The Neurostimulation Appropriateness Consensus Committee (NACC): Recommendations for Surgical Technique for Spinal Cord Stimulation.

INTRODUCTION: The field of neurostimulation for the treatment of chronic pain is a rapidly developing area of medicine. Although neurostimulation therapies have advanced significantly as a result of technologic improvements, surgical planning, device placement, and postoperative care are of equal importance to optimize outcomes. This Neurostimulation Appropriateness Consensus Committee (NACC) project intends to provide evidence-based guidance for these often-overlooked areas of neurostimulation practice. MATERIALS AND METHODS: Authors were chosen based on 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 the last NACC publication in 2017 to the present. Identified studies were graded using the United States Preventive Services Task Force criteria for evidence and certainty of net benefit. Recommendations are based on evidence strength and consensus when evidence was scant. RESULTS: This NACC project provides guidance on preoperative assessment, intraoperative techniques, and postoperative management in the form of consensus points with supportive evidence. These results are based on grade of evidence, strength of consensus, and expert opinion. CONCLUSIONS: The NACC has given guidance for a surgical plan that encompasses the patient journey from the planning stage through the surgical experience and postoperative care. The overall recommendations are designed to improve efficacy and the safety of patients undergoing these neuromodulation procedures and are intended to apply throughout the international community.

Anatomic Lead Placement Without Paresthesia Mapping Provides Effective and Predictable Therapy During the Trial Evaluation Period: Results From the Prospective, Multicenter, Randomized, DELIVERY Study.

OBJECTIVE: The purpose of this study was to compare the trial success rate between anatomic lead placement (AP) and paresthesia-mapped (PM) lead placement techniques for spinal cord stimulation (SCS) using a nonlinear burst stimulation pattern. MATERIALS AND METHODS: Eligible patients with back and/or leg pain with a Numeric Rating Scale (NRS) score of ≥6 who had not undergone previous SCS were enrolled in the study. A total of 270 patients were randomized in a 1:1 ratio to each treatment arm. In the AP group, one lead tip was placed at the mid-body of T8, and the other at the superior endplate of T9. In the PM group, physicians confirmed coverage of the patient's primary pain location. Trial success was a composite of the following: ≥50% patient-reported pain relief at the end of the minimum three-day trial period, physician's recommendation, and patient's interest in a permanent implant. RESULTS: Trial success for AP vs. PM groups was equivalent to 84.4% and 82.3%, respectively. Physicians who performed both techniques preferred AP technique (70% vs. 30%). Procedure times for placement of two leads were 31% shorter in the AP group (p < 0.0001). Decrease in the mean NRS pain score was similar between groups (53.2%, AP group; 53.8%, PM group, p = 0.79). Trial success for patients who went on to an extended trial with tonic stimulation was 50% (5/10) vs. 79% (11/14) for AP group and PM group, respectively (p = 0.2). A total of 13 adverse events were observed (4.5%), most commonly lead migrations and pain around implant site, with no difference between groups. CONCLUSIONS: When using a nonlinear burst stimulation pattern, anatomic or PM lead placement technique may be used. Nonresponders to subthreshold stimulation had a higher conversion rate when a PM technique was used. AP resulted in shorter procedure times with a similar safety profile and was strongly preferred by trialing physicians.

Burst SCS Microdosing Is as Efficacious as Standard Burst SCS in Treating Chronic Back and Leg Pain: Results From a Randomized Controlled Trial.

