The Neurostimulation Appropriateness Consensus Committee (NACC): Recommendations on Best Practices for Cervical Neurostimulation.

INTRODUCTION: The International Neuromodulation Society convened a multispecialty group of physicians based on expertise with international representation to establish evidence-based guidance on the use of neurostimulation in the cervical region to improve outcomes. This Neurostimulation Appropriateness Consensus Committee (NACC) project intends to provide evidence-based guidance for an often-overlooked area of neurostimulation practice. MATERIALS AND METHODS: Authors were chosen based upon their clinical expertise, familiarity with the peer-reviewed literature, research productivity, and contributions to the neuromodulation literature. Section leaders supervised literature searches of MEDLINE, BioMed Central, Current Contents Connect, Embase, International Pharmaceutical Abstracts, Web of Science, Google Scholar, and PubMed from 2017 (when NACC last published guidelines) to the present. Identified studies were graded using the US Preventive Services Task Force criteria for evidence and certainty of net benefit. Recommendations are based on the strength of evidence or consensus when evidence was scant. RESULTS: The NACC examined the published literature and established evidence- and consensus-based recommendations to guide best practices. Additional guidance will occur as new evidence is developed in future iterations of this process. CONCLUSIONS: The NACC recommends best practices regarding the use of cervical neuromodulation to improve safety and efficacy. The evidence- and consensus-based recommendations should be utilized as a guide to assist decision making when clinically appropriate.

Persistent Spinal Pain Syndrome: A Proposal for Failed Back Surgery Syndrome and ICD-11.

OBJECTIVE: For many medical professionals dealing with patients with persistent pain following spine surgery, the term Failed back surgery syndrome (FBSS) as a diagnostic label is inadequate, misleading, and potentially troublesome. It misrepresents causation. Alternative terms have been suggested, but none has replaced FBSS. The International Association for the Study of Pain (IASP) published a revised classification of chronic pain, as part of the new International Classification of Diseases (ICD-11), which has been accepted by the World Health Organization (WHO). This includes the term Chronic pain after spinal surgery (CPSS), which is suggested as a replacement for FBSS. METHODS: This article provides arguments and rationale for a replacement definition. In order to propose a broadly applicable yet more precise and clinically informative term, an international group of experts was established. RESULTS: 14 candidate replacement terms were considered and ranked. The application of agreed criteria reduced this to a shortlist of four. A preferred option-Persistent spinal pain syndrome-was selected by a structured workshop and Delphi process. We provide rationale for using Persistent spinal pain syndrome and a schema for its incorporation into ICD-11. We propose the adoption of this term would strengthen the new ICD-11 classification. CONCLUSIONS: This project is important to those in the fields of pain management, spine surgery, and neuromodulation, as well as patients labeled with FBSS. Through a shift in perspective, it could facilitate the application of the new ICD-11 classification and allow clearer discussion among medical professionals, industry, funding organizations, academia, and the legal profession.

Peripheral Nerve Field Stimulation for Chronic Back Pain: Therapy Outcome Predictive Factors.

OBJECTIVE: To identify variables that influence pain reduction following peripheral nerve field stimulation (PNFS) in order to identify a potential responder profile. METHODS: Exploratory univariate and multivariate (random forest) analyses were performed separately on 2 randomized controlled trials and a registry; all included patients with chronic back pain, mainly failed back surgery syndrome. An international expert panel judged the clinical relevance of variables to identify responders by consensus. RESULTS: Variables identified that may help predict PNFS success in patients with back pain include patient and pain characteristics (age, time since onset of pain and spinal surgery, pain medication history, position and size of pain area, pain severity, mixed nociceptive/neuropathic pain, health-related quality of life, depression, functional disability, and leg pain status), implant procedure variables (the number and position of leads, paresthesia coverage, and amount of pain relief during the trial), and programming (number of programs, cathodes, and anodes; pulse rate; pulse width; and percentage of device usage). CONCLUSIONS: While these analyses are exploratory and restricted to a limited sample size, they suggest variables that may play a role in predicting a therapeutic response. These results, however, are informative only and should be cautiously interpreted. Future research to validate the variables in a clinical study is needed.

Intraoperative electromyography as an adjunct to sacral neuromodulation for chronic pelvic pain.

