Complications of Spinal Cord Stimulators-A Comprehensive Review Article.

PURPOSE OF REVIEW: Spinal cord stimulation has been increasing in influence as an option to regulate pain, especially in the chronic pain patient population. However, even with the numerous changes made to this technology since its inception, it is still prone to various complications such as hardware issues, neurological injury/epidural hematoma, infections, and other biological concerns. The purpose of this article is to thoroughly review and evaluate literature pertaining to the complications associated with percutaneous spinal cord stimulation. RECENT FINDINGS: Lead migration is generally the most common complication of percutaneous spinal cord stimulation; however, recent utilization of various anchoring techniques has been discussed and experienced clinical success in decreasing the prevalence of lead migration and lead fractures. With newer high-frequency systems gaining traction to improve pain management and decrease complications as compared to traditional systems, rechargeable implantable pulse generators have been the preferred power source. However, recent findings may suggest that these rechargeable implantable pulse generators do not significantly increase battery life as much as was proposed. Intraoperative neuromonitoring has seen success in mitigating neurological injury postoperatively and may see more usage in the future through more testing. Though the occurrence of infection and biological complications, including dural puncture and skin erosion, has been less frequent over time, they should still be treated in accordance with established protocols. While many complications can arise following percutaneous spinal cord stimulator implantation, the procedure is less invasive than open implantation and has seen largely positive patient feedback. Hardware complications, the more common issues that can occur, rarely indicate a serious risk and can generally be remedied through reoperation. However, less common cases such as neurological injury, infections, and biological complications require prompt diagnosis to improve the condition of the patient and prevent significant damage.

Device-Related Complications Associated with Cylindrical Lead Spinal Cord Stimulator Implants: A Comprehensive Review.

PURPOSE OF REVIEW: Spinal cord stimulation (SCS) is an increasingly utilized therapy for the treatment of neuropathic pain conditions. Though minimally invasive and reversable, there are several important device-related complications that physicians should be aware of before offering this therapy to patients. The aim of this review is to synthesize recent studies in device-related SCS complications pertaining to cylindrical lead implantation and to discuss etiologies, symptoms and presentations, diagnostic evaluation, clinical implications, and treatment options. RECENT FINDINGS: Device-related complications are more common than biologic complications. Device-related complications covered in this review include lead migration, lead fracture, lead disconnection, generator failure, loss of charge, generator flipping, hardware related pain, and paresthesia intolerance. The use of SCS continues to be an effective option for neuropathic pain conditions. Consideration of complications prior to moving forward with SCS trials and implantation is a vital part of patient management and device selection. Knowledge of these complications can provide physicians and other healthcare professionals the ability to maximize patient outcomes.

Incidence and Management of Hardware-Related Wound Infections in Spinal Cord, Peripheral Nerve Field, and Deep Brain Stimulation Surgery: A Single-Center Study.

INTRODUCTION: Neuromodulation using deep brain stimulation (DBS), spinal cord stimulation (SCS), and peripheral nerve field stimulation (PNFS) to treat neurological, psychiatric, and pain disorders is a rapidly growing field. Infections related to the implanted hardware are among the most common complications and result in health-related and economic burden. Unfortunately, conservative medical therapy is less likely to be successful. In this retrospective study, we aimed to identify characteristics of the infections and investigated surgical and antimicrobial treatments. METHODS: A retrospective analysis was performed of patients with an infection related to DBS, SCS, and/or PNFS hardware over an 8-year period at our institution. Data were analyzed for type of neurostimulator, time of onset of infection following the neurosurgical procedure, location, and surgical treatment strategy. Surgical treatment of infections consisted of either a surgical wound revision without hardware removal or a surgical wound revision with partial or complete hardware removal. Data were further analyzed for the microorganisms involved, antimicrobial treatment and its duration, and clinical outcome. RESULTS: Over an 8-year period, a total of 1,250 DBS, 1,835 SCS, and 731 PNFS surgeries were performed including de novo system implantations, implanted pulse generator (IPG) replacements, and revisions. We identified 82 patients with infections related to the neurostimulator hardware, representing an incidence of 3.09% of the procedures. Seventy-one percent of the patients had undergone multiple surgeries related to the neurostimulator prior to the infection. The infections occurred after a mean of 12.2 months after the initial surgery. The site of infection was most commonly around the IPG, especially in DBS and SCS. The majority (62.2%) was treated by surgical wound revision with simultaneous partial or complete removal of hardware. Microbiological specimens predominantly yielded Staphylococcus epidermidis (39.0%) and Staphylococcus aureus (35.4%). After surgery, antimicrobials were given for a mean of 3.4 weeks. The antimicrobial regime was significantly shorter in patients with hardware removal in comparison to those who only had undergone surgical wound revision. One intracranial abscess occurred. No cases of infection-related death, sepsis, bacteremia, or intraspinal abscesses were found. CONCLUSION: Our data did show the predominance of S. epidermidis and S. aureus as etiologic organisms in hardware-related infections. Infections associated with S. aureus most likely required (partial) hardware removal. Aggressive surgical treatment including hardware removal shortens the duration of antimicrobial treatment. Clear strategies should be developed to treat hardware-related infections to optimize patient management and reduce health- and economic-related burden.

