One-Year Results of Prospective Research Study Using 10 kHz Spinal Cord Stimulation in Persistent Nonoperated Low Back Pain of Neuropathic Origin: Maiden Back Study

PurposeSpinal cord stimulation (SCS) is a recommended treatment for chronic neuropathic pain. Persistent nonoperative low back pain of neuropathic origin has profound negative impacts on patient’s lives. This prospective, open label, research study aimed to explore the use of SCS in patients with associated features of central sensitisation such as allodynia and hyperalgesia.Materials and MethodsTwenty-one patients with back pain and hyperalgesia or allodynia who had not had prior spinal surgery underwent a SCS trial followed by full implantation. SCS comprised administering electrical impulses epidurally at a frequency of 10 kHz and pulse width of 30 μsec. Patients attended follow-up visits after 6 and 12 months of SCS. Repeated measure ANOVAs/Friedman tests explored change after 6 and 12 months of 10 kHz SCS. Independent sample t-tests/Mann–Whitney U tests examined differences in response after 12 months of 10 kHz SCS.ResultsBack and leg pain, quality of life (QoL), pain-related disability, and morphine equivalence significantly improved compared with baseline following 6 and 12 months of 10 kHz SCS. There were no increases in the consumption of opioids, amitriptyline, gabapentin or pregabalin in any patient. After 12 months of treatment, 52% encountered ≥50% improvement in back pain, 44% achieved remission (0–3 cm back pain VAS), 40% reported ODI scores between 0 and 40 and 60% experienced a reduction of at least 10 ODI points. Patients reporting ≥10-point improvement in ODI had significantly longer pain history durations and experienced significantly greater improvements in back pain, leg pain and QoL than those reporting <10-point improvement in ODI.ConclusionThe 10 kHz SCS improved back and leg pain, QoL, pain-related disability and medication consumption in patients with nonoperative back pain of neuropathic origin. With further research incorporating a sham control arm, the efficacy of 10 kHz SCS in this patient cohort will become more established.     

Does Fibromyalgia Affect the Outcomes of Spinal Cord Stimulation: An 11-Year,Multicenter, Retrospective Matched Cohort Study

BackgroundFibromyalgia is a prevalent disorder manifesting with widespread musculoskeletal pain and central sensitization, as well as fatigue, sleep issues, psychologic distress, and poor quality of life. Patients with fibromyalgia also may be diagnosed with other painful conditions amenable to treatment with spinal cord stimulation (SCS), although it is unclear how these patients respond to SCS compared with patients without fibromyalgia.Materials and MethodsWe performed an 11-year, multicenter, retrospective matched cohort study comparing SCS-treated patients with fibromyalgia and those without fibromyalgia. The primary outcome was comparison in mean calculated percentage pain relief between cohorts at six months after SCS implantation. Secondary outcomes included comparison of patient satisfaction between six and 12 months after SCS implantation, and percentage of patients reporting opioid intake and neuropathic medication intake at six months and 12 months after SCS implantation. Adjusted regression analysis was performed to make comparisons while adjusting for age, sex, body mass index, Charlson comorbidity index, preoperative opioid intake, and preoperative neuropathic medication intake.ResultsOf 90 patients with fibromyalgia who underwent SCS trial, 18 patients (20%) failed their SCS trial and did not proceed toward implantation. Sixty-eight patients with fibromyalgia were matched to 141 patients in the control cohort based on age, sex, Charlson comorbidity index, and the American Society of Anesthesiologists physical status score. At six months after SCS implantation, there was no statistical difference in calculated percentage change in pain intensity between the fibromyalgia cohort (46.6 ± 29.0) and the control cohort (50.9 ± 32.8; β, ?18.4; 95% CI, ?44.3 to 7.6; p = 0.157). At baseline, a greater percentage of patients in the fibromyalgia cohort reported preoperative opioid intake (51.5% vs 22.7%, p < 0.001) and preoperative neuropathic medication intake (67.6% vs 15.6%, p < 0.001). However, there was no difference between cohorts in the percentage of patients taking opioid or neuropathic medications at six months and 12 months after SCS implantation. Similarly, there was no difference between cohorts in the percentage of patients reporting satisfaction between six and 12 months.ConclusionPatients with fibromyalgia who received a diagnosis approved for treatment with SCS may expect similar post–SCS-implantation pain relief, overall satisfaction, and analgesic use rate to those of patients without fibromyalgia.     

