Hydrogel Augmentation of the Lumbar Intervertebral Disc: An Early Feasibility Study of a Treatment for Discogenic Low Back Pain.

PURPOSE: To assess the safety and effectiveness of intradiscal hydrogel in patients with chronic low back pain (CLBP) due to degenerative disc disease (DDD) refractory to conventional medical management. MATERIALS AND METHODS: Twenty patients aged 22-69 years with numerical rating scale (NRS) pain of ≥4 were enrolled. All patients with CLBP resulting from DDD confirmed by imaging and discography received injections of hydrogel (Hydrafil Intervertebral Disc Augmentation; ReGelTec, Baltimore, Maryland) at 1 or 2 lumbar levels (29 levels treated) from August to December 2020. The primary safety end point was freedom from serious adverse events (SAEs). The primary performance end point was successful gel delivery into the desired disc. Patients were also assessed on the NRS as well as the Oswestry disability index (ODI). RESULTS: Nineteen patients were followed up at a mean of 131 days, and 1 patient was lost to follow-up. Preliminary results showed significant reductions in median NRS back pain from 7 (range 4-10) to 1 (range 0-8) (P <.0001) and median ODI scores from 54 (range 22-58) to 2 (range 0-58) (P <.0001) at 6 months of follow-up. There were 5 SAEs, and 4 of the 2 were determined to be associated with treatment. CONCLUSIONS: This early feasibility study showed that the hydrogel implant was safe with no persistently symptomatic SAEs, and demonstrated effectiveness with significant reduction in pain and improvement in function when used to treat painful DDD and CLBP.

Defining the Boundaries of Patient Perception in Spinal Cord Stimulation Programming.

OBJECTIVES: Recent developments in spinal cord stimulation (SCS) programming have initiated new modalities of imperceptible stimulation. However, the boundaries of sensory perception are not well defined. The BEnchtop NEuromodulation Following endIng of Trial study aimed to create a map of perceptual threshold responses across a broad range of SCS parameters and programming to inform subperception therapy design. MATERIALS AND METHODS: This multicenter study was conducted at seven US sites. A total of 43 patients with low back and/or leg pain who completed a percutaneous commercial SCS trial were enrolled. Test stimulation was delivered through trial leads for approximately 90 minutes before removal. SCS parameters, including amplitude, frequency, pulse width (PW), electrode configuration, cycling, and multifrequency stimulation were varied during testing. Paresthesia threshold (PT), comfort level (CL), perceptual coverage area, and paresthesia quality (through patient selection of keywords) were collected. Differences were evaluated with analysis of variance followed by post hoc multiple comparisons using t-tests with Bonferroni correction. RESULTS: PT was primarily determined by PW and was insensitive to frequency for constant frequency stimulation (range: 20 Hz-10 kHz; F(1284) = 69.58, p < 0.0001). For all tests, CL was approximately 25% higher than PT. The dominant variable that influenced paresthesia quality was frequency. Sensations described as comfortable and tingling were most common for frequencies between 60 Hz and 2.4 kHz; unpleasant sensations were generally more common outside this range. Increasing distance between active electrodes from 7 mm to 14 mm, or cycling the SCS waveform at 1 Hz, decreased PT (p < 0.0001). Finally, PT for a low-frequency stimulus (ie, 60 Hz) was unaffected by mixing with a sub-PT high-frequency stimulus. CONCLUSIONS: In contrast to previous work investigating narrower ranges, PW primarily influenced PT, independently of frequency. Paresthesia quality was primarily influenced by pulse frequency. These findings advance our understanding of SCS therapy and may be used to improve future novel neuromodulation paradigms.

Remote Management of Spinal Cord Stimulation Devices for Chronic Pain: Expert Recommendations on Best Practices for Proper Utilization and Future Considerations.