Variables associated with nonresponders to high-frequency (10 kHz) spinal cord stimulation.

INTRODUCTION: The use of spinal cord stimulation (SCS) therapy to treat chronic pain continues to rise. Optimal patient selection remains one of the most important factors for SCS success. However, despite increased utilization and the existence of general indications, predicting which patients will benefit from neuromodulation remains one of the main challenges for this therapy. Therefore, this study aims to identify the variables that may correlate with nonresponders to high-frequency (10 kHz) SCS to distinguish the subset of patients less likely to benefit from this intervention. MATERIALS AND METHODS: This was a retrospective single-center observational study of patients who underwent 10 kHz SCS implant. Patients were divided into nonresponders and responders groups. Demographic data and clinical outcomes were collected at baseline and statistical analysis was performed for all continuous and categorical variables between the two groups to calculate statistically significant differences. RESULTS: The study population comprised of 237 patients, of which 67.51% were responders and 32.49% were nonresponders. There was a statistically significant difference of high levels of kinesiophobia, high self-perceived disability, greater pain intensity, and clinically relevant pain catastrophizing at baseline in the nonresponders compared to the responders. A few variables deemed potentially relevant, such as age, gender, history of spinal surgery, diabetes, alcohol use, tobacco use, psychiatric illness, and opioid utilization at baseline were not statistically significant. CONCLUSION: Our study is the first in the neuromodulation literature to raise awareness to the association of high levels of kinesiophobia preoperatively in nonresponders to 10 kHz SCS therapy. We also found statistically significant differences with greater pain intensity, higher self-perceived disability, and clinically relevant pain catastrophizing at baseline in the nonresponders relative to responders. It may be appropriate to screen for these factors preoperatively to identify patients who are less likely to respond to SCS. If these modifiable risk factors are present, it might be prudent to consider a pre-rehabilitation program with pain neuroscience education to address these factors prior to SCS therapy, to enhance successful outcomes in neuromodulation.

Pocket pain following spinal cord stimulator generator implantation: A narrative review of this under-reported risk.

INTRODUCTION: Spinal cord stimulation (SCS) is a well-established treatment option for chronic pain. Pain over the implantable pulse generator, or pocket pain, is an incompletely understood risk of SCS implantation which may limit the efficacy of treatment and patient quality of life. The goal of this narrative review is to analyze the literature to gain a more thorough understanding of the incidence and risk factors for the development of pocket pain to help guide treatment options and minimize its occurrence in the future. METHODS: A literature review was conducted investigating the development of pocket pain in patients with SCS for the management of a variety of pain conditions. RESULTS: In total, 305 articles were included in the original database search and 50 met the criteria for inclusion. The highest level of evidence for papers that specifically investigated pocket pain was level III. Four retrospective, observational analyses included pocket pain as a primary outcome. The remainder of the included studies listed pocket pain as an adverse event of SCS implantation. CONCLUSIONS: There is a relative dearth of primary literature that examines the incidence, characteristics, and health economic implications of pocket pain in patients with SCS. This highlights the need for large-scale, high-quality prospective or randomized controlled trials examining pocket pain. This may ultimately help prevent and reduce pocket pain leading to improved efficacy of treatment and greater patient quality of life.

