments, can have an extradural location. In particular embodiments described above, signals having the foregoing characteristics are expected to provide therapeutic benefits for patients having low back pain and/or leg pain, when modulation is applied at vertebral levels from about T 9  to about T 12 . In at least some other embodiments, it is believed that this range can extend from about T 5  to about L 1 . Certain processes may be described in the context of multiple inputs, e.g., first, second, and third inputs to a physician&#39;s controller. These inputs may vary from one embodiment to another. 
     Certain aspects of the disclosure described in the context of particular embodiments may be combined or eliminated in other embodiments. For example, as described above, the trial period, operating room mapping process, and/or external modulator may be eliminated or simplified in particular embodiments. Therapies directed to particular indications may be combined in still further embodiments. Further, while advantages associated with certain embodiments have been described in the context of those embodiments, other embodiments may also exhibit such advantages, and not all embodiments need necessarily exhibit such advantages to fall within the scope of the present disclosure. Accordingly, the present disclosure and associated technology can encompass other embodiments not expressly shown or described herein.