Implantable Peripheral Nerve Stimulation for Trigeminal Neuropathic Pain: A Systematic Review and Meta-Analysis

ObjectivesImplantable peripheral nerve stimulation has been increasingly used to treat neuropathic pain. This neuromodulation strategy may be an alternative option for intractable trigeminal neuropathic pain; however, evidence for this treatment approach remains limited. A systematic review was conducted to identify studies of patients that underwent peripheral nerve stimulation implantation for trigeminal neuropathic pain.Materials and MethodsDatabases including, PubMed, EMBASE, and Cochrane Library were searched up to October 5, 2020. The primary outcomes were changes in pain scores and response rates of neuromodulation therapy. A random effects model was used for meta-analysis. Subgroup analysis was performed to examine the source of heterogeneity.ResultsThirteen studies including 221 participants were evaluated. The estimated response rate of neuromodulation treatment was 61.3% (95% CI: 44.4–75.9%, I² = 70.733%, p < 0.0001) at the last follow-up. The overall reduction in pain scores was 2.363 (95% CI: 1.408–3.319, I² = 85.723%, p < 0.0001). Subgroup analysis further confirmed that stimulation target (peripheral branch vs. trigeminal ganglion vs. trigeminal nerve root) contributed the heterogeneity across enrolled studies. Better clinical outcome was associated with stimulation of the trigeminal peripheral branch (p < 0.0001).ConclusionPeripheral nerve stimulation may be a promising approach in the management of trigeminal neuropathic pain, especially for patients intractable to conventional therapy.     

Clinical Outcomes after Spinal Cord Stimulation According to Pain Characteristics

ObjectiveSpinal cord stimulation (SCS) is an effective treatment for chronic neuropathic pain. However, its clinical efficacy in regard to specific types of pain has not been well studied. The primary objective of this study was to retrospectively analyze the clinical outcomes of paddle-type SCS according to the type of neuropathic pain. MethodsSeventeen patients who underwent paddle-lead SCS at our hospital were examined. Clinical outcomes were evaluated pre- and postoperatively (3 months, 1 year, and last follow-up) using the Neuropathic Pain Symptom Inventory (NPSI). The NPSI categorizes pain as superficial, deep, paroxysmal, evoked, or dysesthesia and assess the duration of the pain (pain time score). Changes in NPSI scores were compared with change in Visual analogue scale (VAS) scores. ResultsAfter SCS, the pain time score improved by 45% (independent t-test, p=0.0002) and the deep pain score improved by 58% (independent t-test, p=0.001). Improvements in the pain time score significantly correlated with improvements in the VAS score (r=0.667, p=0.003, Spearman correlation). Additionally, the morphine milligram equivalent value was markedly lower after vs. before surgery (~49 mg, pared t-test, p=0.002). No preoperative value was associated with clinical outcome. ConclusionThe NPSI is a useful tool for evaluating the therapeutic effects of SCS. Chronic use of a paddle-type spinal cord stimulation improved the deep pain and the pain time scores.     

Comparison of Spinal Cord Stimulation Outcomes Between Preoperative Opioid Users and Nonusers: A Cohort Study of 467 Patients

ObjectivesSpinal cord stimulation (SCS) is a surgical treatment modality reserved for a subset of patients with neuropathic pain in which conventional pharmacologic treatment has proven insufficient. Previous studies have suggested a possible negative relationship between opioid use at referral and subsequent success of SCS therapy. The aim of this cohort study was to investigate whether preoperative opioid use was associated with inferior SCS outcomes.Materials and MethodsData were obtained from the Danish Neurizon Neuromodulation Database and comprised preoperative registrations of analgesic use, postoperative Patients’ Global Impression of Change (PGIC) ratings, pre- and postoperative pain intensity scores (Numeric Rating Scale), and detailed surgical data. Patients were dichotomized according to preoperative opioid use (users vs nonusers) with subsequent assessment of the latest PGIC rating, reduction in pain intensity, and current treatment status (implanted/explanted). In addition, daily preoperative opioid dosages were quantified in oral morphine equivalents (OME) and correlated to the treatment outcomes.ResultsA total of 467 patients were included; 296 consumed opioids before SCS implantation (median 80 OME/d). Preoperative opioid use was not associated with the latest PGIC rating, reduction in pain intensity (30% or 50%), or risk of undergoing explantation (median follow-up = 3.0 years). Likewise, preoperative median OME per day of opioid users was not correlated with any of the defined outcomes.ConclusionsPreoperative opioid usage did not predict the outcome of SCS therapy in a large cohort of patients permanently implanted with an SCS system. The results do not support withholding otherwise well-indicated SCS therapy in patients with chronic neuropathic pain conditions based merely on preoperative opioid usage.     