Analysis of spinal canal diameter in the placement of thoracic spinal cord stimulator paddle leads.

BACKGROUND: Neurologic deficit is known as a rare complication of thoracic spinal cord stimulator (SCS) paddle lead implantation, but many believe its incidence after SCS paddle lead placement is under-reported. It is possible that imaging characteristics may be used to help predict safe paddle lead placement. OBJECTIVE: This imaging study was undertaken to determine the minimum canal diameter required for safe paddle lead placement. METHODS: Patients who underwent thoracic laminotomy for new SCS paddle lead placement from January 2018 to March 2023 were identified retrospectively. Preoperative thoracic canal diameter was measured in the sagittal plane perpendicular to the disc space from T5/6 to T11/12. These thoracic levels were chosen because they span the most common levels targeted for SCS placement. Patients with and without new neurologic deficits were compared using a Mann-Whitney U-test. RESULTS: Of 185 patients initially identified, 180 had thoracic imaging available for review. One (0.5%) and 2 (1.1%) of 185 patients complained of permanent and transient neurologic deficit after thoracic SCS placement, respectively. Patients with neurologic deficits had average canal diameters of <11 mm. The average canal diameter of patients with and without neurologic deficits was 10.2 mm (range 6.1-12.9 mm) and 13.0 mm (range 5.9-20.2), respectively (p < 0.0001). CONCLUSION: Postoperative neurologic deficit is an uncommon complication after thoracic laminotomy for SCS paddle lead placement. The authors recommend ensuring a starting thoracic canal diameter of at least 12 mm to accommodate a SCS paddle lead measuring 2 mm thick to ensure a final diameter of >10 mm. If canal diameter is <12 mm, aggressive undercutting of the lamina, a second laminotomy, or placement of smaller SCS wire leads should be considered.

Case report: Dorsal root ganglion stimulator lead fracture.

BACKGROUND: One of the unique advances in neuromodulation for chronic pain has been spinal cord stimulators (SCS) and dorsal root ganglion stimulators (DRG-S). These devices have aided in conditions such as neuropathic pain, complex regional pain syndromes, failed back surgery, and peripheral neuropathies. With these benefits, however, complications from implantable stimulators have included lead fractures and migration. The authors reviewed a lead migration, kinking, and subsequent fracture event involving a patient with complex regional pain syndrome (CRPS) II, who was treated with a DRG-S. CASE PRESENTATION: The case report follows this patient, from their past medical history to assessment of appropriate qualifications for neuromodulation, to successful surgical placement, to follow-up care. The authors further monitored assessment of inefficacy of pain relief, and identification of lead migration and kinking through imaging. In the process of removal, due to lead stress, lead fracturing occurred. After lead removal, the leads were fully replaced, and the patient was followed up and experienced improved pain relief. CONCLUSION: The case report assesses probable mechanisms of lead fracture and considerations for physicians for future assessment and triage of neuromodulation efficacy.

4. Painful diabetic polyneuropathy.

INTRODUCTION: Pain as a symptom of diabetic polyneuropathy (DPN) significantly lowers quality of life, increases mortality and is the main reason for patients with diabetes to seek medical attention. The number of people suffering from painful diabetic polyneuropathy (PDPN) has increased significantly over the past decades. METHODS: The literature on the diagnosis and treatment of diabetic polyneuropathy was retrieved and summarized. RESULTS: The etiology of PDPN is complex, with primary damage to peripheral nociceptors and altered spinal and supra-spinal modulation. To achieve better patient outcomes, the mode of diagnosis and treatment of PDPN evolves toward more precise pain-phenotyping and genotyping based on patient-specific characteristics, new diagnostic tools, and prior response to pharmacological treatments. According to the Toronto Diabetic Neuropathy Expert Group, a presumptive diagnosis of "probable PDPN" is sufficient to initiate treatment. Proper control of plasma glucose levels, and prevention of risk factors are essential in the treatment of PDPN. Mechanism-based pharmacological treatment should be initiated as early as possible. If symptomatic pharmacologic treatment fails, spinal cord stimulation (SCS) should be considered. In isolated cases, where symptomatic pharmacologic treatment and SCS are unsuccessful or cannot be used, sympathetic lumbar chain neurolysis and/or radiofrequency ablation (SLCN/SLCRF), dorsal root ganglion stimulation (DRGs) or posterior tibial nerve stimulation (PTNS) may be considered. However, it is recommended that these treatments be applied only in a study setting in a center of expertise. CONCLUSIONS: The diagnosis of PDPN evolves toward pheno-and genotyping and treatment should be mechanism-based.