OBJECTIVE: Sacral neuromodulation is an established technique for the treatment of chronic intractable pelvic and anorectal pain. Stimulation of sacral roots S2-4 is typically associated with therapeutic paresthesia, while stimulation of the S1 nerve root causes unwanted leg paresthesia. Here we describe and evaluate the use of intraoperative electromyography (EMG) of the gastrocnemius, foot intrinsic muscles, and anal sphincter as an adjunct to epidural stimulator placement. MATERIALS AND METHODS: Two female patients with intractable pelvic pain underwent implantation of sacral epidural paddles with intraoperative EMG. These cases were retrospectively reviewed to evaluate intraoperative EMG activation and therapeutic paresthesia. RESULTS: We found cephalad-to-caudal transitions in EMG activation with stimulation: medial gastrocnemius to foot intrinsics to anal sphincter. Coactivation of foot intrinsic muscles with anal sphincter and absence of medial gastrocnemius stimulation correlated with therapeutic perineal paresthesia. CONCLUSIONS: Intraoperative EMG of the gastrocnemius, foot intrinsics, and anal sphincter may be a useful adjunct to sacral stimulation for pelvic pain.

Principles of cord activation during spinal cord stimulation.

OBJECTIVES: This study aims to review some of the basic principles of extracellular electrical stimulation used in spinal cord stimulation therapy for intractable pain. MATERIALS AND METHODS: Spinal cord stimulation has been used therapeutically for more than 40 years. We present the basic principles of extracellular stimulation on which the therapy is based, describe electrode operation and current configurations, and explain the implications of these technological advances for the clinical application of spinal cord stimulation. RESULTS: Computational studies of coupled electric field and neuron models have significantly advanced our understanding of the therapeutic effects of neurostimulation. Neurostimulation is intended to obtain maximal selectivity of desired neural elements while avoiding those resulting in side-effects. Preferential stimulation of the dorsal columns is achieved with a narrow spacing between electrodes using bipolar or tripolar electrode configurations. Stimulus parameters such as amplitude and pulse width may be used to selectively control which neuronal elements are excited during stimulation. CONCLUSIONS: A better understanding of the interaction between electric fields and the targeted neural elements may guide the selection of stimulation parameters in contemporary neurostimulators and lead to continuing advances in engineering solutions for therapeutic spinal cord stimulation.

Using peripheral nerve stimulation (PNS) to treat neuropathic pain: a clinical series.

OBJECTIVE: We examined the efficacy of peripheral nerve stimulation (PNS) in treating neuropathic and causalgic pain, with a stimulation system specifically designated for PNS itself. MATERIALS AND METHODS: A total of 15 patients were treated between January 2011 and March 2012. The percutaneous lead was implanted on the nerves, exposing it on the electrical nerve stimulation (ENS) guide. The average numeric rating scale (NRS) preimplant was 8.46, and the oxycodone intake was 90 mg/day. RESULTS: Of the 15 patients, 3 failed the trial phase and 12 were implanted with a permanent pulse generator (Lightpulse 100, Neurimpulse, Rubano, PD, Italy). At an average of 9.3 months of follow-up, the average NRS score was 3.46 (p < 0.001), and the average Likert scale score at 7 points was 5.91. Nine patients were working prior to their injuries, seven of whom returned to work after receiving an implant. The average oxycodone consumption decreased to 30 mg/day, and the pregabalin dosage decreased to 75 mg/day. CONCLUSION: Our study results confirm that PNS is an effective modality in managing severe neuropathic and intractable pain following multiple joint surgeries that are complicated by causalgic pain.

Primary 3-Month Outcomes of a Double-Blind Randomized Prospective Study (The QUEST Study) Assessing Effectiveness and Safety of Novel High-Frequency Electric Nerve Block System for Treatment of Post-Amputation Pain.