Early Experience With a Novel Miniaturized Spinal Cord Stimulation System for the Management of Chronic Intractable Pain of the Back and Legs

IntroductionA novel, spinal cord stimulation (SCS) system with a battery-free miniaturized implantable pulse generator (IPG) was used in this feasibility study. The system uses an external power source that communicates bidirectionally with the IPG (< 1.5 cm³). Human factors, subject comfort, and effects on low back and leg pain were evaluated in this first-in-human study.Materials and MethodsA prospective, multicenter, open-label clinical trial was initiated to evaluate the safety and performance of a novel miniaturized stimulator in the treatment of chronic, intractable leg and low-back pain. Eligible subjects were recruited for the study and gave consent. Subjects who passed the screening/trial phase (defined as ≥ 50% decrease in pain) continued to the long-term implant phase and were followed up at predefined time points after device activation. Interim clinical and usability outcomes were captured and reported at 90 days.ResultsResults of 22 subjects who chose a novel pulsed stimulation pattern therapy using the battery-free IPG (< 1.5 cm³) are described here. At 90-days follow-up, the average pain reduction was 79% in the leg (n = 22; p < 0.0001) and 76% in the low back (n = 21; p < 0.0001) compared with baseline. Responder rates (≥ 50% pain relief) at 90 days were 86% in leg pain (19/22) and 81% in low-back pain (17/21). Subjects rated the level of comfort of the external wearable power source to be 0.41 ± 0.73 at 90 days on an 11-point rating scale (0 = very comfortable, 10 = very uncomfortable).DiscussionThese interim results from the ongoing study indicate the favorable efficacy and usability of a novel, externally powered, battery-free SCS IPG (< 1.5 cm³) for leg and low-back pain. Study subjects wore the external power source continuously and found it comfortable, and the system provided significant pain relief. These preliminary findings warrant further investigation.Clinical Trial RegistrationThe Clinicaltrials.gov registration number for the study is ACTRN12618001862235.     

Novel Spinal Cord Stimulation Waveforms for Treating Back and Leg Pain: A Systematic Review and Meta-Analysis of Randomized Controlled Trials

BackgroundSpinal cord stimulation (SCS) has been suggested as a treatment option to improve the quality-adjusted life years of individuals with low back pain. However, previous reviews have some methodologic limitations. This review aims to evaluate the effectiveness of novel SCS waveforms on pain outcomes in patients with low back pain (LBP) compared with traditional SCS or placebo comparator.Materials and MethodsNine electronic data bases, ongoing trials, gray literature, and targeted journals were searched from inception to December 27, 2021. The Cochrane risk of bias and Grading of Recommendation, Assessment, Development, and Evaluations were used to appraise individual and overall evidence. Subjects aged ≥ 18 years with or without previous surgeries and having LBP for at least three months were included. The primary outcome was pain intensity including back or leg pain scores at postintervention. Secondary outcomes comprised decrease in back, leg, and overall pain, and health-related quality of life.ResultsA total of 11 randomized controlled trials (RCTs) involving 955 participants across four countries were included. Our meta-analysis revealed that novel SCS waveform was superior to traditional SCS or placebo comparator for treating leg pain (Z = −2.12, p = 0.03) with a small effect size (Hedges’ g = −0.18, 95% CI: −0.34 to −0.01). Back-pain intensity (g = −0.22, 95% CI: −0.47 to 0.02) and health-related quality of life (g = −0.12, 95% CI: −0.43 to 0.18) were similar between the novel SCS waveform group and the traditional SCS or placebo comparator groups. The meta-regression did not identify any effect of the covariates on back-pain intensity.ConclusionsWith low certainty of evidence, this finding provides a rationale for considering the novel SCS waveform as complements to the usual therapeutic plan. Future trials should adopt well-designed RCTs with larger sample size and follow-up assessment.     

Dorsal Root Ganglion Stimulation as a Salvage Therapy Following Failed Spinal Cord Stimulation