Spinal cord stimulation for low back pain.

BACKGROUND: Spinal cord stimulation (SCS) is a surgical intervention used to treat persistent low back pain. SCS is thought to modulate pain by sending electrical signals via implanted electrodes into the spinal cord. The long term benefits and harms of SCS for people with low back pain are uncertain. OBJECTIVES: To assess the effects, including benefits and harms, of SCS for people with low back pain. SEARCH METHODS: On 10 June 2022, we searched CENTRAL, MEDLINE, Embase, and one other database for published trials. We also searched three clinical trials registers for ongoing trials. SELECTION CRITERIA: We included all randomised controlled trials and cross-over trials comparing SCS with placebo or no treatment for low back pain. The primary comparison was SCS versus placebo, at the longest time point measured in the trials. Major outcomes were mean low back pain intensity, function, health-related quality of life, global assessment of efficacy, withdrawals due to adverse events, adverse events, and serious adverse events. Our primary time point was long-term follow-up (≥ 12 months). DATA COLLECTION AND ANALYSIS: We used standard methodological procedures expected by Cochrane. MAIN RESULTS: We included 13 studies with 699 participants: 55% of participants were female; mean age ranged from 47 to 59 years; and all participants had chronic low back pain with mean duration of symptoms ranging from five to 12 years. Ten cross-over trials compared SCS with placebo. Three parallel-group trials assessed the addition of SCS to medical management. Most studies were at risk of performance and detection bias from inadequate blinding and selective reporting bias. The placebo-controlled trials had other important biases, including lack of accounting for period and carryover effects. Two of the three parallel trials assessing SCS as an addition to medical management were at risk of attrition bias, and all three had substantial cross-over to the SCS group for time points beyond six months. In the parallel-group trials, we considered the lack of placebo control to be an important source of bias. None of our included studies evaluated the impact of SCS on mean low back pain intensity in the long term (≥ 12 months). The studies most often assessed outcomes in the immediate term (less than one month). At six months, the only available evidence was from a single cross-over trial (50 participants). There was moderate-certainty evidence that SCS probably does not improve back or leg pain, function, or quality of life compared with placebo. Pain was 61 points (on a 0- to 100-point scale, 0 = no pain) at six months with placebo, and 4 points better (8.2 points better to 0.2 points worse) with SCS. Function was 35.4 points (on a 0- to 100-point scale, 0 = no disability or best function) at six months with placebo, and 1.3 points better (3.9 points better to 1.3 points worse) with SCS. Health-related quality of life was 0.44 points out of 1 (0 to 1 index, 0 = worst quality of life) at six months with placebo, and 0.04 points better (0.16 points better to 0.08 points worse) with SCS. In that same study, nine participants (18%) experienced adverse events and four (8%) required revision surgery. Serious adverse events with SCS included infections, neurological damage, and lead migration requiring repeated surgery. We could not provide effect estimates of the relative risks as events were not reported for the placebo period. In parallel trials assessing SCS as an addition to medical management, it is uncertain whether, in the medium or long term, SCS can reduce low back pain, leg pain, or health-related quality of life, or if it increases the number of people reporting a 50% improvement or better, because the certainty of the evidence was very low. Low-certainty evidence suggests that adding SCS to medical management may slightly improve function and slightly reduce opioid use. In the medium term, mean function (0- to 100-point scale; lower is better) was 16.2 points better with the addition of SCS to medical management compared with medical management alone (95% confidence interval (CI) 19.4 points better to 13.0 points better; I2 = 95%; 3 studies, 430 participants; low-certainty evidence). The number of participants reporting opioid medicine use was 15% lower with the addition of SCS to medical management (95% CI 27% lower to 0% lower; I2 = 0%; 2 studies, 290 participants; low-certainty evidence). Adverse events with SCS were poorly reported but included infection and lead migration. One study found that, at 24 months, 13 of 42 people (31%) receiving SCS required revision surgery. It is uncertain to what extent the addition of SCS to medical management increases the risk of withdrawals due to adverse events, adverse events, or serious adverse events, because the certainty of the evidence was very low. AUTHORS' CONCLUSIONS: Data in this review do not support the use of SCS to manage low back pain outside a clinical trial. Current evidence suggests SCS probably does not have sustained clinical benefits that would outweigh the costs and risks of this surgical intervention.