INTRODUCTION: The burst waveform, a recent innovation in spinal cord stimulation (SCS), can achieve better outcomes than conventional tonic SCS, both for de novo implants and as a salvage therapy. Burst stimulation delivers more energy per second than tonic stimulation, which is a consideration for battery consumption. The clinical effectiveness of an energy-conserving strategy was investigated. METHODS: Subjects were experienced users of BurstDR SCS for back and leg pain. Three 2-week stimulation paradigms were presented in blinded random order: standard (continuously delivered) BurstDR, microdosing A: 5 sec of BurstDR alternating with 5 sec of no stimulation, and microdosing B: 5 sec of BurstDR alternating with 10 sec of no stimulation. The primary outcome for each paradigm was change in pain ratings, and secondary outcomes included changes in scores for quality of life, satisfaction, and preference. RESULTS: Twenty-five subjects assessed all three stimulation paradigms. There were no significant differences in pain (visual analog scale) or quality of life (EQ-5D) when comparing standard burst outcomes with those of microdosing A and, separately, microdosing B. Microdosing paradigms were graded with slightly higher level of satisfaction and were generally preferred above standard burst stimulation. DISCUSSION: These results suggest that the use of energy-efficient burst microdosing stimulation paradigms with alternating stimulation-on and stimulation-off periods can provide clinically equivalent results to standard burst stimulation. This is important for extending SCS battery life. Further research is needed to comprehensively characterize the clinical utility of this approach and the neurophysiological mechanisms for the maintenance of pain relief during stimulation-off periods.

High-Frequency Spinal Cord Stimulation in Surgery-Naïve Patients-A Prospective Single-Center Study.

INTRODUCTION: A multitude of evidence supporting the beneficial effects of spinal cord stimulation (SCS) in patients suffering from chronic pain syndromes following spinal surgery has been published in the last decade. Evidence is scarce, however, for the use of high frequency SCS (HF-SCS) in the treatment of surgery naïve patients suffering from lower back pain (LBP). METHODS: From June 2014 to April 2015, we prospectively enrolled patients suffering from LBP alone or in conjunction with leg pain in a trial of HF-SCS. None of the patients had undergone surgical procedures of the lumbar spine. Patients suffered medically intractable LBP and were deemed ineligible for spine surgery. All patients underwent trial stimulation for at least one week. Pain levels were assessed daily during initial stay, 4 weeks later and then every 3 months. Different preprogrammed modes of HF-SCS were changed if pain persisted or increased during trial or postimplant follow-up (FU). RESULTS: Eight patients (four male, four female) underwent HF-SCS trials. Mean age was 60 ± 4.8 years. Mean numeric rating scale (NRS) baseline intensity for back pain was 8.9 ± 0.23 and 8.1 ± 0.6 for leg pain. All patients achieved meaningful reductions in pain intensities and underwent IPG implantation at a mean interval of 13 days. Mean follow-up was 306 days. Mean back pain reduction from baseline at last follow-up was -4.13 ± 0.85, and -6.2 ± 1.03 for leg pain. Two patients showed skin irritations and localized pain at the IPG site. Both patients underwent surgery to replant the IPG. No infections were seen in any of the eight patients enrolled. CONCLUSIONS: In this prospective cohort of surgery naïve patients, we were able to show good efficacy of HF-SCS with mean NRS reductions of 4.13 and 6.2 for back and leg pain, respectively, after a mean follow-up of 10 months.

The Polyanalgesic Consensus Conference (PACC): Recommendations for Intrathecal Drug Delivery: Guidance for Improving Safety and Mitigating Risks.

INTRODUCTION: Intrathecal therapy is an important part of the pain treatment algorithm for chronic disease states. The use of this option is a viable treatment strategy, but it is inherent for pain physicians to understand risk assessment and mitigation. In this manuscript, we explore evidence and mitigating strategies to improve safety with intrathecal therapy. METHODS: A robust literature search was performed covering January 2011 to October 9, 2016, in PubMed, Embase, MEDLINE, Biomed Central, Google Scholar, Current Contents Connect, and International Pharmaceutical Abstracts. The information was cross-referenced and compiled for evidence, analysis, and consensus review, with the intent to offer weighted recommendations and consensus statements on safety for targeted intrathecal therapy delivery. RESULTS: The Polyanalgesic Consensus Conference has made several best practice recommendations to improve care and reduce morbidity and mortality associated with intrathecal therapy through all phases of management. The United States Prevention Service Task Force evidence level and consensus strength assessments are offered for each recommendation. CONCLUSION: Intrathecal therapy is a viable and relatively safe option for the treatment of cancer- and noncancer-related pain. Continued research and expert opinion are required to improve our current pharmacokinetic and pharmacodynamic model of intrathecal drug delivery, as this will undoubtedly improve safety and efficacy.