IntroductionSpinal cord stimulation (SCS) can provide long-term pain relief for various chronic pain conditions, but some patients have no relief with trial stimulation or lose efficacy over time. To “salvage” relief in patients who do not respond or have lost efficacy, alternative stimulation paradigms or anatomical targets can be considered. Dorsal root ganglion stimulation (DRG-S) has a different mechanism of action and anatomical target than SCS.ObjectivesWe assessed DRG-S salvage therapy outcomes in patients who did not respond to SCS or had lost SCS efficacy.Materials and MethodsWe retrospectively included consecutive patients from 2016 to 2020 who were salvaged with DRG-S after failed SCS trials (<50% pain reduction) or who had lost efficacy after permanent SCS. We compared numerical rating scale (NRS) pain, Oswestry disability index (ODI), health-related quality of life (EuroQol five-dimensions five-level), and oral morphine equivalent (OME) opioid requirements before DRG-S salvage and at patients’ last follow-up.ResultsA total of 60 patients who had failed SCS were salvaged with DRG-S. The mean age was 56 ± 12 years, and the most common diagnoses were complex regional pain syndrome (n = 24) and failed back surgery syndrome (n = 24). The most common failed modalities included tonic (n = 32), Burst (n = 18), and high-frequency (n = 10) SCS. The median follow-up duration of salvage DRG-S was 34 months. With DRG-S, NRS decreased (8.7 ± 1.2 to 3.8 ± 2.1), and OME declined (median 23 mg to median 15 mg), whereas EuroQol 5D scores increased (0.40 ± 0.15 to 0.71 ± 0.15), and ODI improved (64 ± 14% to 31 ± 18%) (all p < 0.05).ConclusionsDRG-S can be used in patients with chronic pain who have previously failed to receive persistent benefit from SCS.     

Pain Catastrophizing Does Not Predict Spinal Cord Stimulation Outcomes: A Cohort Study of 259 Patients With Long‐Term Follow‐Up

ObjectiveSpinal cord stimulation (SCS) is an important treatment modality used to treat chronic neuropathic pain. However, reported success rates of 26%-70% entail an increased focus on patient selection. An area of core interest is psychological evaluation, often using scales such as the Pain Catastrophizing Scale (PCS). The aim of this study was to assess the relation between baseline PCS scores obtained before implantation and SCS outcomes defined as (1) Rating on Patients’ Global Impression of Change scale (PGIC), (2) Pain relief on the Numeric Rating Scale (NRS), (3) Cessation of pain medication, and (4) Risk of permanent explantation.Materials and MethodsUsing records from the Neurizon Neuromodulation Database, we performed a multicenter open cohort study of 259 permanently implanted SCS patients. Follow-up ranged from six months to nine years (median = three years). For each of the defined SCS outcomes, patients were grouped according to their latest follow-up registration. Subsequently, we used a one-way ANOVA and exact t-tests to compare mean baseline PCS scores between groups.ResultsNo difference in mean baseline PCS scores was found between PGIC groups. Baseline PCS scores was not associated with the probability of obtaining 30% or 50% pain relief on latest registration. Baseline PCS scores of patients able to cease all usage of tricyclic antidepressants, antiepileptics, or opioids during SCS treatment did not differ from baseline scores of continuous users. We found no association between baseline PCS scores and risk of permanent explantation.ConclusionThis study did not demonstrate any associations between baseline PCS scores and SCS outcomes.     

High-Dose Spinal Cord Stimulation Reduces Long-Term Pain Medication Use in Patients With Failed Back Surgery Syndrome Who Obtained at Least 50% Pain Intensity and Medication Reduction During a Trial Period: A Registry-Based Cohort Study

ObjectivesHigh-dose spinal cord stimulation (HD-SCS) revealed positive results for obtaining pain relief in patients with failed back surgery syndrome (FBSS). However, it is less clear whether HD-SCS also is able to reduce pain medication use. The aim of this registry-based cohort study is to explore the impact of HD-SCS on pain medication use in FBSS patients.Materials and MethodsData from the Discover registry was used in which the effectiveness of HD-SCS was explored in neurostimulation-naïve FBSS patients as well as in rescue patients. All neurostimulation-naïve FBSS patients positively responded to a four-week SCS trial period in which at least 50% pain relief and 50% medication reduction were obtained. Medication use was measured with the Medication Quantification Scale III (MQS) in 259 patients at baseline and at 1, 3, and 12 months of HD-SCS. Additionally, defined daily doses (DDD) and morphine milligram equivalents (MME) were calculated as well.ResultsOne hundred thirty patients reached the visit at 12 months. In neurostimulation-naïve patients, a statistically significant decrease in MQS (χ² = 62.92, p < 0.001), DDD (χ² = 11.47, p = 0.009), and MME (χ² = 21.55, p < 0.001) was found. In rescue patients, no statistically significant improvements were found. In both patient groups, statistically significant reductions in the proportion of patients on high-risk MME doses ≥90 were found over time. At the intraindividual level, positive correlations were found between MSQ scores and pain intensity for back (r = 0.56, r = 0.31, p < 0.001) and leg pain (r = 0.61, r = 0.22, p < 0.001) in neurostimulation-naïve and rescue patients, respectively.ConclusionsRegistry data on HD-SCS in FBSS patients revealed a statistically significant and sustained decrease in pain medication use, not only on opioids, but also on anti-neuropathic agents in neurostimulation-naïve patients, who positively responded to an SCS trial period with at least 50% pain relief and 50% pain medication decrease, but not in rescue patients.     