OBJECTIVE: Emerging spinal cord stimulation (SCS) remote monitoring and programming technologies provide a unique opportunity to address challenges of in-person visits and improve patient care, although clinical guidance on implementation is needed. The goal of this document is to establish best clinical practices for integration of remote device management into the care of patients with SCS, including remote monitoring and remote programming. MATERIALS AND METHODS: A panel of experts in SCS met in July 2022, and additional experts contributed to the development of recommendations after the meeting via survey responses and correspondence. RESULTS: Major goals of remote SCS device management were identified, including prompt identification and resolution of SCS-related issues. The panel identified metrics for remote monitoring and classified them into three categories: device-related (eg, stimulation usage); measurable physiologic or disease-related (eg, patient physical activity or pedometry); and patient-reported (eg, sleep quality and pain intensity). Recommendations were made for frequency of reviewing remote monitoring metrics, although providers should tailor follow-up to individual patient needs. Such periodic reviews of remote monitoring metrics would occur separately from automatic monitoring system notifications (if key metrics fall outside an acceptable range). The guidelines were developed in consideration of reimbursement processes, privacy concerns, and the responsibilities of the care team, industry professionals, manufacturers, patients, and caregivers. Both existing and needed clinical evidence were covered, including outcomes of interest for future studies. CONCLUSIONS: Given the expansion of SCS device capabilities, this document provides critical guidance on best practices for using remote device management, although medical necessity should drive all remote monitoring decisions, with individualized patient care. The authors also describe the potential of these emerging technologies to improve outcomes for patients with SCS, although more clinical evidence is needed.

Multiphase Spinal Cord Stimulation in Participants With Chronic Back or Leg Pain: Results of the BENEFIT-02 Randomized Clinical Trial.

OBJECTIVE: This study aimed to assess the safety and effectiveness of a new charge-distributed multiphase stimulation paradigm during an extended spinal cord stimulation (SCS) trial. MATERIALS AND METHODS: This prospective, multicenter, randomized, single-blind, feasibility study included participants with chronic low back and/or leg pain and baseline numerical rating scale (NRS) for overall pain intensity ≥6. After a successful commercial SCS trial, participants were randomized to multiphase SCS therapy A (approximately 600-1500 Hz) or B (approximately 300-600 Hz), delivered via an investigational external pulse generator and existing leads during an 11-to-12-day testing period. Primary end points were mean NRS change from baseline to final in-office visit for each multiphase therapy and between therapies. Secondary end points included mean NRS change from end of commercial trial to final study visit and incidence of device-related adverse events (AEs). Additional measures included patient-reported outcomes collected at home through electronic watches and written diaries. Power usage was compared between multiphase and commercial therapies. RESULTS: A total of 122 participants initiated a commercial trial; 77 were randomized to a multiphase arm, and 65 completed the study. Reductions in mean NRS scores from baseline to final study visit were significant for multiphase therapy A and B (-4.3 and -4.7, respectively; both p < 0.0001). There was no statistically significant difference in mean NRS reduction or percent pain relief between multiphase therapies. In an additional analysis, 63.9% of participants reported greater pain relief with multiphase than with commercial SCS therapy in the at-home setting. On average, multiphase required less power than did commercial devices. One non-serious device-related AE was reported, and no infections occurred during the extended trial. CONCLUSIONS: Multiphase SCS effectively reduced pain in participants with chronic low back and/or leg pain during a trial, with no unanticipated device-related AEs reported. Future studies should evaluate long-term effectiveness of multiphase stimulation. CLINICAL TRIAL REGISTRATION: The Clinicaltrials.gov registration number for the study is NCT03594266.

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.

Novel spinal cord stimulation system with a Battery-Free micro-implantable pulse generator.

Spinal cord stimulation (SCS) is effective for the treatment of chronic intractable pain of the trunk and limbs. The mechanism of action may be based, at least in part, upon the gate control theory; however, new waveforms may suggest other mechanisms. Although benefits of the SCS technology generally outweigh the complications associated with SCS, some complications such as infection and skin erosion over the implant can result in device removal. Additional reasons for device removal, such as pocket pain and battery depletion, have driven technological innovations including battery-free implants and device miniaturization. The neurostimulation system described here was specifically designed to address complications commonly associated with implantable batteries and/or larger implantable devices. The benefits of the small size are further augmented by a minimally invasive implant procedure. Usability data show that patients found this novel neurostimulation system to be easy to use and comfortable to wear. What is more, clinical data demonstrate that the use of this system provides statistically significant reduction in pain scores with responder rates (defined as ≥50% reduction in pain) of 78% in the low back and 83% in the leg(s). Advances in miniaturization technology arose from the considerable shrinkage of the integrated circuit, with an increase in performance, according to Moore's law (1965). However, commensurate improvements in battery technology have not maintained a similar pace. This has prompted some manufacturers to place the battery outside, against the skin, thereby allowing a massive reduction in the implant volume, with the hopes of fewer device-related complications.