Purpose: This multicenter, randomized, double-blinded, active sham-controlled pivotal study was designed to assess the efficacy and safety of high-frequency nerve block treatment for chronic post-amputation and phantom limb pain. Patients and Methods: QUEST enrolled 180 unilateral lower-limb amputees with severe post-amputation pain, 170 of whom were implanted with the Altius device, were randomized 1:1 to active-sham or treatment groups and reached the primary endpoint. Responders were those subjects who received ≥50% pain relief 30 min after treatment in ≥50% of their self-initiated treatment sessions within the 3-month randomized period. Differences between the active treatment and sham control groups as well as numerous secondary outcomes were determined. Results: At 30-min, (primary outcome), 24.7% of the treatment group were responders compared to 7.1% of the control group (p=0.002). At 120-minutes following treatment, responder rates were 46.8% in the Treatment group and 22.2% in the Control group (p=0.001). Improvement in Brief Pain Inventory interference score of 2.3 ± 0.29 was significantly greater in treatment group than the 1.3 ± 0.26-point change in the Control group (p = 0.01). Opioid usage, although not significantly different, trended towards a greater reduction in the treatment group than in the control group. The incidence of adverse events did not differ significantly between the treatment and control groups. Conclusion: The primary outcomes of the study were met, and the majority of Treatment patients experienced a substantial improvement in PAP (regardless of meeting the study definition of a responder). The significant in PAP was associated with significantly improved QOL metrics, and a trend towards reduced opioid utilization compared to Control. These data indicate that Altius treatment represents a significant therapeutic advancement for lower-limb amputees suffering from chronic PAP.

Spinal cord stimulation (SCS) in conjunction with peripheral nerve field stimulation (PNfS) for the treatment of complex pain in failed back surgery syndrome (FBSS).

BACKGROUND: Failed back surgery syndrome (FBSS) is a well-defined pathologic condition observed over many years. DESIGN: We have investigated the effect of spinal cord stimulation (SCS) with peripheral nerve field stimulation (PNfS) in eight patients with FBSS. OUTCOME MEASURE: The following parameters were collected and analyzed: The pain intensity score on a 0-10 numbering rating scale (NRS), the psychologic profile with Beck Depression Inventory (BDI), the pain quality with McGill Pain Questionnaire-short form (MGPQ-sf), the back pain with Oswestry scale score (OS), and the health general quality pattern with QualityMetric's SF-36v2(®) Health Survey. PATIENTS: Eight patients with low back and radicular pain in FBSS are reported. The mean duration of pain was 6.7 months, and the mean NRS score was 9.5, BDI 28.8, MGPQ-sf 16.8, OS 44.5, and SF-36 score was 72.8. The average drug intake of opioids was 250 mg/day. INTERVENTION: In six patients, two octopolar leads were placed in epidural space at D7-D8 and D8-D9, in conjunction with two octopolar leads placed in lumbar-sacral subcutaneous space (Precision System, Boston Scientific, Valencia, CA, USA), and in two patients, a two tetrapolar leads was placed in epidural space at D8-D9 with two tetrapolar leads (Pisces Quad, Plus, Medtronic Inc., Minneapolis, MN, USA) placed in lumbar-sacral subcutaneous space (Restore Ultra, Medtronic Inc., Minneapolis, MN, USA). RESULTS: After one year mean of follow-up, the mean NRS score was 4, BDI 8, MGPQ-sf 5, OS 21, and the SF-36 score was increased at 108.5. The mean drug intake of opioids was decreased at 20 mg/day. CONCLUSION: The combination of SCS and PNfS, using the latest rechargeable systems, may be a valid therapeutic strategy in FBSS.

Peripheral nerve field stimulation for the management of localized chronic intractable back pain: results from a randomized controlled study.

OBJECTIVES: Improved device technology has caused a renewed interest in peripheral nerve field stimulation (PNfS). This study sought to obtain preliminary estimates of the safety and efficacy of PNfS in patients with localized chronic intractable pain of the back. MATERIALS AND METHODS: This Institutional Review Board-approved, prospective, randomized, controlled, crossover study consisted of two phases. During phase I, patients rotated through four stimulation groups (minimal, subthreshold, low frequency, and standard stimulation). If a 50% reduction in pain was achieved during any of the three active stimulation groups (responder), the patient proceeded to phase II, which began with implant of the permanent system and lasted 52 weeks. The primary endpoint was a reduction in pain, assessed by the visual analog scale (VAS). Analysis of variance, including the effects of patient, treatment, and study period, was used for phase I results. Phase II results were analyzed by paired t-tests. RESULTS: A total of 44 patients were enrolled at five sites. Of these patients, 32 were implanted with a trial system and 30 completed phase I. During phase I, there were significant differences in mean VAS scores between minimal stimulation and subthreshold stimulation (p = 0.003), low frequency stimulation (p < 0.001), and standard stimulation (p < 0.001). Twenty-four patients were classified as responders to the therapy, and 23 patients received permanent system placement. Significant differences in VAS scores were observed between baseline and all follow-up visits during phase II (p < 0.001) CONCLUSIONS: The results provide evidence to support safety and effectiveness of PNfS as an aid in the management of chronic, localized back pain.