How Should we Use Multicolumn Spinal Cord Stimulation to Optimize Back Pain Spatial Neural Targeting? A Prospective,Multicenter, Randomized,Double-Blind,Controlled Trial (ESTIMET Study)

BackgroundRecent studies have highlighted multicolumn spinal cord stimulation (SCS) efficacy, hypothesizing that optimized spatial neural targeting provided by new-generation SCS lead design or its multicolumn programming abilities could represent an opportunity to better address chronic back pain (BP).ObjectiveTo compare multicolumn vs. monocolumn programming on clinical outcomes of refractory postoperative chronic BP patients implanted with SCS using multicolumn surgical lead.Materials and MethodsTwelve centers included 115 patients in a multicenter, randomized, double-blind, controlled trial. After randomization, leads were programmed using only one or several columns. The primary outcome was change in BP visual analogic scale (VAS) at six months. All patients were then programmed using the full potential of the lead up until 12-months follow-up.ResultsAt six months, there was no significant difference in clinical outcomes whether the SCS was programmed using a mono or a multicolumn program. At 12 months, in all patients having been receiving multicolumn SCS for at least six months (n = 97), VAS decreases were significant for global pain (45.1%), leg pain (55.8%), and BP (41.5%) compared with baseline (p < 0.0001).ConclusionThe ESTIMET study confirms the significant benefit experienced on chronic BP by patients implanted with multicolumn SCS, independently from multicolumn lead programming. These good clinical outcomes might result from the specific architecture of the multicolumn lead, giving the opportunity to select initially the best column on a multicolumn grid and to optimize neural targeting with low-energy requirements. However, involving more columns than one does not appear necessary, once initial spatial targeting of the “sweet spot” has been achieved. Our findings suggest that this spatial concept could also be transposed to cylindrical leads, which have drastically improved their capability to shape the electrical field, and might be combined with temporal resolution using SCS new modalities.     

Spinal Cord Stimulation: A Reasonable Alternative Treatment in Patients With Symptomatic Adult Scoliosis for Whom Surgical Therapy Is Not Suitable? A Pilot Study

IntroductionIn adult scoliosis, dorsal instrumentation and fusion can provide significant improvement of pain and disability scores (Owestry Index); however, complication rates of up to 39% have been reported. As such, recent attempts have been made at expanding the surgical spectrum to include less invasive techniques in patients such as neuromodulation, specifically spinal cord stimulation (SCS). We therefore aimed to evaluate its use in a larger cohort of adult scoliosis patients in the form of a pilot study.Materials and MethodsWe analyzed prospectively collected data from 18 adult scoliosis patients receiving SCS treatment in our institution between February 2019 and May 2020. Clinical follow-up was performed at 3, 6, and 12 months following implantation of an epidural SCS System. Patients reported numeric rating scale (NRS) values for the categories of lower back pain (LBP) and regional pain (RP) both at rest and in motion. Further, SF-36, ADS-K, PSQI, and ODI forms were completed. The study was approved by the institutional Ethics Committee (EA2/093/13).ResultsInitial preoperative NRS of LBP at rest was significantly reduced following SCS at three (45% reduction, p = 0.005) and six (43% reduction, p = 0.009) months follow-up. LBP in motion was also reduced at three (27% reduction, p = 0.002) and six (33% reduction vs. preoperative, p = 0.005) months. RP at rest was reduced at three (38% reduction, p = 0.003) and six (37% reduction, p = 0.007) and in movement at three (29% reduction, 0.006) and six (32% reduction, p = 0.011). Loss of thoracic kyphosis and increased pelvic incidence were associated with worse NRS response to SCS stimulation at six months follow-up.DiscussionIn overweight, older adults for whom the risks of corrective surgery must be carefully considered, neuromodulation can significantly reduce LBP as well as regional pain in the first six months following implantation. These findings may provide a reasonable alternative in patients not willing or eligible to undergo extensive corrective surgery.     