Treatment of chronic axial back pain with 60-day percutaneous medial branch PNS: Primary end point results from a prospective, multicenter study.

BACKGROUND: The objective of this prospective, multicenter study is to characterize responses to percutaneous medial branch peripheral nerve stimulation (PNS) to determine if results from earlier, smaller single-center studies and reports were generalizable when performed at a larger number and wider variety of centers in patients recalcitrant to nonsurgical treatments. MATERIALS & METHODS: Participants with chronic axial low back pain (LBP) were implanted with percutaneous PNS leads targeting the lumbar medial branch nerves for up to 60 days, after which the leads were removed. Participants were followed long-term for 12 months after the 2-month PNS treatment. Data collection is complete for visits through end of treatment with PNS (primary end point) and 6 months after lead removal (8 months after start of treatment), with some participant follow-up visits thereafter in progress. RESULTS: Clinically and statistically significant reductions in pain intensity, disability, and pain interference were reported by a majority of participants. Seventy-three percent of participants were successes for the primary end point, reporting clinically significant (≥30%) reductions in back pain intensity after the 2-month percutaneous PNS treatment (n = 54/74). Whereas prospective follow-up is ongoing, among those who had already completed the long-term follow-up visits (n = 51), reductions in pain intensity, disability, and pain interference were sustained in a majority of participants through 14 months after the start of treatment. CONCLUSION: Given the minimally invasive, nondestructive nature of percutaneous PNS and the significant benefits experienced by participants who were recalcitrant to nonsurgical treatments, percutaneous PNS may provide a promising first-line neurostimulation treatment option for patients with chronic axial back pain.

Emergence From the COVID-19 Pandemic and the Care of Chronic Pain: Guidance for the Interventionalist.

BACKGROUND: The current coronavirus disease 2019 (COVID-19) pandemic led to a significant disruption in the care of pain from chronic and subacute conditions. The impact of this cessation of pain treatment may have unintended consequences of increased pain, reduced function, increased reliance on opioid medications, and potential increased morbidity, due to the systemic impact of untreated disease burden. This may include decreased mobility, reduction in overall health status, and increase of opioid use with the associated risks. METHODS: The article is the study of the American Society of Pain and Neuroscience (ASPN) COVID-19 task force to evaluate the policies set forth by federal, state, and local agencies to reduce or eliminate elective procedures for those patients with pain from spine, nerve, and joint disease. The impact of these decisions, which were needed to reduce the spread of the pandemic, led to a delay in care for many patients. We hence review an emergence plan to reinitiate this pain-related care. The goal is to outline a path to work with federal, state, and local authorities to combat the spread of the pandemic and minimize the deleterious impact of pain and suffering on our chronic pain patients. RESULTS: The article sets forth a strategy for the interventional pain centers to reemerge from the current pandemic and to set a course for future events. CONCLUSIONS: The COVID-19 pandemic represents an overwhelming challenge to interventional pain physicians and their patients. In addition to urgent actions needed for disease mitigation, the ASPN recommends a staged return to pain management professionals' workflow.

A Systematic Literature Review of Peripheral Nerve Stimulation Therapies for the Treatment of Pain.

OBJECTIVE: To conduct a systematic literature review of peripheral nerve stimulation (PNS) for pain. DESIGN: Grade the evidence for PNS. METHODS: An international interdisciplinary work group conducted a literature search for PNS. Abstracts were reviewed to select studies for grading. Inclusion/exclusion criteria included prospective randomized controlled trials (RCTs) with meaningful clinical outcomes that were not part of a larger or previously reported group. Excluded studies were retrospective, had less than two months of follow-up, or existed only as abstracts. Full studies were graded by two independent reviewers using the modified Interventional Pain Management Techniques-Quality Appraisal of Reliability and Risk of Bias Assessment, the Cochrane Collaborations Risk of Bias assessment, and the US Preventative Services Task Force level-of-evidence criteria. RESULTS: Peripheral nerve stimulation was studied in 14 RCTs for a variety of painful conditions (headache, shoulder, pelvic, back, extremity, and trunk pain). Moderate to strong evidence supported the use of PNS to treat pain. CONCLUSION: Peripheral nerve stimulation has moderate/strong evidence. Additional prospective trials could further refine appropriate populations and pain diagnoses.

