Project description:INTRODUCTION:Kilohertz frequency spinal cord stimulation (kHz-SCS) deposits significantly more power in tissue compared to SCS at conventional frequencies, reflecting increased duty cycle (pulse compression). We hypothesize kHz-SCS increases local tissue temperature by joule heat, which may influence the clinical outcomes. METHODS:To establish the role of tissue heating in KHZ-SCS, a decisive first step is to characterize the range of temperature changes expected during conventional and KHZ-SCS protocols. Fiber optic probes quantified temperature increases around an experimental SCS lead in a bath phantom. These data were used to verify a SCS lead heat-transfer model based on joule heat. Temperature increases were then predicted in a seven-compartment (soft tissue, vertebral bone, fat, intervertebral disc, meninges, spinal cord with nerve roots) geometric human spinal cord model under varied parameterization. RESULTS:The experimentally constrained bio-heat model shows SCS waveform power (waveform RMS) determines tissue heating at the spinal cord and surrounding tissues. For example, we predict temperature increased at dorsal spinal cord of 0.18-1.72?°C during 3.5?mA peak 10?KHz stimulation with a 40-10-40 ?s biphasic pulse pattern, 0.09-0.22?°C during 3.5?mA 1?KHz 100-100-100 ?s stimulation, and less than 0.05?°C during 3.5?mA 50?Hz 200-100-200 ?s stimulation. Notably, peak heating of the spinal cord and other tissues increases superlinearly with stimulation power and so are especially sensitive to incremental changes in SCS pulse amplitude or frequency (with associated pulse compression). Further supporting distinct SCS intervention strategies based on heating; the spatial profile of temperature changes is more uniform compared to electric fields, which suggests less sensitivity to lead position. CONCLUSIONS:Tissue heating may impact short and long-term outcomes of KHZ-SCS, and even as an adjunct mechanism, suggests distinct strategies for lead position and programming optimization.

Project description:Background and objectivesMultiple variables play a role in spinal cord stimulation (SCS) treatment outcomes, including patient anatomy, pain pattern, lead location, stimulation parameters, and so on. A wide range of stimulation parameters are considered safe and on-label, and as a result a growing number of new frequencies and frequency-combinations are being incorporated into standard practice. A standardized approach to therapy delivery may provide more consistent outcomes for more patients. The Vectors study evaluated whether there is significant sustained improvement in pain and functional outcomes when therapy is delivered using a standardized approach.Materials and methodsVectors, a post-market, single-arm study evaluated the safety and efficacy of SCS with an implantable neurostimulator starting with 1 kHz stimulation, targeting the T9-T10 disc space following paresthesia mapping. Subjects with chronic intractable low back and leg pain (visual analogue scale [VAS] ≥ 50 mm) were enrolled. The primary endpoint was change in overall pain (VAS) at the three-month visit compared to baseline. Subjects were followed through 12 months. Secondary endpoints included changes in low back and leg pain, quality of life (European Quality of Life - Five Dimensions, EQ-5D-5L), disability (Oswestry Disability Index, ODI), individual subject goals, and subject satisfaction.ResultsThere was a significant reduction in overall pain (VAS; 45.4 mm) through the three-month visit, which was sustained through 12 months. At 12 months, 79% of subjects had ≥50% improvement in at least one pain domain (overall, lowback or leg) with 85% of subjects reporting therapy satisfaction. There was a decrease in disability and an improvement in quality of life with 70% of subjects achieving a personal activity goal by the three-month visit.ConclusionsLong-term pain relief and improvement in quality of life and function were achieved when following a standardized workflow.Clinical trial registrationThe Clinicaltrials.gov registration number for the study is NCT03345472.