Spinal Cord Stimulation to Treat Low Back Pain in Patients With and Without Previous Spine Surgery

ObjectivesLittle is known about the effects of spinal cord stimulation (SCS) on chronic low back pain (CLBP) patients with no history of previous spine surgery. Using our prospectively collected database, we evaluate improvements in patients with and without previous spine surgery one-year post SCS implantation.Materials and MethodsSubjects completed outcome metrics pre-operatively and one-year post-implantation including Numeric Rating Scale (NRS), McGill Pain Questionnaire (MPQ), Oswestry Disability Index (ODI), Beck’s Depression Inventory (BDI), and Pain Catastrophizing Scale (PCS).ResultsWe enrolled 134 patients; 82 patients had previous spine surgery and 52 patients did not. At one-year post-SCS implantation, patients with previous spine surgery showed improvements in worst pain experienced, least pain experienced, average pain experienced, pain felt currently, MPQ, MPQ sensory, MPQ affective, PCS, PCS helplessness, PCS rumination, PCS magnification, ODI, and BDI scores (p < 0.001, p = 0.005, p < 0.001, p < 0.001, p < 0.001, p < 0.001, p = 0.03, p = 0.01, p = 0.02, p < 0.001, p = 0.05, p < 0.001, p = 0.017, respectively). Likewise, patients without previous spine surgery showed improvements in worst pain experienced, least pain experienced, average pain experienced, pain felt currently, MPQ, MPQ sensory, PCS, PCS helplessness, PCS rumination, PCS magnification, ODI, and BDI scores (p < 0.001, p = 0.005, p < 0.001, p < 0.001, p < 0.001, p < 0.001, p < 0.001, p < 0.001, p < 0.001, p = 0.008, p < 0.001, p < 0.001, respectively). Patients without previous spine surgery showed greater improvements for average pain PCS helplessness (p = 0.01).ConclusionsPatients with and without previous spine surgery showed similar improvements in pain intensity, pain quality, feelings of rumination and magnification, functional disability, and depression severity. SCS can improve CLBP regardless of whether patients have had previous spine surgery.     

Analgesic Efficacy of “Burst” and Tonic (500 Hz) Spinal Cord Stimulation Patterns: A Randomized Placebo-Controlled Crossover Study

ObjectiveSThe aim of this study was to compare the efficacy in reducing pain intensity in adult subjects suffering from chronic back and leg pain of burst (BST) and tonic sub-threshold stimulation at 500 Hz (T500) vs. sham stimulation delivered by a spinal cord stimulation (SCS) device capable of automated postural adjustment of current intensity.Materials and MethodsA multicentre randomized double-blind, three-period, three-treatment, crossover study was undertaken at two centers in the United Kingdom. Patients who had achieved stable pain relief with a conventional SCS capable of automated postural adjustment of current intensity were randomized to sequences of BST, T500, and sham SCS with treatment order balanced across the six possible sequences. A current leakage was programmed into the implantable pulse generator (IPG) in the sham period. The primary outcome was patient reported pain intensity using a visual analog scale (VAS).ResultsNineteen patients were enrolled and randomized. The mean reduction in pain with T500 was statistically significantly greater than that observed with either sham (25%; 95% CI, 8%–38%; p = 0.008) or BST (28%; 95% CI, 13%–41%; p = 0.002). There were no statistically significant differences in pain VAS for BST versus Sham (5%; 95% CI, −13% to 27%; p = 0.59). Exploratory sub-group analyses by study site and sex were also conducted for the T500 vs. sham and BST versus sham comparisons.ConclusionsThe findings suggest a superior outcome versus sham from T500 stimulation over BST stimulation and a practical equivalence between BST and sham in a group of subjects with leg and back pain habituated to tonic SCS and having achieved a stable status with stimulation.     

Surgical Paddle Electrode Implantation as a Rescue Therapy to Failed Percutaneous Leads in Failed Back Surgery Syndrome Patients

IntroductionSpinal cord stimulation (SCS) to treat failed back surgery syndrome (FBSS) can be provided with either percutaneously or surgically implanted electrodes. Percutaneous electrodes are considered the first choice in many pain practices, but surgical paddle electrodes can also be indicated if a percutaneous electrode fails to retain sufficient pain relief or if percutaneous implantation is considered unachievable. Although the current efficacy of surgical paddle electrodes has been based mainly upon pain intensity scores, the evidence on surgical paddle electrodes as a rescue to failed percutaneous electrodes remains even more scarce.ObjectiveThis study aimed to evaluate the safety and clinical effectiveness of rescue surgical paddle electrodes in FBSS patients, multidimensionally.Materials and MethodsThe occurrence of complications, pain intensity scores, psychosocial-related questionnaires, and medication intake were collected. Subsequently, a Quality-of-Life Index (QLI) was calculated. A clinically relevant effect was obtained if the minimal clinically important difference regarding pain intensity was reached.ResultsA total of 25 patients were included in the study. The pain intensity scores were significantly reduced (p < 0.001), and clinically relevant reductions occurred during short-term (0–6 months), mid-term (1–3 years), and long-term follow-up (≥4 years). The structural morphine usage and QLI were significantly decreased at short-term follow-up (p = 0.038 and p = 0.036, respectively). Six complications occurred in five patients, of which, four concerned hardware-related problems and two were of biological origin.ConclusionSCS utilizing a surgical paddle electrode as a salvage treatment to failed conventional percutaneous cylindrical lead SCS can be practiced safely and effectively to treat FBSS. Because of potentially improved clinical effectiveness and cost-effectiveness resulting from fewer reoperations, a SCS treatment algorithm may benefit from expediting surgical paddle electrodes.     