A Systematic Literature Review of Dorsal Root Ganglion Neurostimulation for the Treatment of Pain.

OBJECTIVE: To conduct a systematic literature review of dorsal root ganglion (DRG) stimulation for pain. DESIGN: Grade the evidence for DRG stimulation. METHODS: An international, interdisciplinary work group conducted a literature search for DRG stimulation. Abstracts were reviewed to select studies for grading. General inclusion criteria were prospective trials (randomized controlled trials and observational studies) that were not part of a larger or previously reported group. Excluded studies were retrospective, too small, or existed only as abstracts. Studies were graded using the modified Interventional Pain Management Techniques-Quality Appraisal of Reliability and Risk of Bias Assessment, the Cochrane Collaborations Risk of Bias assessment, and the US Preventative Services Task Force level-of-evidence criteria. RESULTS: DRG stimulation has Level II evidence (moderate) based upon one high-quality pivotal randomized controlled trial and two lower-quality studies. CONCLUSIONS: Moderate-level evidence supports DRG stimulation for treating chronic focal neuropathic pain and complex regional pain syndrome.

A Systematic Literature Review of Spine Neurostimulation Therapies for the Treatment of Pain.

OBJECTIVE: To conduct a systematic literature review of spinal cord stimulation (SCS) for pain. DESIGN: Grade the evidence for SCS. METHODS: An international, interdisciplinary work group conducted literature searches, reviewed abstracts, and selected studies for grading. Inclusion/exclusion criteria included randomized controlled trials (RCTs) of patients with intractable pain of greater than one year's duration. Full studies were graded by two independent reviewers. Excluded studies were retrospective, had small numbers of subjects, or existed only as abstracts. Studies were graded using the modified Interventional Pain Management Techniques-Quality Appraisal of Reliability and Risk of Bias Assessment, the Cochrane Collaborations Risk of Bias assessment, and the US Preventative Services Task Force level-of-evidence criteria. RESULTS: SCS has Level 1 evidence (strong) for axial back/lumbar radiculopathy or neuralgia (five high-quality RCTs) and complex regional pain syndrome (one high-quality RCT). CONCLUSIONS: High-level evidence supports SCS for treating chronic pain and complex regional pain syndrome. For patients with failed back surgery syndrome, SCS was more effective than reoperation or medical management. New stimulation waveforms and frequencies may provide a greater likelihood of pain relief compared with conventional SCS for patients with axial back pain, with or without radicular pain.

A Comprehensive Practice Guideline for Magnetic Resonance Imaging Compatibility in Implanted Neuromodulation Devices.

OBJECTIVES: The evolution of neuromodulation devices in order to enter magnetic resonance imaging (MRI) scanners has been one of understanding limitations, engineering modifications, and the development of a consensus within the community in which the FDA could safely administer labeling for the devices. In the initial decades of neuromodulation, it has been contraindicated for MRI use with implanted devices. In this review, we take a comprehensive approach to address all the major products currently on the market in order to provide physicians with the ability to determine when an MRI can be performed for each type of device implant. MATERIALS AND METHODS: We have prepared a narrative review of MRI guidelines for currently marketed implanted neuromodulation devices including spinal cord stimulators, intrathecal drug delivery systems, peripheral nerve stimulators, deep brain stimulators, vagal nerve stimulators, and sacral nerve stimulators. Data sources included relevant literature identified through searches of PubMed, MEDLINE/OVID, SCOPUS, and manual searches of the bibliographies of known primary and review articles, as well as manufacturer-provided information. RESULTS: Guidelines and recommendations for each device and their respective guidelines for use in and around MR environments are presented. CONCLUSIONS: This is the first comprehensive guideline with regards to various devices in the market and MRI compatibility from the American Society of Pain and Neuroscience.

Paresthesia-Free Dorsal Root Ganglion Stimulation: An ACCURATE Study Sub-Analysis.

