Theoretical Investigation Into Longitudinal Cathodal Field Steering in Spinal Cord Stimulation

Objective. When using spinal cord stimulation (SCS) for chronic pain management, precise longitudinal positioning of the cathode is crucial to generate an electrical field capable of targeting the neural elements involved in pain relief. Presently used methods have a poor spatial resolution and lack postoperative flexibility needed for fine tuning and reprogramming the stimulation field after lead displacement or changes in pain pattern. We describe in this article a new method, “electrical field steering,” to control paresthesia in SCS. The method takes advantage of newer stimulator design and a programming technique allowing for “continuous” adjustment of contact combination while controlling stimulation current for each contact separately. Method. Using computer modeling we examined how stimulation of dorsal column (DC) and dorsal root (DR) fibers was influenced by changing the current ratio of the cathodes of a dual (––) and a guarded dual cathode (+––+) configuration programmed on a percutaneous lead with 9 and 4 mm center‐to‐center contact spacing. Results. A cathodal current ratio could be found for which DC or DR fiber recruitment and thus, most likely, paresthesia coverage was maximized. The DR threshold profiles shifted longitudinally, thus following the shift in the electrical field during steering. The profiles had a constant shape when the contact spacing was small and a varying shape for wider contact separation. Generally, the wider contact separation provided less DC and more DR fiber recruitment. Conclusions. By means of cathodal steering on a longitudinal contact array, the group of excited DC and DR fibers, and thus paresthesia coverage, can be controlled when using SCS. With widely spaced contacts, superposition of the electrical field from each steering contact is limited. To precisely control segmental paresthesia (DR stimulation), a small contact spacing is necessary.     

Spinal Cord Stimulation With Interleaved Pulses: A Randomized,Controlled Trial

Objectives. The development of multicontact electrodes and programmable, implanted pulse generators has increased the therapeutic success of spinal cord stimulation (SCS) by enhancing the ability to capture and maintain pain/paresthesia overlap. This study sought to determine if interleaved stimulation and/or frequency doubling improves pain/paresthesia overlap in patients with failed back surgery syndrome. Methods. Using a patient‐interactive computer system that quantifies SCS performance and presents stimulation settings in randomized, double‐blind fashion, we compared the effect on pain/paresthesia overlap of interleaved stimulation (rapidly interleaved pulse trains using two different contact combinations) vs. standard treatment with a single contact combination, controlling for frequency doubling. Stimulation amplitude (charge per phase, as determined by varying pulse voltage or width) was adjusted to a subjectively comfortable intensity (usage amplitude), which was maintained for all trials in each patient. The number of percutaneous spinal electrodes used (one or two) and the phase angle between interleaved pulses were additional study variables. Results. Multivariate analysis of 266 test results from 15 patients revealed a statistically significant (p ≤ 0.05) association between increased computer‐calculated pain/paresthesia overlap and 1) high‐ and low‐frequency interleaved stimulation using two combinations of contacts and 2) frequency doubling using one combination. We found no significant effect for electrode configuration (single or dual), pulse width matching, or phase angle. Conclusions. The statistically significant advantages we observed for SCS with interleaved stimulation are explained, at least in part, by the effects of frequency doubling. These findings have important implications for the design and adjustment of pulse generators.     

Anterograde Revision of Cervical Spinal Cord Stimulator Paddle Electrode: A Case Report

Objectives: To illustrate a new surgical revision strategy for malfunctioning spinal cord stimulation (SCS) paddle electrodes. Background: SCS is a treatment for chronic neuropathic pain that delivers therapeutic doses of electric current to the dorsal columns resulting in dermatomal paresthesia and pain reduction. Reasons for SCS failure include hardware malfunction or breakage and medical complications. Case Report: A 34‐year‐old woman presented with a two‐year history of intractable pain in the left upper extremity and thoracic region which was previously controlled by SCS. Imaging demonstrated breakage of the cervical electrode wire that had been advanced in the caudal direction from the C1 spinal level. Revision of the broken electrode was performed by hemilaminectomy of C3‐C4 and the replacement electrode was advanced in the cephalad direction. Results: Ideal and exact paresthesia pattern was confirmed intraoperatively and the patient maintained successful pain reduction at five‐year follow‐up. Conclusion: Advancing SCS electrodes into the upper cervical spine in the cephalad direction, using the previously formed scar capsule, offers an alternate strategy for revision of malfunctioning SCS paddle electrodes.     