Paresthesia‐Free Spinal Nerve Root Stimulation for the Treatment of Chronic Neuropathic Pain

ObjectiveStimulation of the dorsal spinal roots, or spinal nerve root stimulation (SNRS), is a neuromodulation modality that can target pain within specific dermatomal distributions. The use of paresthesia-free stimulation has been described with conventional dorsal column spinal cord stimulation, although has yet to be described for SNRS. This objective of this study was to investigate the efficacy of paresthesia-free high-frequency (1000–1200 Hz) SNRS in the treatment of intractable, dermatomal neuropathic pain.Materials and MethodsA retrospective chart review was performed on 14 patients implanted with SNRS in varying distributions: Ten patients initially received tonic stimulation and crossed over to a paresthesia-free paradigm and four patients received only paresthesia-free stimulation. The primary outcome was reduction in pain severity (visual analog scale [VAS]), measured at baseline and follow-up to 24 months with paresthesia-free stimulation.ResultsAll 14 patients who received paresthesia-free stimulation had significant improvement in pain severity at a mean follow-up of 1.39 ± 0.15 years (VAS 7.46 at baseline vs. 3.25 at most recent follow-up, p < 0.001). Ten patients were initially treated with tonic stimulation and crossed over to paresthesia-free stimulation after a mean of 61.7 months. Baseline pain in these crossover patients was significantly improved at last follow-up with tonic stimulation (VAS 7.65 at baseline vs. 2.83 at 48 months, p < 0.001), although all patients developed uncomfortable paresthesias. There was no significant difference in pain severity between patients receiving tonic and paresthesia-free stimulation.ConclusionsWe present real-world outcomes of patients with intractable dermatomal neuropathic pain treated with paresthesia-free, high-frequency SNRS. We demonstrate its effectiveness in providing pain reduction at a level comparable to tonic SNRS up to 24 months follow-up, without producing uncomfortable paresthesias.     

Spinal Cord Stimulation With Additional Peripheral Nerve/Field Stimulation Versus Spinal Cord Stimulation Alone on Back Pain and Quality of Life in Patients With Persistent Spinal Pain Syndrome

IntroductionPersistent spinal pain syndrome (PSPS) or failed back surgery syndrome (FBSS) refers to new or persistent pain following spinal surgery for back or leg pain in a subset of patients. Spinal cord stimulation (SCS) is a neuromodulation technique that can be considered in patients with predominant leg pain refractory to conservative treatment. Patients with predominant low back pain benefit less from SCS. Another neuromodulation technique for treatment of chronic low back pain is subcutaneous stimulation or peripheral nerve field stimulation (PNFS). We investigated the effect of SCS with additional PNFS on pain and quality of life of patients with PSPS compared with that of SCS alone after 12 months.Materials and MethodsThis is a comparative study of patients with PSPS who responded to treatment with either SCS + PNFS or SCS only following a multicenter randomized clinical trial protocol. In total, 75 patients completed the 12-month follow-up: 21 in the SCS-only group and 54 in the SCS + PNFS group. Outcome measures were pain (visual analog scale), quality of life (36-Item Short Form Survey [SF-36]), anxiety and depression (Hospital Anxiety and Depression Scale [HADS]), overall health (EuroQol Five-Dimension [EQ-5D]), disability (Oswestry Disability Index [ODI]), and pain assessed by the McGill questionnaire.ResultsThere were no significant differences in baseline characteristics between the two groups. Both groups showed a significant reduction in back and leg pain at 12 months compared with baseline measurements. No significant differences were found between the groups in effect on both primary (pain) and secondary parameters (SF-36, HADS, EQ-5D, ODI, and McGill pain).ConclusionIn a subgroup of patients with chronic back and leg pain, SCS alone provided similar long-term pain relief and quality-of-life improvement as PNFS in addition to SCS. In patients with refractory low back pain not responding to SCS alone, adding PNFS should be recommended.Clinical Trial RegistrationThe Clinicaltrials.gov registration number for the study is NCT01776749.     