INTRODUCTION: ACCURATE, a randomized controlled trial comparing dorsal root ganglion (DRG) stimulation to spinal cord stimulation, showed that DRG stimulation is a safe and effective therapy in individuals with lower extremity chronic pain due to complex regional pain syndrome (CRPS) type I or II. Investigators noted that DRG stimulation programming could be adjusted to minimize, or eliminate, the feeling of paresthesia while maintaining adequate pain relief. The present study explores treatment outcomes for DRG subjects who were paresthesia-free vs. those who experienced the sensation of paresthesia, as well as the factors that predicted paresthesia-free analgesia. METHODS: A retrospective analysis of therapy outcomes was conducted for 61 subjects in the ACCURATE study who received a permanent DRG neurostimulator. Outcomes of subjects who were paresthesia-free were compared to those who experienced paresthesia-present therapy at 1, 3, 6, 9, and 12-month follow-ups. Predictor variables for the presence or absence of paresthesias with DRG stimulation were also explored. RESULTS: The percentage of subjects with paresthesia-free pain relief increased from 16.4% at 1-month to 38.3% at 12-months. Paresthesia-free subjects generally had similar or better outcomes for pain severity, pain interference, quality of life, and mood state as subjects with paresthesia-present stimulation. Factors that increased the odds of a subject feeling paresthesia were higher stimulation amplitudes and frequencies, number of implanted leads, and younger age. CONCLUSIONS: Some DRG subjects achieved effective paresthesia-free analgesia in the ACCURATE trial. This supports the observation that paresthesia is not synonymous with pain relief or required for optimal analgesia with DRG stimulation.

Multicenter, Randomized, Double-Blind Study Protocol Using Human Spinal Cord Recording Comparing Safety, Efficacy, and Neurophysiological Responses Between Patients Being Treated With Evoked Compound Action Potential-Controlled Closed-Loop Spinal Cord Stimulation or Open-Loop Spinal Cord Stimulation (the Evoke Study).

BACKGROUND: The spinal cord (SC) response to stimulation has yet to be studied in a pivotal clinical study. We report the study design of an ongoing multicenter, randomized, double-blind, controlled, parallel-arm study of an evoked compound action potential (ECAP) controlled closed-loop spinal cord stimulation (SCS) system, which aims to gain U.S. Food and Drug Administration approval. METHODS: This study will enroll 134 SCS candidates with chronic trunk and limb pain from up to 20 United States sites. Subjects are randomized 1:1 to receive ECAP-controlled closed-loop or open-loop, conventional SCS. The primary objective is noninferiority of closed-loop stimulation determined by the proportion of subjects with ≥50% reduction in overall trunk and limb pain and no increase in pain medications at the three-month visit. If noninferiority is met, superiority is tested. In addition, measures recommended by IMMPACT (e.g., pain intensity, functional disability, emotional functioning, quality of life, impression of change, and sleep), neurophysiological properties (e.g., SC activation, conduction velocity, chronaxie, and rheobase), and safety are analyzed. DISCUSSION: All approved SCS therapies, regardless of the presence or absence of stimulation induced paresthesias, produce fixed-output stimuli; that is, the energy delivered from the electrode array has a defined output irrespective of the neural response of SC fibers. An SCS system has been developed that directly measures the neurophysiologic activation of the SC to stimulation (i.e., ECAP amplitude) and uses this information in a feedback mechanism to produce closed-loop SCS to maintain optimal and stable activation of the SC. This study represents the first randomized, double-blind, pivotal study in the field of neuromodulation to measure SC activation in ECAP-controlled closed-loop versus open-loop stimulation and is expected to yield important information regarding differences in safety, efficacy, and neurophysiological properties. The potential clinical utility of these objective measurements of SC activation and other neurophysiological properties promises to improve outcomes of SCS for chronic pain patients.

Comparison of Paresthesia Coverage of Patient's Pain: Dorsal Root Ganglion vs. Spinal Cord Stimulation. An ACCURATE Study Sub-Analysis.