Complications of Spinal Cord Stimulator Trials and Implants: A Review.

PURPOSE OF REVIEW: Spinal cord stimulation (SCS) has been used for decades to alleviate chronic pain. A growing body of literature suggests that the procedure is not without risks. Understanding the risks of SCS implantation can help treating physicians formulate individualized care plans that promote patient safety and minimize risks. RECENT FINDINGS: The overall complication rate associated with SCS has been reported to be 31.9 to 43%. The most common complication in the literature appears to be electrode migration. Other complications ranging in rates of occurrence include hematoma formation, infection, spinal cord injury, and cerebrospinal fluid (CSF) leak. Case reports of syrinx formation, foreign body reaction, and fibrosis have also been described. Our review shows that there are strategies available to reduce and prevent complications. In addition, close monitoring and early intervention may prevent some of the adverse neurological outcomes. Nevertheless, additional research regarding patient and procedural factors is necessary to improve the safety profile of this intervention.

Spinal cord stimulation in non-reconstructable critical limb ischemia: a retrospective study of 71 cases.

BACKGROUND: Spinal cord stimulation (SCS) is a therapeutic option for patients with a peripheral arterial disease with critical limb ischemia (CLI) and consequent ischemic rest pain. Neuromodulation is chosen when vascular reconstruction is not possible or failed. Data about the effect of SCS over limb salvage rates are dissonant. METHOD: We report on a retrospective cohort of CLI patients who were implanted with SCS systems between July 2010 and December 2013 in a single center. Major amputation, postoperative complications, and death were recorded. RESULTS: Seventy-two CLI patients underwent SCS implantation, with 35 of them classified as non-reconstructable and 37 with previous but failed or only partially successful vascular procedures. A total of 21 subjects were at Fontaine's stage III (29.2%), and the remaining 51 were at stage IV (70.8%). In total, 26.4% of the patients had diabetes (n = 19), two of them at Fontaine's stage III. The mean follow-up was 17.1 ± 10.5 months. At the last follow-up, 59.2% of all patients (42/71), 85.7% of Fontaine's stage III (18/21), 48.0% of Fontaine's stage IV (24/50), and 52.6% of diabetic patients (10/19) were alive without major amputation. The probability of limb survival at 12 months was 72% for all patients, 94% for Fontaine's stage III, 62% for Fontaine's stage IV, and 61% for diabetic patients. The probability of survival at 12 months for patients who underwent major limb amputation (n = 25) was 86% with a mean survival time of 31.03 ± 4.63 months. CONCLUSIONS: Non-reconstructable CLI patients treated with SCS can achieve meaningful clinical outcomes with few procedure-related complications. The therapy may be more beneficial in patients classified as Fontaine's Stage III.

Spinal Cord Stimulator (SCS) Placement: Examining Outcomes Between the Open and Percutaneous Approach.