Health‐Related Quality of Life Associated With Pain Health States in Spinal Cord Stimulation for Chronic Neuropathic Pain

ObjectivesA substantial proportion of patients have recently reported pain reduction levels of ≥80% following treatment with Evoked Compound Action Potential (ECAP) spinal cord stimulation (SCS). The additional health-related quality of life (HRQoL) utility gain that can be achieved in this patient group is unclear. The aim of this study is to quantify the HRQoL utility values seen in a remission health state (defined as ≥80% pain reduction) and contrast with more traditional health states of <50% and ≥50% pain relief.Materials and MethodsPain intensity assessed using a 100 mm visual analogue scale (VAS) and EQ-5D-5L questionnaires were collected from 204 patients treated with ECAP SCS for chronic back and leg pain and followed up to 12 months. Utility values were derived using EQ-5D-5L responses crosswalked to EQ-5D-3L. Linear regression models adjusted for baseline utility values and patient demographics were used to compare differences in utility values across health states.ResultsPatients in the remission health state (i.e., ≥80% pain reduction) consistently reported statistically significant greater utility values (+0.09 to +0.15, all p < 0.003) compared to patients reporting ≥50% pain relief at 3- and 12-month follow-up for overall, back, and leg VAS pain. The gain in utility values per percent unit of pain reduction was statistically significant at 3- and 12-month follow-up with a mean increase in HRQoL utility score between 0.003 and 0.005 observed for each percent of pain reduction.ConclusionOur analyses show that patients in a remission health state report statistically and clinically significant better HRQoL than patients experiencing lesser pain relief.     

Racial and Socioeconomic Disparities in Spinal Cord Stimulation Among the Medicare Population

IntroductionSpinal cord stimulation (SCS) is used in the treatment of many chronic pain conditions. This study investigates racial and socioeconomic disparities in SCS among Medicare patients with chronic pain.Materials and MethodsPatients over the age of 18 with a primary diagnosis of postlaminectomy syndrome (ICD-10 M96.1) or chronic pain syndrome (ICD-10 G89.4) were identified in the Center for Medicare and Medicaid Services (CMS) Medicare Claims Limited Data Set. We defined our outcome as SCS therapy by race and socioeconomic status. Multivariable logistic regression was used to determine the variables associated with SCS.ResultsWe identified 1,244,927 patients treated between 2016 and 2019 with a primary diagnosis of postlaminectomy syndrome (PLS) or chronic pain syndrome (CPS). Of these patients, 59,182 (4.8%) received SCS. Multivariable logistic regression analysis revealed that, compared with White patients, Black (OR [95%CI], 0.62 [0.6–0.65], p < 0.001), Asian (0.66 [0.56–0.76], p < 0.001), Hispanic (0.86 [0.8–0.93], p < 0.001), and North American Native (0.62 [0.56–0.69], p < 0.001) patients were significantly less likely to receive SCS. In addition, patients who were dual-eligible for Medicare and Medicaid were significantly less likely to receive SCS than those eligible for Medicare only (OR = 0.38 [95% CI: 0.37–0.39], p < 0.001).ConclusionsThis study suggests that racial and socioeconomic disparities exist in SCS among Medicare and Medicaid patients with PLS and CPS. Further work is required to elucidate the complex etiology underlying these findings.     

A Retrospective Comparison of Long-Term Treatment Results of Subcutaneous Stimulation and Spinal Cord Stimulation for Chronic Neuralgia

ObjectivesSpinal cord stimulation (SCS) is known to be an effective long-term treatment option for chronic neuropathic pain. Subcutaneous stimulation (SubQ) is increasingly used to treat chronic back and neck pain, but long-term outcomes are unclear.Materials and MethodsPatients with neurostimulation devices implanted during the past 16 years were evaluated. Their continuation or termination of the treatment was taken as a measure of long-term treatment success. Age, sex, underlying pain condition, stimulation modality (SCS, SubQ, or hybrid), occurrence, and reasons for treatment termination were documented. Patients were classified as long-term responders and long-term nonresponders and analyzed with their clinical data and stimulation modality. The sample consisted of 98 patients. Of these, 66 were treated with SCS, 21 with SubQ, and 11 with a hybrid system.ResultsApproximately 61.3% of patients receiving SubQ terminated the treatment within two years because of ineffectiveness, whereas only 28.8% of patients receiving SCS terminated their stimulation. Back and neck pain were associated with treatment termination (p = 0.011). SubQ was also significantly associated with treatment termination.ConclusionsSubQ seems not to provide substantial long-term pain relief for back and neck pain because most patients abandoned their stimulation therapy.