Incidence and avoidance of neurologic complications with paddle type spinal cord stimulation leads.

INTRODUCTION: While reference is frequently made to the risk of spinal cord or nerve root injury with the surgical implantation of paddle type spinal cord stimulation (SCS) electrodes, data are lacking on the frequency, causes, and prevention of these complications. METHODS: To determine the incidence and frequency of neurologic complications, we performed 1) a comprehensive analysis of the literature to determine the incidence of complications that have caused or could lead to neurologic injury; 2) an analysis of the US Food and Drug Administration Manufacturer and User Facility Device Experience (MAUDE) data base; and 3) an investigation of manufacturers' data on surgically implanted paddle electrodes. We then convened an expert panel of neurosurgeons experienced in the surgical implantation of paddle electrodes to provide recommendations to minimize the risk of neurologic injury. RESULTS: The scientific literature describes the breadth of neurologic complications that can result from SCS electrode implantation but does not provide interpretable data with respect to the incidence and frequency of these complications. The MAUDE data base is not constructed to be sensitive or specific enough to provide these critical data. Primary data show a risk of neurologic injury from implantation of paddle electrodes below 0.6%. DISCUSSION: Preoperative, intraoperative, and postoperative measures to further minimize this risk are described. CONCLUSIONS: This investigation, the first comprehensive evaluation of the incidence and frequency of neurologic injury as a result of SCS paddle electrode implantation, suggests that neurologic injury is a rare, but serious, complication of SCS. The incidence of these complications should be decreased by the adoption of approaches that improve procedural safety and by careful patient follow-up and complication management. Physicians should be aware of these approaches and take every precaution to reduce the risk of neurologic injury. Physicians also should report any adverse event leading to injury or death and work together to improve access to these data.

Spinal cord stimulation as alternative treatment for chronic post-herniorrhaphy pain.

OBJECTIVE: Our goal was to determine the efficacy of spinal cord stimulation for patients with intractable post-herniorrhaphy pain which conventional treatment failed to ameliorate. PROCEDURE: The patients underwent an uneventful spinal cord stimulator (SCS) trial with percutaneous placement of two eight-electrode epidural leads (Medtronic Inc, Minneapolis, MN, USA) to level T7-T8-T9. RESULTS: Upon experiencing excellent pain relief over the next two days during the trial, the patients were implanted with permanent leads and rechargeable or non-rechargeable generators two to four weeks later and reported sustained pain relief during following 12 months after implantation. CONCLUSION: We conclude that SCS offers an alternative treatment option for intractable post-herniorrhaphy pain. This type of treatment should be considered for use in a select group of patients when all conventional treatments failed.

Perception threshold and electrode position for spinal cord stimulation.

The perception threshold for epidural spinal cord stimulation in chronic pain management was analyzed on 3,923 testing data obtained from 136 implanted patients. The initial areas of paresthesiae due to stimulation were recorded and reported as the stimulation map according to the location of electrodes. Measurement of dorsal thickness of the cerebrospinal fluid (CSF) layer was obtained from 26 subjects using magnetic resonance imaging (MRI). The results indicate that the perception threshold is a function of the spinal level of the implanted electrodes, of the mediolateral position in the spinal canal and the contact separation of electrode. Differences in perception threshold at various vertebral levels are mainly due to varying depths of the dorsal CSF layer. The medially placed electrodes caudal to the mid-cervical levels have a higher perception threshold than more laterally placed ones. The electrodes at high and mid-cervical levels, however, have a smaller perception threshold if placed medially. The information obtained from this investigation has important implications for the design of a new-generation stimulation system and clinical application to maximize the longevity of the power source.

Bilateral cingulumotomy in the treatment of reflex sympathetic dystrophy.