Lumbar and Sacral Nerve Root Stimulation (NRS) in the Treatment of Chronic Pain: A Novel Anatomic Approach and Neuro Stimulation Technique

Objective. The conventional technique used to stimulate the lumbar dermatomes is by stimulation of the dorsal columns of the spinal cord. Until recently, stimulation of nerve roots had not been successfully accomplished. We had performed selective nerve root cannulations for the placement of temporary catheters at cervical, thoracic, lumbar, and sacral levels in chronic pain patients using a caudad rather than craniad approach. We hypothesized that by stimulating the nerve roots we could improve paresthesia coverage in areas which cannot be covered effectively by spinal cord stimulation (SCS). To test this hypothesis, we have performed trials of nerve root stimulation (NRS) in patients who had failed SCS, or who were not candidates for SCS because their pain was otherwise inaccessible to stimulation. Methods. Five patients who had been unresponsive to conservative treatment, surgery, or SCS underwent 7-day trials with NRS. The diagnoses included: ilioinguinal neuralgia, discogenic low back pain, failed back syndrome, vulvodynia, and interstitial cystitis. We collected paresthesia maps, pain maps, pain visual analog scale (VAS) scores, and patient satisfaction ratings. Results. Paresthesia coverage was above 75% in all patients. VAS scores declined from a mean of 9 ± 1.0 to 2.4 ± 2.1 (p < 0.05, n= 5), all 5 patients requested permanent implantation, and 4 have been implanted so far. Conclusions. Lumbar and sacral NRS trials resulted in adequate paresthesia coverage and effective pain relief in all 5 patients. Further clinical trials to evaluate long-term success rates and safety are indicated. Detailed mapping studies are needed to evaluate the relationship between electrode placement and paresthesia patterns as well as the optimal stimulation parameters.     

Multiple Program Spinal Cord Stimulation in the Treatment of Chronic Pain: Follow-Up of Multiple Program SCS

Objective. Follow-up of 80 patients using multiple program spinal cord stimulation (SCS). Methods. For 30 months, we followed 80 chronic pain patients who had undergone SCS implantations at our center. Thirty-six patients had Failed Back Surgery Syndrome (FBSS). Patients were evaluated in patient-controlled stimulation mode (patients can select one of several specific programs in response to their activities and pain level). We collected visual analog pain scores, patient satisfaction scores, pain maps, and paresthesia maps. Results. We previously reported our preliminary findings (Neuromodulation 1998;1 :30–45). At 24 months all patients were using more than one program. At 30 months, 62 patients (76%) were using more than two programs as their preferred stimulation mode and three patients (4%) were satisfied with only one stimulation program. At 30 months all patients chose patient-controlled stimulation as their preferred mode of stimulation. A total of 18 patients (23%) were explanted. Mean pain scores declined from 8.2 at baseline to 4.8 (p < 0.05, n= 79). Paresthesia overlap was 91% (n= 79). Of the patients with FBSS, 81% reported that they were using their SCS daily. Conclusions. In spinal cord stimulation the use of multiple electrodes and multiple stimulation programs, together with advanced programmability, increases paresthesia overlap, reduces pain scores, and may improve patient satisfaction with SCS therapy. This study indicates a significant patient preference for multiple program SCS, if patients are given the option to choose between a single program SCS system or a multiple program SCS system.     

Percutaneous Implanted Paddle Lead for Spinal Cord Stimulation: Technical Considerations and Long‐Term Follow‐Up

Objectives: Spinal cord stimulation (SCS) is an established method for treatment of chronic pain. Cylindrical‐type leads can be implanted percutaneously. In contrast, paddle leads (lamitrode) require more invasive surgery (i.e., laminotomy or laminectomy) for placement into the epidural space, thereby offering several advantages over percutaneous leads (octrode), including less lead migration and better paresthesia coverage. The goal of this study was to prospectively demonstrate the safety and efficacy of a percutaneous paddle lead for SCS. Materials and Methods: This prospective trial enrolled 81 patients. The mean age was 57 years (range 27–82 years) with an almost equal sex distribution (male 47%, female 53%). Most patients (90%) had failed back surgery syndrome combined with lower extremity pain and lower back pain. A percutaneous paddle lead was implanted using a novel introduction system for percutaneous implantation. All implantations were performed under local anesthesia. Prior to the final implantation of the impulse generator, all patients underwent seven days of trial stimulation with pain assessment using a visual analog scale (VAS). The median follow‐up was 12 months. Results: The data showed favorable clinical outcomes for paresthesia coverage and pain reduction (median VAS 8.4 vs. 2.3), with a risk profile comparable with known percutaneous techniques. Compared with the published data (2–22%), the lead migration rate in this study was low (2.5%). No perioperative complications occurred. Conclusions: This new, minimally invasive percutaneous paddle lead is effective and safe, with a low migration rate. Placement can be done under local anesthesia, allowing an intraoperative assessment of the paresthesia coverage in terms of pain relief. This approach is less invasive and offers a faster and more comfortable procedure compared with laminotomy or laminectomy.     