BACKGROUND: Spinal cord stimulator (SCS) placement has been gaining traction as an approach to modulate pain levels for several different chronic pain conditions. This procedure can be performed via a percutaneous or open approach. Data regarding SCS complications are relatively limited. OBJECTIVE: The purpose of this study was to leverage a large national database to examine outcomes between the percutaneous and open SCS placement approaches. Outcomes in this study include length of stay (LOS), complication rates, reoperation rates, and 1-year readmission rates. MATERIALS AND METHODS: Inclusion criteria for the current study is SCS placement between 2015 and 2020, with receipt of an SCS using either a percutaneous approach or an open laminectomy based approach. Encounters included were limited to true SCS placement, such that trial placements were not included in the study. Univariate statistics and multivariable logistic regression was performed to compare outcomes between cohorts. RESULTS: Total SCS case volumes were 9935 between the percutaneous (n = 4477, 45.1%) and open (n = 5458, 54.9%) approach. Patients receiving the percutaneous approach were found to have a mean decrease in LOS of 9.91 hours when compared to those receiving the open approach. The percutaneous approach was significantly associated with the need for reoperation within one year compared to the open approach (odds ratio [OR]: 0.663, p < 0.001), as well as with the need for readmission within 30 days (51.2% vs 40.2%, OR: 0.759, p < 0.001). CONCLUSION: The open approach, when compared to the percutaneous approach, had a longer mean LOS, lower outpatient discharge rates, and higher odds of experiencing an operative complication in comparison to the percutaneous approach. The percutaneous approach had relatively increased odds of thirty-day readmission, although no significant difference in one-year readmission or removal was demonstrated.

Identifying Predictors for Early Percutaneous Spinal Cord Stimulator Explant at One and Two Years: A Retrospective Database Analysis.

OBJECTIVES: Placement of percutaneous spinal cord stimulator (SCS) implant has become a therapeutic option for various chronic pain conditions; however, early surgical explant still occurs. Unfortunately, evidence regarding the incidence of early surgical explant, and patient-specific factors and comorbidities associated with such, is limited and mixed. The objective of this retrospective analysis was to elucidate the incidence and predictors of percutaneous SCS explant within the first two years of device placement. MATERIALS AND METHODS: The PearlDiver-Mariner Patient Record Database of all payer claims was used to identify patients who underwent percutaneous lead SCS implant (leads and generator) with subsequent explant within two years of initial device implant. The primary outcome was to determine the incidence of SCS explant within the first two years of device placement. Secondary outcomes included evaluating the effects of several patient-specific comorbidities on explant rates using univariate regression analysis. RESULTS: Across the database, a total of 52,070 patients who underwent percutaneous lead SCS implant were included, of whom 3104 (5.96%) had SCS explant within the first two years. Most explants occurred within the first-year time interval at 72.8% (2260 patients), whereas only 27.2% (844 patients) had SCS explant between years one and two. At the one-year time interval, covariates associated with an increased odds ratio (OR) (95% CI) of SCS explant were 1) depression (1.39 [1.26, 1.52]), 2) chronic preoperative (1.27 [1.16, 1.39]) or postoperative (1.23 [1,13, 1.36]) opioid use, 3) cannabis abuse (1.58 [1.20, 2.02]), 4) tobacco use (1.13 [1.04, 1.23]), and 5) coagulopathy (1.22 [1.07, 1.38]). In contrast, the OR of explant was lower in patients who were older, men, or had diabetes (complicated or uncomplicated). All associated covariates became nonsignificant after the first year of SCS implant (ie, between the first and second years), and only depression and tobacco use remained as associated factors for device explant. CONCLUSIONS: Our retrospective analysis highlights that the rate of percutaneous SCS explant appears to considerably decrease after the first year of device implant. Furthermore, this analysis sheds additional insights into patients who may be at risk of early percutaneous SCS explant, especially within the first year of device placement, and underscores the importance of a continued multidimensional/biopsychologic assessment in patients with chronic pain.

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 Association of Psychiatric Comorbidities With Short-Term and Long-Term Outcomes Following Spinal Cord Stimulator Placement.