OBJECTIVES: This was a sub-analysis of the ACCURATE clinical trial that evaluated the accuracy and necessity of targeting paresthesia coverage of painful areas with dorsal root ganglion (DRG) stimulation vs. tonic spinal cord stimulation (SCS). MATERIALS AND METHODS: On diagrams of the torso and lower limbs, subjects marked where they felt pain at baseline and paresthesias at three months postimplant. Seventy-five subjects (41 DRG and 34 SCS) with diagrams of sufficient quality were scanned, digitized, and included in this analysis. Subject completed diagrams were digitized and superimposed with a grid of 1398 squares. Quantification of the percentage of bodily areas affected by pain and stimulation induced paresthesias was performed. RESULTS: The percent of painful areas covered by paresthesia was significantly lower for DRG subjects than for SCS subjects (13% vs. 28% of the painful regions, p < 0.05), possibly because significantly more DRG subjects felt no paresthesia during stimulation when compared to SCS subjects (13/41 DRG vs. 3/34 SCS) (p < 0.05). The amount of paresthesia produced outside the painful areas (unrequired paresthesia) was significantly lower in DRG subjects than that of SCS subjects. On average, the percent of unrequired paresthesia was only 20% of the subjects' total painful body surface area in the DRG group compared to 210% in the SCS group (p < 0.01). CONCLUSIONS: The results of this ACCURATE study sub-analysis show that DRG stimulation produces paresthesias, on average, that are less frequent, less intense, with a smaller footprint on the body and less dependent on positional changes.

Long-term quality of life improvement for chronic intractable back and leg pain patients using spinal cord stimulation: 12-month results from the SENZA-RCT.

PURPOSE: Chronic axial low-back pain is a debilitating disorder that impacts all aspects of an afflicted individual's life. Effective, durable treatments have historically been elusive. Interventional therapies, such as spinal cord stimulation (SCS), have shown limited efficacy at best. Recently, a novel treatment, 10 kHz SCS, has demonstrated superior pain relief compared with traditional SCS in a randomized controlled trial (RCT). In this manuscript, we report on the long-term improvements in quality of life (QoL) outcomes for subjects enrolled in this study. METHODS: A prospective, multicenter, randomized controlled trial (SENZA-RCT) was conducted. Patients with both chronic back and leg pain were enrolled and randomized (1:1) into 10 kHz SCS or traditional SCS treatment groups. A total of 171 subjects received a permanent SCS device implant. QoL and functionality measures were collected up to 12 months. The device remote control utilization, which is an indication of patient interaction with the device for adjustments, was collected at 24-month post-implantation. RESULTS: At 12 months, a higher proportion of 10 kHz SCS subjects had marked improvement of their disability (Oswestry Disability Index) to a "moderate" or "minimal" impact on their daily function versus the control group. The subjects also reported better improvement in the Global Assessment of Functioning, Clinician Global Impression of Change, Pittsburgh Sleep Quality Index, and short-form McGill Pain Questionnaire, compared to traditional SCS subjects. The 10 kHz SCS subjects also reported far higher rates of both driving and sleeping with their device turned on, as well as reduced reliance on their programmers to adjust therapy settings. CONCLUSIONS: In addition to superior pain relief, 10 kHz SCS provides long-term improvements in quality of life and functionality for subjects with chronic low-back and leg pain. TRIAL REGISTRATION: ClinicalTrials.gov (NCT01609972).

Success Using Neuromodulation With BURST (SUNBURST) Study: Results From a Prospective, Randomized Controlled Trial Using a Novel Burst Waveform.

OBJECTIVE: The purpose of the multicenter, randomized, unblinded, crossover Success Using Neuromodulation with BURST (SUNBURST) study was to determine the safety and efficacy of a device delivering both traditional tonic stimulation and burst stimulation to patients with chronic pain of the trunk and/or limbs. METHODS: Following a successful tonic trial, 100 subjects were randomized to receive one stimulation mode for the first 12 weeks, and then the other stimulation mode for the next 12 weeks. The primary endpoint assessed the noninferiority of the within-subject difference between tonic and burst for the mean daily overall VAS score. An intention-to-treat analysis was conducted using data at the 12- and 24-week visits. Subjects then used the stimulation mode of their choice and were followed for one year. Descriptive statistics were used analyze additional endpoints and to characterize the safety profile of the device. RESULTS: The SUNBURST study demonstrated that burst stimulation is noninferior to tonic stimulation (p < 0.001). Superiority of burst was also achieved (p < 0.017). Significantly more subjects (70.8%) preferred burst stimulation over tonic stimulation (p < 0.001). Preference was sustained through one year: 68.2% of subjects preferred burst stimulation, 23.9% of subjects preferred tonic, and 8.0% of subjects had no preference. No unanticipated adverse events were reported and the safety profile was similar to other spinal cord stimulation studies. CONCLUSIONS: The SUNBURST study demonstrated that burst spinal cord stimulation is safe and effective. Burst stimulation was not only noninferior but also superior to tonic stimulation for the treatment of chronic pain. A multimodal stimulation device has advantages.