Spinal Cord Stimulation for Failed Back Surgery Syndrome

Objective. The purpose of this study is to evaluate the effectiveness of modern spinal cord stimulation (SCS) for the treatment of failed back surgery syndrome (FBSS). Materials and Methods. Thirty patients were treated with SCS between December 1992 and January 1998 for low back and radicular pain after multiple failed back surgeries. Permanent systems were implanted if trial stimulation led to > 50% pain reduction. Median long‐term follow‐up was 34 months (range, 6–66 months). Severity of pain was determined postoperatively by a disinterested third party. Results. Overall, 12 of the 16 patients (75%) who received permanent implants continued to report at least 50% relief of pain at follow‐up. All six patients who underwent placement of laminectomy‐styled electrode for SCS in the thoracic region had > 50% pain relief at long‐term follow‐up. Visual analog scores decreased an average of 3.2 (from 8.6 preoperatively to 5.4 postoperatively). Patients undergoing SCS placement via laminectomy in the thoracic region experienced an average decrease of 4.9 in VAS, whereas those who underwent percutaneous placement of thoracic leads had an average decrease of 2.5. Conclusions. SCS is an effective treatment for chronic low back and lower extremity pain which is refractory to conservative therapy and which is not amenable to corrective anatomic surgery. Though our patient population is small, our results imply that the laminectomy‐style electrodes in the thoracic region achieve better long‐term effectiveness than percutaneous leads.     

Transverse Tripolar Spinal Cord Stimulation: Results of an International Multicenter Study

Experienced neurosurgeons at eight spinal cord stimulation centers in the United States, Canada, and Europe participated in a study from 1997 to 2000 investigating the safety, performance, and efficacy of a Transverse Tripolar Stimulation (TTS) system invented at the University of Twente, the Netherlands. This device was proposed to improve the ability of spinal cord stimulation to adequately overlap paresthesia to perceived areas of pain. Fifty‐six patients with chronic, intractable neuropathic pain of the trunk and/or limbs more than three months’ duration (average 105 months) were enrolled with follow‐up periods at 4, 12, 26, and 52 weeks. All patients had a new paddle‐type lead implanted with four electrodes, three of them aligned in a row perpendicular to the cord. Fifteen of these patients did not undergo permanent implantation. Of the 41 patients internalized, 20 patients chose conventional programming using an implanted pulse generator to drive four electrodes, while 21 patients chose a tripole stimulation system, which used radiofrequency power and signal transmission and an implanted dual‐channel receiver to drive three electrodes using simultaneous pulses of independently variable amplitude. On average, the visual analog scale scores dropped more for patients with TTS systems (32%) than for conventional polarity systems (16%). Conventional polarity systems were using higher frequencies on average, while usage range was similar. Most impressive was the well‐controlled “steering” of the paresthesias according to the dermatomal topography of the dorsal columns when using the TTS‐balanced pulse driver. The most common complication was lead migration. While the transverse stimulation system produced acceptable outcomes for overall pain relief, an analysis of individual pain patterns suggests that it behaves like spinal cord stimulation in general with the best control of extremity neuropathic pain. This transverse tripole lead and driving system introduced the concept of electrical field steering by selective recruitment of axonal nerve fiber tracts in the dorsal columns.     