Bilateral anterior cingulumotomy has been used to treat psychiatric diseases and chronic pain. We report an interesting case involving a young woman who underwent cingulumotomy for the treatment of intractable total body pain secondary to generalized reflex sympathetic dystrophy. Her initial response after two procedures was excellent though 1 year later her pain recurred and was resistant to a subsequent cingulumotomy.

Automated, patient-interactive, spinal cord stimulator adjustment: a randomized controlled trial.

OBJECTIVE: Programmable, multicontact, implanted stimulation devices represent an important advance in spinal cord stimulation for the management of pain. They facilitate the technical goal of covering areas of pain by stimulation-evoked paresthesiae. Adjustment after implantation requires major investments of time and effort, however, if the capabilities of these devices are to be used to full advantage. The objective of maximizing coverage should be met while using practitioners' time efficiently. METHODS: We have developed a patient-interactive, computerized system designed for greater ease and safety of operation, compared with the standard external devices used to control and adjust implanted pulse generators. The system automatically and rapidly presents to the patient the contact combinations and pulse parameters specified by the practitioner. The patient adjusts the amplitude of stimulation and then records drawings of stimulation paresthesiae (for comparison with pain drawings), followed by visual analog scale ratings for each setting. Test results are analyzed and sorted to determine the optimal settings. We compared the automated, patient-interactive system with traditional, practitioner-operated, manual programming methods in a randomized controlled trial at two study centers, with 44 patients. RESULTS: The automated, patient-interactive system yielded significantly (P < 0.0001) better technical results than did traditional manual methods, in achieving coverage of pain by stimulation paresthesiae (mean 100-point visual analog scale ratings of 70 and 46, respectively). The visual analog scale ratings were higher for automated testing for 38 patients, higher for manual testing for 0 patients, and equal (tied) for 6 patients. Multivariate analysis demonstrated that the advantage of automated testing occurred independently of practitioner experience; the advantage was significantly greater, however, for experienced patients. The rate of testing (number of settings tested per unit time) was significantly (P < 0.0001) greater for the automated system, in comparison with the rate with a human operator using traditional, manual, programming methods (mean of 0.73 settings/min versus 0.49 settings/min). The automated system also identified settings with improved estimated battery life (and corresponding anticipated cost savings). No complications were observed with automated testing; one complication (transient discomfort attributable to excessive stimulation) occurred with manual testing. CONCLUSION: Automated, patient-interactive adjustment of implanted spinal cord stimulators is significantly more effective and more efficient than traditional manual methods of adjustment. It offers not only improved clinical efficacy but also potential cost savings in extending implanted battery life. It has the additional potential advantages of standardization, quality control, and record keeping, to facilitate clinical research and patient care. It should enhance the clinical application of spinal cord stimulation for the treatment of chronic intractable pain.

The psychological assessment of candidates for spinal cord stimulation for chronic pain management.

It is known that, in spite of meeting appropriate clinical criteria for spinal cord stimulation (SCS) and having undergone flawless procedures, a significant number of patients who fail the therapy continues to exist. It is the purpose of this article to focus on the development of psychosocial indicators of success for SCS, if any. Referring to specialist literature authors present a review of what is known, what is not known, and what remains controversial on this topic. After reading this article we hope the reader will understand the importance of a psychological evaluation as part of the development of standards for identifying appropriate patients for this therapy. To improve treatment outcomes of SCS, seems to be essential to perform psychosocial evaluations on all persons clinically indicated for SCS to exclude those patients, who most probably, on a psychosocial level, will fail the procedure. To maximize treatment efficacy, authors believe spinal cord stimulation for chronic pain control must be part of a comprehensive program. An accurate preoperative psychosocial assessment and a course of psychological assistance both before and after therapy seems to be crucial for improving outcomes.

Peripheral subcutaneous stimulation for intractable abdominal pain.

Peripheral subcutaneous stimulation has been utilized for a variety of painful conditions affecting the abdominal wall, including sequelae of hernia repair, painful surgical scars, ilio-inguinal neuritis. It has also occasionally been shown to be effective in patients with intractable abdominal visceral pain. Since this is a very recent modality, no large series or prospective studies exist. The results, however, are promising and certainly warrant further investigation.