BACKGROUND: Outcomes after spinal cord stimulator (SCS) placement are affected by psychologic comorbidities. It is part of routine practice to do psychologic assessments prior to SCS trials to assess for the presence of maladaptive behavioral patterns. However, few studies have sought to quantify the effect of psychiatric comorbidities on complications, reoperation, and readmission rates. The purpose of this study was to assess the association of psychiatric comorbidities with postprocedural outcomes after SCS implantation. MATERIALS AND METHODS: Inclusion criteria included SCS placement between 2015 and 2020 (percutaneous approach or an open laminectomy-based approach) using Healthcare Corporation of America National Database. Data on psychiatric comorbidities present at the time of SCS implantation surgery were collected. Outcomes of interest included complication rates (defined as lead migration, fracture, malfunction, battery failure, postoperative pain, infection, dural puncture, or neurological injury), reoperation rates (defined as either revision or explant [ie, removal]), and readmission rates within 30-day and 1-year time after SCS implantation. We measured the association between psychiatric comorbidities and outcomes using multivariable regression and reported odds ratio (OR) and respective 95% confidence intervals. RESULTS: A total of 12,751 cases were included. The most common psychiatric comorbidities were major depressive disorder (16.1%) and anxiety disorder (13.4%). In unadjusted univariate analysis, patients with any psychiatric comorbidity had heightened rates of any complication (27.1% vs 19.4%), infection (5.9% vs 1.9%), lead displacement (2.2% vs 1.3%), surgical pain (2.1% vs 1.2%), explant (14.7% vs 8.8%), and readmission rates at one year (54.2% vs 33.8%) (all p < 0.001). In multivariable logistic regression, with each additional psychiatric comorbidity, a patient had increased odds of experiencing any complication (OR = 1.5, 95% CI = 1.36-1.57, p < 0.001), requiring a reoperation (OR = 1.5, 95% CI = 1.37-1.6, p < 0.001), and requiring readmission (OR = 1.7, 99% CI = 1.6-1.8, p < 0.001). CONCLUSIONS: The presence of psychiatric comorbidities was found to be associated with postoperative complication rates, reoperation, and readmission rates after SCS placement. Furthermore, each consecutive increase in psychiatric comorbidity burden was associated with increased odds of complications, reoperation, and readmission. Future studies might consider examining the role of presurgical mental health screening (ie, patient selection, psychologic testing) and treatment in optimizing outcomes for patients with psychiatric comorbidities.

Efficacy and Safety of Cervical and High-Thoracic Dorsal Root Ganglion Stimulation Therapy for Complex Regional Pain Syndrome of the Upper Extremities.

OBJECTIVES: The purpose of this study was to evaluate analgesic and safety considerations for high thoracic and cervical dorsal root ganglion (DRG) neuromodulation for complex regional pain syndrome (CRPS). We hypothesized that DRG neuromodulation would provide sustained analgesia with complications like that of low thoracic or lumbar electrode implantation. MATERIALS AND METHODS: A single-center, retrospective study was conducted of patients with CRPS I or II of the upper extremities, refractory to previous therapies, who were treated with DRG neuromodulation in the upper thoracic and cervical spine. The primary outcome was successful DRG therapy, defined as ≥ 50% pain relief on a Numeric Rating Scale (NRS) 0 to 10 pain scale at six months after implantation. A secondary outcome was a reduction in daily opioid use after DRG therapy. RESULTS: After a DRG stimulation trial, 17 of 20 patients (85%) had ≥ 50% improvement in NRS pain and underwent a permanent pulse generator implant, with 100% endorsing ≥ 50% pain relief at six months. Mean NRS pain scores before DRG neuromodulation were 9.3 ± 1.1, with a mean reduction of 5.5 (95% CI, 4.5-6.6; p < 0.001) at six months. Ten patients were taking opioids at baseline; the median (interquartile range) dose was 45 mg (23 to 120) morphine equivalents (MME), which was reduced to 20 MME (15 to 40) at six months. The median reduction in daily MME use was -25 (95% CI, -100 to 20; p = 0.099). Six of 20 patients (30%) experienced a complication: three had lead migration; two experienced paresthesias; and one had a reduction in shoulder mobility. One patient had symptoms of a reversible spinal cord compression immediately after implant, requiring emergent electrode removal. CONCLUSIONS: DRG neuromodulation for patients with CRPS of the upper extremities produced clinically important analgesia and reduced opioid use for ≥ six months but was associated with one serious complication.

Lead and Pulse Generator Migration After Spinal Cord Stimulation Implantation: Insights From an Analysis of 7322 Patients.