Evolving Patterns of Spinal Cord Stimulation in Patients Implanted for Intractable Low Back and Leg Pain

The objective of this study was to examine the programming strategies used in patients with intractable low‐back pain treated with epidural spinal cord stimulation (SCS) utilizing paddle electrodes and a radio frequency (RF) stimulator. Programming strategies were examined in a group of patients implanted with a 16‐contact paddle electrode and a dual channel RF receiver to treat chronic low‐back pain. Baseline data included previous surgical history information, leg and low back pain severity and characteristics, and routine demographic information. Outcome measurements included the visual analog scale (VAS) 1 , patient pain relief rating scale, and programming parameters. Patients rated their pain relief on a 5‐point scale where 4 = excellent, 3 = good, 2 = fair, 1 = poor and 0 = none. Success was determined to be a pain relief score of “fair” or above. Data were collected during patient visits or by mail, at approximately 6, 12, and 24 months, postoperatively. Immediate postop data were available in 16 patients, 6‐month data in 21 patients, 1‐year data in 20 patients, and 2‐year data in 10 patients, and analyzed for the purposes of examining programming strategies. The most common location for the tip of the electrode (lead) was found to be in the middle of the 8th thoracic vertebrae (N = 26). At the immediate postop assessment, the majority of cathodes were activated in the upper half of T9. By the 6‐month follow‐up, the majority of cathodes had shifted to the bottom of T9 and top of T10. Overall 88% of cathode locations were changed at one or more study visits. At 2 years, 86% of the programs used four or more active contacts. At 6 months, 83% of the patients reported that the therapy was a success, at 1 year, success was 94%, and by 2 years, success was 75%. Both SCS and chronic pain are dynamic processes. Complex pain patterns, such as the ones of patients who have pain in the low back and in one or both lower extremities, require a high degree of flexibility in the implanted SCS system. The system must provide the capability to redirect the current electronically over at least two segments of the spinal canal, to electronically steer the current in a medio‐lateral direction, and to activate multiple electrical contacts simultaneously. The willingness and ability to provide extensive reprogramming in the long term follow‐up is also of the utmost importance. Pain and its treatment with SCS is a dynamic process.     

Treatment of Failed Back Surgery Syndrome Patients with Low Back and Leg Pain: A Pilot Study of a New Dual Lead Spinal Cord Stimulation System

Objective. Treatment of pain associated with failed back surgery syndrome was evaluated in a pilot clinical study of a new dual lead spinal cord stimulation (SCS) system. Methods. The following data was retrospectively sought from 20 non-randomized patients at 2 centers treated by the new SCS system, instead of an implantable drug pump: 1) prior back surgeries, 2) pain and paresthesia mapping, 3) VAS ratings, 4) medication use, 5) sleep patterns, 6) physical abilities, 7) hardware problems, and 8) willingness to repeat the procedure. Two-year follow-up was sought from all patients. Results. The new dual lead SCS system provided good low back and leg paresthesia coverage. Patients reported having less pain and using fewer analgesics and narcotics during follow-up, compared to their preimplant experience. These improvements were statistically significant. Patients also improved their sleep and physical abilities during follow-up. While external hardware problems occurred, 65% of dual lead SCS patients were willing to repeat the SCS implant procedure. Conclusions. Dual lead stimulation proved beneficial for patients with low back and leg pain associated with failed back surgery syndrome.     

Continuous Versus Intermittent Spinal Cord Stimulation: An Analysis of Factors Influencing Clinical Efficacy

Objectives: Spinal cord stimulation (SCS) has, for decades, been shown to be successful in a variety of chronic neuropathic pain syndromes. However, there is a paucity of reports in the literature comparing different stimulation patterns. The impact of different stimulation patterns upon outcome remains to be determined, as well as how the latter is influenced by the duration of the post‐SCS pain‐free interval. Materials and Methods: Data from 61 patients (of 71 eligible patients) were collected by means of a telephone interview. These data included the pattern of stimulation (intermittent or continuous), the intensity of stimulation with regard to threshold, the mean, maximal, and minimal pain strength on a numerical rating scale with and without stimulation, the average duration and number of daily stimulation intervals, the average duration of the pain‐relieving effect after switching off the impulse generator, the pain medication intake, the extent of paresthesia coverage, unpleasant side effects, and patient satisfaction. Results: The average improvement in pain score following SCS was 3.10 (50.61%). Twenty‐four patients (39.3%) performed continuous stimulation, and 37 patients (60.7%) performed intermittent stimulation. Patients who performed continuous stimulation had significantly shorter pain‐free intervals following the cessation of stimulation. These patients also showed a tendency toward higher pain scores with and without stimulation, which was not statistically significant. There were no significant differences in pain scores, duration of pain relief, and usage of the stimulation system between patients with different diagnoses and lead locations. Conclusion: Our data showed an equal effectiveness of SCS in the intermittent and in the continuous stimulation mode. The duration of the post‐SCS pain‐free interval may be predictive for the choice of the most effective individual stimulation pattern and deserves further investigation.     