Multicenter Retrospective Study of Neurostimulation With Exit of Therapy by Explant.

INTRODUCTION: Spinal cord stimulation (SCS) devices are cost effective and improve function as well as quality of life. Despite the demonstrated benefits of SCS, some patients have the device explanted. We are interested in exploring the patient characteristics of those explanted. METHODS: This is a retrospective chart review of neurostimulation patients who underwent explantation at 18 centers across the United States within the previous five years. RESULTS: Data from 352 patients were collected and compiled. Failed Back Surgery syndrome was the most common diagnosis (38.9%; n = 136/350) and over half of the patients reported numerical rating scale (NRS) scores ≥8 prior to implant (64.3%; n = 207/322). All patients reported changes in NRS scores across time, with an initial decrease after implant followed by a pre-explant increase (F (2, 961) = 121.7, p < 0.001). The most common reason for device explant was lack or loss of efficacy (43.9%; 152/346) followed by complications (20.2%; 70/346). Eighteen percent (18%; 62/343) of patients were explanted by a different physician than the implanting one. Rechargeable devices were explanted at a median of 15 months, whereas primary cell device explants occurred at a median of 36 months (CI 01.434, 2.373; median endpoint time ratio = 2.40). DISCUSSION: Loss or lack of efficacy and complications with therapy represent the most frequent reasons for neurostimulation explantation. Of the devices that were explanted, therapy was terminated earlier when devices were rechargeable, when complications occurred, or when pain relief was not achieved or maintained. Furthermore, in nearly 20% of the cases, a different provider than the implanting physician performed device removal. CONCLUSIONS: SCS is largely a safe and efficacious strategy for treating select chronic refractory pain syndromes. Further prospective data and innovation are needed to improve patient selection, maintain SCS therapeutic efficacy and reduce the reasons that lead to device explant.

Novel 10-kHz High-frequency Therapy (HF10 Therapy) Is Superior to Traditional Low-frequency Spinal Cord Stimulation for the Treatment of Chronic Back and Leg Pain: The SENZA-RCT Randomized Controlled Trial.

BACKGROUND: Current treatments for chronic pain have limited effectiveness and commonly known side effects. Given the prevalence and burden of intractable pain, additional therapeutic approaches are desired. Spinal cord stimulation (SCS) delivered at 10 kHz (as in HF10 therapy) may provide pain relief without the paresthesias typical of traditional low-frequency SCS. The objective of this randomized, parallel-arm, noninferiority study was to compare long-term safety and efficacy of SCS therapies in patients with back and leg pain. METHODS: A total of 198 subjects with both back and leg pain were randomized in a 1:1 ratio to a treatment group across 10 comprehensive pain treatment centers. Of these, 171 passed a temporary trial and were implanted with an SCS system. Responders (the primary outcome) were defined as having 50% or greater back pain reduction with no stimulation-related neurological deficit. RESULTS: At 3 months, 84.5% of implanted HF10 therapy subjects were responders for back pain and 83.1% for leg pain, and 43.8% of traditional SCS subjects were responders for back pain and 55.5% for leg pain (P < 0.001 for both back and leg pain comparisons). The relative ratio for responders was 1.9 (95% CI, 1.4 to 2.5) for back pain and 1.5 (95% CI, 1.2 to 1.9) for leg pain. The superiority of HF10 therapy over traditional SCS for leg and back pain was sustained through 12 months (P < 0.001). HF10 therapy subjects did not experience paresthesias. CONCLUSION: HF10 therapy promises to substantially impact the management of back and leg pain with broad applicability to patients, physicians, and payers.