Dorsal Root Ganglion (DRG) Stimulation in the Treatment of Phantom Limb Pain (PLP).

OBJECTIVES: Phantom limb pain (PLP) is a neuropathic condition in which pain is perceived as arising from an amputated limb. PLP is distinct from, although associated with, pain in the residual limb and nonpainful phantom sensations of the missing limb. Its treatment is extremely challenging; pharmaceutical options, while commonly employed, may be insufficient or intolerable. Neuromodulatory interventions such as spinal cord stimulation have generated mixed results and may be limited by poor somatotopic specificity. It was theorized that dorsal root ganglion (DRG) neuromodulation may be more effective. MATERIALS AND METHODS: Patients trialed a DRG neurostimulation system for their PLP and were subsequently implanted if results were positive. Retrospective chart review was completed, including pain ratings on a 100-mm visual analogue scale (VAS) and patient-reported outcomes. RESULTS: Across eight patients, the average baseline pain rating was 85.5 mm. At follow-up (mean of 14.4 months), pain was rated at 43.5 mm. Subjective ratings of quality of life and functional capacity improved. Some patients reduced or eliminated pain medications. Patients reported precise concordance of the paresthesia with painful regions, including in their phantom limbs; in one case, stimulation eliminated PLP as well as nonpainful phantom sensations. Three patients experienced a diminution of pain relief, despite good initial outcomes. CONCLUSIONS: DRG neuromodulation may be an effective tool in treating this pain etiology. Clinical outcomes in this report support recent converging evidence suggesting that the DRG may be the site of PLP generation and/or maintenance. Further research is warranted to elucidate mechanisms and optimal treatment pathways.

Spinal cord stimulation of the dorsal root ganglion for groin pain-a retrospective review.

BACKGROUND: Spinal cord stimulation (SCS) is a standard treatment option for chronic neuropathic pain. However, some anatomical pain distributions are known to be difficult to cover with traditional SCS-induced paresthesias and/or may also induce additional, unwanted stimulation. We present the results from a retrospective review of data from patients with groin pain of various etiologies treated using neuromodulation of the dorsal root ganglion (DRG). METHODS: Data from 29 patients with neuropathic groin pain were reviewed. Patients underwent trial therapy where specifically designed leads were implanted at the target DRGs between T12 and L4. Patients who had a successful trial (> 50% improvement) received the fully implantable neuromodulation system. Pain scores were captured on a visual analog scale (VAS) at baseline and at regular follow-up visits. RESULTS: Twenty-five patients (86.2%) received fully implantable neurostimulators, and the average follow-up period was 27.8 ± 4.3 (standard error of the mean, SEM) weeks. The average pain reduction was 71.4 ± 5.6%, and 82.6% (19/23) of patients experienced a > 50% reduction in their pain at the latest follow-up. Individual cases showed improvement with a variety of etiologies and pain distributions; a subanalysis of postherniorrhaphy cohort also showed significant improvement. CONCLUSIONS: Early findings suggest that neuromodulation of the DRG may be an effective treatment for chronic neuropathic pain conditions in the groin region. This technique offers a useful alternative for pain conditions that do not always respond optimally to traditional SCS therapy. Neuromodulation of the DRG provided excellent cross-dermatomal paresthesia coverage, even in cases with patients with discrete pain areas. The therapy can be specific, sustained, and independent of body position.

A prospective, randomised, double-blind, placebo-controlled study to examine the effectiveness of burst spinal cord stimulation patterns for the treatment of failed back surgery syndrome.