Subcutaneous Peripheral Nerve Stimulation with Inter‐lead Stimulation for Axial Neck and Low Back Pain: Case Series and Review of the Literature

Objectives: While pain in the extremities often responds to treatment using spinal cord stimulation (SCS), axial pain is notoriously refractory to SCS. Interest in subcutaneous peripheral nerve stimulation (SQ PNS) as an alternative to SCS has emerged, but the most appropriate electrode locations and neurostimulator programming techniques are not yet clear. Methods: A retrospective review was conducted of consecutive patients evaluated from August 2009 to December 2010 who had undergone trial of SQ PNS with inter‐lead stimulation for axial spine pain. Patients proceeding to implant were followed postoperatively with routine clinical visits and a survey form at last follow‐up. Ultrasound was used intraoperatively to ensure placement of electrodes at the appropriate depth in patients with larger body mass index. Primary outcome was patient‐reported pain relief at last follow‐up. Literature review was conducted by searching MEDLINE (1948–present) and through an unstructured review by the authors. Results: Ten patients underwent trial of SQ PNS and six proceeded to permanent implantation. Fifty percent (3/6) of implanted patients preferred neurostimulation programming that included inter‐lead stimulation (“cross‐talk”). Average duration of postoperative follow‐up was 4.5 months (range 2–9 months). Average patient‐reported pain relief at last follow‐up was 45% (range 20–80%). One patient required re‐operation for migration. Patients not proceeding to implant had paresthesia coverage but no analgesia. Conclusion: SQ PNS is a promising therapy for axial neck and back pain based on a small cohort of patients. Ultrasound was useful to assist with electrode placement at the most appropriate depth beneath the skin. While inter‐lead stimulation has been preferred by patients in published reports, we did not find it clearly influenced pain relief. Future investigations should include a randomized, controlled study design, as well as defined implantation technique and neurostimulator programming algorithms.     

Efficacy of a Single,Percutaneous, Across Midline,Octrode® Lead Using a “Midline Anchoring” Technique in the Treatment of Chronic Low Back and/or Lower Extremity Pain: A Retrospective Study

Introduction. Spinal cord stimulation is a widely used treatment modality for chronic pain, especially failed back surgery syndrome. However, migration of the lead or leads, coverage of axial pain, and the selection of an optimal system configuration continue to be subjects for serious debate. Materials and Methods. A retrospective study of the use of the method of “midline anchoring” of a single Octrode® lead, in 54 patients with low back and/or lower extremity pain, was done to assess the efficacy of this technique. Results. During the study period of 9.3 months, only a 4% revision rate was reported. Reduction in pain of more than 50% and individual patient satisfaction scores were very high (85% and 87%, respectively). Successful bilateral pain coverage was obtained with a single Octrode® lead. The lower extremities and buttocks area were captured in 89% of the patients. Axial pain coverage was achieved in the majority of the patients, with 71% reporting adequate coverage of the upper lumbar spine. A “guarded cathode” array was used in the vast majority of the cases, with a relatively low position of the lead. Conclusions. “Midline anchoring” of the spinal cord stimulation lead is an effective implantation technique, allowing the use of a single, percutaneous, Octrode® lead, while preventing lead migration and allowing capture of axial and lower extremity pain, unilateral as well as bilateral. This study revives the idea of a single lead as a possible optimal configuration.     

Dual Spinal Cord Stimulation for Complex Pain: Preliminary Study

Objectives To retrospectively analyze by indices of success, patients with chronic complex pain, including, axial low back pain, receiving dual spinal cord stimulation (SCS) systems. Methods Eighteen patients with dual spinal cord stimulators have been retrospectively and nonrandomly analyzed. The preponderance of patients in our study group had failed back surgery syndrome (FBSS). Parameters of success of our therapy included reduction of medication, if any, complications, if any, and satisfaction with therapy and improvement in the quality of life, measured by a visual analogical scale (VAS) from 0 to 10. Patients were asked to rate their overall experience with their SCS systems and were divided into four separate groupings according to their overall rating of their therapy. These four groupings included therapy ratings of excellent (70–100%), good (> 50%), fair (< 50%), and poor (< 30%). Satisfaction with therapy and improvement in quality of life were evaluated on a five‐point scale. Patients were asked to rate changes in their quality of life after therapy using the following normative scale: much better, better, no change, worse, and much worse. All the patients in our study were asked if they would repeat their therapy with dual spinal cord stimulation. Results Paresthesia coverage, overlapping the reported painful region, was obtained in 80% of the patients in our study. The VAS decreased an average of 5.6 (range 2–10) after 6 months and 4.9 (range 2–8) at the end of the study. Six patients (37.5%) reported excellent results; four patients (25%) reported good; three (18.7%), fair and poor. Seventy percent of the patients were satisfied with the treatment and reported an increase in their quality of life. Medications were reduced in 75% of the patients. Thirteen (81%) patients with dual lead SCS therapy were willing to repeat the SCS implant procedure. Complications occurred in 43.7%. Conclusions Dual spinal cord stimulation is appropriate and efficacious for treating complex pathology and complex pain that including pain of the low, axial back.     