Project description:BACKGROUND:Pain relief with spinal cord stimulation (SCS) has focused historically on paresthesias overlapping chronically painful areas. A higher level evidence supports the use of SCS in treating leg pain than supports back pain, as it is difficult to achieve adequate paresthesia coverage, and then pain relief, in the low back region. In comparison, 10-kHz high-frequency (HF10 therapy) SCS therapy does not rely on intraoperative paresthesia mapping and remains paresthesia-free during therapy. OBJECTIVE:To compare long-term results of HF10 therapy and traditional low-frequency SCS. METHODS:A pragmatic randomized, controlled, pivotal trial with 24-month follow-up was conducted across 11 comprehensive pain treatment centers. Subjects had Visual Analog Scale scores of ?5.0/10.0 cm for both back and leg pain, and were assigned randomly (1:1) to receive HF10 therapy or low-frequency SCS. The primary end point was a responder rate, defined as ?50% back pain reduction from baseline at 3 months with a secondary end point at 12 months (previously reported). In this article, 24-month secondary results are presented. Non-inferiority was first assessed, and if demonstrated the results were tested for superiority. RESULTS:In the study, 198 subjects were randomized (101 HF10 therapy, 97 traditional SCS). One hundred seventy-one subjects (90 HF10 therapy, 81 traditional SCS) successfully completed a short-term trial and were implanted. Subjects averaged 54.9 ± 12.9 years old, 13.6 ± 11.3 years since diagnosis, 86.6% had back surgery, 88.3% were taking opioid analgesics. 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 < .001 for both back and leg pain comparisons, non-inferiority and superiority). At 24 months, more subjects were responders to HF10 therapy than traditional SCS (back pain: 76.5% vs 49.3%; 27.2% difference, 95% CI, 10.1%-41.8%; P < .001 for non-inferiority and superiority; leg pain: 72.9% vs 49.3%; 23.6% difference, 95% CI, 5.9%-38.6%; P < .001 for non-inferiority and P = .003 for superiority). Also at 24 months, back pain decreased to a greater degree with HF10 therapy (66.9% ± 31.8%) than traditional SCS (41.1% ± 36.8%, P < .001 for non-inferiority and superiority). Leg pain also decreased to a greater degree with HF10 therapy (65.1% ± 36.0%) than traditional SCS (46.0% ± 40.4%, P < .001 for non-inferiority and P = .002 for superiority). CONCLUSION:This study demonstrates long-term superiority of HF10 therapy compared with traditional SCS in treating both back and leg pain. The advantages of HF10 therapy are anticipated to impact the management of chronic pain patients substantially. ABBREVIATIONS:IPG, implantable pulse generatorMCID, minimal clinically important differencePI, permanent implantODI, Oswestry Disability IndexSCS, spinal cord stimulationVAS, Visual Analog Scale.

Project description:BackgroundSuccessful treatments for intractable chronic low back pain (CLBP) in patients who are not eligible for surgical interventions are scarce. The superior efficacy of differential target multiplexed spinal cord stimulation (DTM SCS) to conventional SCS (Conv-SCS) on the treatment of CLBP in patients with persistent spinal pain syndrome (PSPS) who have failed surgical interventions (PSPS-T2) motivated the evaluation of DTM SCS versus Conv-SCS on PSPS patients who are non-surgical candidates (PSPS-T1).MethodsThis is a prospective, open label, crossover, post-market randomized controlled trial in 20 centers across the United States. Eligible patients were randomized to either DTM SCS or Conv-SCS in a 1:1 ratio. Primary endpoint was CLBP responder rate (percentage of subjects with ≥50% CLBP relief) at 3-month in randomized subjects who completed trialing (modified intention-to-treat population). Patients were followed up to 12 months. Secondary endpoints included change of CLBP and leg pain, responder rates, changes in disability, quality of life, patient satisfaction and global impression of change, and safety profile. An optional crossover was available at 6-month to all patients.ResultsAbout 121 PSPS-T1 subjects with CLBP and leg pain mostly associated with degenerative disc disease and radiculopathy and who were not eligible for spine surgery were randomized. CLBP responder rate with DTM SCS (93.5%) was superior to Conv-SCS (36.4%) at the primary endpoint. Superior CLBP responder rates (88.1%-90.5%) were obtained with DTM SCS at all other timepoints. Mean CLBP reduction with DTM SCS (6.52 cm) was superior to that with Conv-SCS (3.01 cm) at the primary endpoint. Similar CLBP reductions (6.23-6.43 cm) were obtained with DTM SCS at other timepoints. DTM SCS provided significantly better leg pain reduction and responder rate, improvement of disability and quality of life, and better patient satisfaction and global impression of change. 90.9% of Conv-SCS subjects who crossed over were CLBP responders at completion of the study. Similar safety profiles were observed between the two groups.ConclusionDTM SCS for chronic CLBP in nonsurgical candidates is superior to Conv-SCS. Improvements were sustained and provided significant benefits on the management of these patients.

Dataset Information

Effects of Rate on Analgesia in Kilohertz Frequency Spinal Cord Stimulation: Results of the PROCO Randomized Controlled Trial.

Publications

Effects of Rate on Analgesia in Kilohertz Frequency Spinal Cord Stimulation: Results of the PROCO Randomized Controlled Trial.

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