OBJECTIVES: Spinal cord stimulation (SCS) for the treatment of chronic pain is a well-established therapy. However, the requirement that paresthesia be continually felt by the patient has important downsides. This study evaluated the effectiveness of a new paresthesia-free SCS paradigm, called burst stimulation, for the treatment of failed back surgery syndrome (FBSS) with a prospective, randomized, double-blind, placebo-controlled design. MATERIALS AND METHODS: Twenty patients with FBSS and a preexisting SCS system each received three treatment allocations in random order for a period of one week: 500-Hz tonic stimulation, burst stimulation, and placebo stimulation. The primary outcome measure was pain intensity measured on a numerical rating scale (NRS). Secondary outcome measures were pain quality measured using the Short-Form McGill Pain Questionnaire (SFMPQ) and safety. Additional data were collected relating to pain-related disability measured using the Oswestry Disability Index (ODI). RESULTS: The lowest mean NRS and SFMPQ scores were observed under burst stimulation. For the burst stimulation treatment group, mean NRS and SFMPQ scores were significantly decreased compared with the other treatment groups. Mean NRS and SFMPQ scores were not significantly different between 500-Hz tonic stimulation and placebo stimulation. Although the lowest mean ODI score was observed under burst stimulation, no significant differences were found between the ODI categories. No adverse events occurred, and burst stimulation was significantly preferred by 16 patients (80%). CONCLUSIONS: Overall, burst stimulation resulted in significantly better pain relief and improved pain quality in the short term compared with 500-Hz tonic stimulation and placebo stimulation and was preferred by the majority of patients.

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.

Paddle versus cylindrical leads for percutaneous implantation in spinal cord stimulation for failed back surgery syndrome: a single-center trial.

OBJECTIVE: Spinal cord stimulation is an interventional treatment for chronic pain syndromes such as failed back surgery syndrome (FBSS), and it utilizes either cylindrical or paddle electrodes placed percutaneously into the epidural space. This prospective nonrandomized single-center study investigated the specific advantages and disadvantages of percutaneously implanted paddle and cylindrical leads in patients with FBSS. METHODS: Over a 2-year period, 100 patients with FBSS (43 men; 57 women; mean age: 56.3 years) were included. Paddle leads were placed percutaneously under local anesthesia in 50 patients; conventional percutaneous cylindrical lead implantation was performed in the other 50 patients (one lead permitted per patient). Follow-up included the Visual Analog Scale (VAS) assessment of pain and administration of the Oswestry Disability Questionnaire. RESULTS: Similar significant pain reduction (69%) was demonstrated in both groups (VAS pre/post: paddle: 8.8/3.7; cylindrical: 8.5/3.8). Using the same perioperative protocol for each group, we observed higher dislocation and infection rates for the cylindrical group (14% and 10%, respectively) than for the paddle group (6% and 2%, respectively). CONCLUSION: Minimally invasive percutaneous paddle and cylindrical leads are safe and effective, have low complication rates, and perform well in patients with FBSS. Both devices can be implanted using a local anesthetic, so that intraoperative and reproducible testing stimulation can be performed for sufficient paresthesia overlap prior to permanent device fixation.

Pseudoradicular and radicular low-back pain--a disease continuum rather than different entities? Answers from quantitative sensory testing.

To assess whether pseudoradicular low-back pain may be associated with subclinical sensory deficits in the distal extremity, we applied the quantitative sensory testing protocol of the German Research Network on Neuropathic Pain (DFNS) in 15 patients with pseudoradicular pain distribution. Sixteen age- and gender-matched healthy control subjects as well as 12 patients with radicular pain syndromes (L4-S1) were studied with the same protocol. Radicular pain was diagnosed using clinical criteria (pain radiation beyond the knee, motor-, sensory-, or reflex deficits, positive Laségue's test). Z-score QST profiles revealed a selective loss of vibration detection, detection of v. Frey hair contact, and cold detection in the affected dermatomes in the radicular pain group. The contralateral dermatome was also affected, but to a lesser degree. In patients with pseudoradicular pain, the sensory profile was similar, but sensory loss was less pronounced than in the radicular pain patients. There was no significant difference between the two patient groups. Vibration detection was the most sensitive parameter with 73% abnormal values in radicular and 47% in pseudoradicular cases. These data verified the sensitivity of QST to detect sensory loss in radicular compression syndromes, and support a neuropathic component in low-back pain with radiculopathy. In contrast to some central pain syndromes this sensory loss involved predominantly large fiber functions. The subclinical sensory loss in pseudoradicular cases suggests that these patients may also have a neuropathic component of their chronic pain. The spatial incongruence of pain and sensory loss in pseudoradicular pain, however, may also indicate that the two are not causally related.