Spinal Cord Stimulation With a Dual Quadripolar Surgical Lead Placed in General Anesthesia Is Effective in Treating Intractable Low Back and Leg Pain

Objectives. Spinal cord stimulation has been used extensively for failed back surgery syndrome, although dominant axial low back pain is difficult to treat effectively with this modality. The use of a surgically placed, double, quadripolar lead may result in better paresthesia of the low back, therefore enhancing outcomes in this difficult to treat population. Materials and Methods. Accordingly, this prospective study was designed to assess the effectiveness of placing such a lead at the T8–T10 level under general anesthesia without intraoperative testing for concordancy of paresthesia distribution. Results. The study showed that 70% of patients had “good” or “complete” long‐term pain relief after placement of a surgically placed dual quadripolar lead under general anesthesia and analgesic consumption decreased significantly. The ability to lead a more active and social life was increased and 85% of patients said they would undergo spinal cord stimulation again. Placing the lead higher in the spinal canal (T8) resulted in a tendency for better paresthesia coverage of the low back when compared to lower lead placements. Conclusions. Placing a double quadripolar paddle lead under general anesthesia resulted in good clinical outcome similar to other implant techniques.     

Spinal Cord Stimulation Versus Re-operation in Patients With Failed Back Surgery Syndrome: An International Multicenter Randomized Controlled Trial (EVIDENCE Study)

Objective: This paper presents the protocol of the EVIDENCE study, a multicenter multinational randomized controlled trial to assess the effectiveness and cost‐effectiveness of spinal cord stimulation (SCS) with rechargeable pulse generator versus re‐operation through 36‐month follow‐up in patients with failed back surgery syndrome. Study Design: Study subjects have neuropathic radicular leg pain exceeding or equaling any low back pain and meet specified entry criteria. One‐to‐one randomization is stratified by site and by one or more prior lumbosacral operations. The sample size of 132 subjects may be adjusted to between 100 and 200 subjects using a standard adaptive design statistical method with pre‐defined rules. Crossover treatment is possible. Co‐primary endpoints are proportion of subjects reporting ≥50% leg pain relief without crossover at 6 and at 24 months after SCS screening trial or re‐operation. Insufficient pain relief constitutes failure of randomized treatment, as does crossover. Secondary endpoints include cost‐effectiveness; relief of leg, back, and overall pain; change in disability and quality of life; and rate of crossover. We are collecting data on subject global impression of change, patient satisfaction with treatment, employment status, pain/paresthesia overlap, SCS programming, and adverse events. Discussion: As the first multicenter randomized controlled trial of SCS versus re‐operation and the first to use only rechargeable SCS pulse generators, the EVIDENCE study will provide up‐to‐date evidence on the treatment of failed back surgery syndrome.     

A New and Alternative Leads Positioning for Complex Regional Pain Syndrome Treatment: Paraforaminal Stimulation

We present a case of a female patient suffering from type I complex regional pain syndrome (CRPS) who developed “mirror imaging” of her CRPS and was successfully treated with dual spinal cord stimulation (SCS) in the paraforaminal epidural space. This patient initially had unilateral pain that was unsuccessfully treated with midline SCS and single‐lead lateral epidural lead placement “paraforaminally.” One year later, because we believed that paraforaminal stimulation would preferentially stimulate primary sensitized afferents innervating the painful area, we reperformed SCS with two leads positioned laterally and paraforaminally close to the roots within the epidural space. After repositioning and after 1 year of paraforaminal stimulation, there was significant improvement in the patient's symptoms, resolving all unilateral and “mirrored” symptoms. We conclude that paraforaminal stimulation may be a valid therapeutic option for the treatment of CRPS.     

Epidural Spinal Cord Stimulation with a Multiple Electrode Paddle Lead Is Effective in Treating Intractable Low Back Pain

The objective of this paper is to examine the outcomes of patients with intractable low‐back pain treated with epidural spinal cord stimulation (SCS) utilizing paddle electrodes and a radio frequency (RF) stimulator. A multicenter prospective study was performed to collect data from patients suffering from chronic low‐back pain. The study was designed to collect data from 60 patients at four centers and examine their outcomes at, or up to two years post implantation. Patients' participation included written responses to a series of preoperative questionnaires that were designed to collect previous surgical history information, leg and low back pain characteristics, and routine demographic information. Outcome measurements included the visual analog scale (VAS), the Oswestry Disability Questionnaire, the Sickness Impact Profile (SIP), and a patient satisfaction rating scale. Data were collected at each site during patient visits or by mail, at approximately six months, 12 months, and 24 months. A total of 44 patients have been implanted with a SCS system at the time of this writing. Follow‐up data were available for 41 patients. Preoperatively, all patients reported more than 50% of their pain in the low back. All patients had pain in both their backs and legs. All patients showed a reported mean decrease in their 10‐point VAS scores compared to baseline. The majority of patients reported fair to excellent pain relief in both the low back and legs. At six months 91.6% of the patients reported fair to excellent relief in the legs and 82.7% of the patients reported fair to excellent relief in the low back. At one year 88.2% of the patients reported fair to excellent relief in the legs and 68.8% of the patients reported fair to excellent relief in the low back. Significant improvement in function and quality of life was found at both the six‐month and one‐year follow‐ups using the Oswestry and SIP, respectively. The majority of patients reported that the procedure was worthwhile (92% at six months, 88% at one year). No patient indicated that the procedure was not worthwhile. We conclude that SCS proved beneficial at one year for the treatment of patients with chronic low back and leg pain.     

Spinal Cord Stimulation for Complex Regional Pain Syndrome I [RSD]: a Retrospective Multicenter Experience from 1995 to 1998 of 101 Patients

Objective. To evaluate effectiveness of spinal cord stimulation (SCS) applied to complex regional pain syndrome I (CRPS I). To analyze trends to focus the design of a multicenter prospective study. Design. Retrospective multicenter series, 3 years. Outcome measures. We collected visual analog scales for pain and patient satisfaction data on n= 101 patients. Patients were divided into two groups: Group I had single-lead quadrapolar systems, Group II had dual-lead octapolar systems. Results. Mean pain scores decreased in both groups with a significantly greater decrease in Group II (p < 0.0001). 74.6% of Group II patients preferred multiple programming arrays with 15.5% requiring frequencies > 250Hz.; overall satisfaction scores were 70% in Group I and 91% in Group II (p < 0.05). Conclusions. SCS is an effective treatment of pain in CRPS I. Frequencies > 250Hz were necessary in some patients to maintain or re-establish pain control. Bilateral multielectrode leads appear superior with application of multiple arrays, permitting paresthesia steering without need for surgical revision. A multicenter, prospective design is needed applying dual-lead multichannel systems with high frequency capabilities in the treatment of CRPS I.     

Prospective,Two-part Study of the Interaction Between Spinal Cord Stimulation and Peripheral Nerve Field Stimulation in Patients with Low Back Pain: Development of a New Spinal-Peripheral Neurostimulation Method

Objective: The goal of the study was to assess the efficacy of interaction between spinal cord stimulation (SCS) and peripheral nerve field stimulation (PNFS) and to evaluate a new spinal‐peripheral neuromodulation method for low back pain. Materials and Methods: The prospective two‐part study included patients with low back pain due to failed back surgery syndrome and/or spinal stenosis. In the first part 20 patients were implanted with SCS and PNFS. They selected the best program out of three: SCS alone, PNFS alone, or both together. In the second part another 20 patients with the same implanted leads were selecting between three programs: SCS and PNFS separately, SCS as anode and PNFS as cathode, or in reverse. Results: In the first part 79% of the patients selected simultaneous use of SCS and PNFS. The overall success of the trials was 85%. In the second part communication between SCS and PNFS provided wider coverage of axial pain. The overall success of the trials was 90%. Conclusion: Simultaneous use of SCS and PNFS increase efficacy of both methods for axial back pain. The new SPN method showed great potential in providing coverage for back pain.