OBJECTIVES: Lead migration (LM) after spinal cord stimulation (SCS) implantation surgery is the most common device-related complication. Our study of lead and implantable pulse generator (IPG) migration using a large administrative claims data base aims to understand rates, risk factors, and outcomes after SCS implantation. MATERIALS AND METHODS: This retrospective cohort study used the IBM® MarketScan® (Armonk, NY) Commercial and Medicare Supplemental Databases from 2016 to 2018. Adult patients who underwent SCS surgical procedures with at least 90 days of follow-up were identified using Current Procedural Terminology (CPT®) codes. Patients with LM and IPG migration after SCS surgery were identified using the International Classification of Diseases, 10th Revision, Clinical Modification (ICD-10 CM) codes. Patients who underwent revision surgery after SCS implantation were identified using the CPT codes and ICD-10 CM codes. In addition, patient characteristics associated with LM or IPG migration, the temporal relationship of migration diagnosis, and revision surgery were evaluated in the cohort. Continuous outcomes were compared between groups using the two-sample Student t-test. The Fisher exact test was used to compare categorical outcomes between groups. RESULTS: A total of 7322 patients (64.4% percutaneous SCS) underwent SCS surgery during the study period. A total of 141 patients (1.9%) had LM or IPG migration. Of those, 116 patients (1.6%) had LM only; 18 patients (0.2%) had IPG migration; and seven patients (0.1%) had LM and IPG migration. The mean duration for migration diagnosis after initial SCS implantation was 168 (±163.1) days. The mean duration to revision surgery after the migration diagnosis was 12.3 (±35.2) days only. Most patients with migration (105, 74.5%) underwent revision surgery. Only younger age (p = 0.02) was associated with migration in this study. CONCLUSIONS: LM and pulse generator migration that required revision surgery occurred in a small proportion of patients who underwent SCS surgical procedures.

Is Spinal Cord Stimulation Still Effective After One or More Surgical Revisions?

OBJECTIVES: Spinal cord stimulation (SCS) is burdened with surgical complications that may require one or several surgical revision(s), challenging its risk/benefit ratio and cost-effectiveness. Our objective was to evaluate its outcome and efficacy after one or more SCS surgical revisions. MATERIALS AND METHODS: We identified and retrospectively analyzed 116 patients treated by tonic paresthesia-based SCS who experienced one or more complication(s) requiring at least one surgical revision. Data collected included initial indication, revision indication, number of revisions, and lead design (paddle or percutaneous). Outcome after SCS revision was evaluated by pain intensity decrease (comparing baseline and postrevision Numerical Rating Scale [NRS] scores) and percentage of patients reporting pain relief ≥50%. Outcome was analyzed according to the number of surgical revisions and the revision indications. RESULTS: Most of the patients (61%) underwent only one revision (mean delay after implantation 44 months). The most frequent causes of revisions were hardware dysfunction (32%), lead migration (23%), and infection (18%). Revision(s) repaired the SCS issue in 87% of the cases. One year after the first revision, 82% of the patients reported pain relief ≥50%, and the mean NRS decrease was 4.0 compared with baseline (p < 0.001). Benefit of SCS revision tended to decrease with the number of revisions but did not differ across revision indications. No serious surgical complications related to the revision occurred, except for three hematomas occurring after repeated revisions. CONCLUSIONS: Our data suggest that surgical revision of SCS system is safe and led to significant pain relief in most of the cases, provided that the initial indication was good and that the previous stimulation was effective. However, success of SCS revision decreases with the number of revisions.

Allodynia, Hyperalgesia, (Quantitative) Sensory Testing and Conditioned Pain Modulation in Patients With Complex Regional Pain Syndrome Before and After Spinal Cord Stimulation Therapy.

OBJECTIVES: Complex regional pain syndrome (CRPS) is a chronic debilitating disease characterized by sensory abnormalities. Spinal cord stimulation (SCS) is an effective therapy for CRPS, but few studies have investigated the effects of SCS therapy on sensory characteristics. Therefore, this study investigated the effect of SCS on allodynia, hyperalgesia, electrical quantitative sensory testing (QST) parameters, and conditioned pain modulation (CPM) effect. MATERIALS AND METHODS: This study is part of a multicenter randomized controlled trial (ISRCTN 36655259). Patients with CRPS in one extremity and eligible for SCS were included. The outcome parameters allodynia (symptom and sign), hyperalgesia (symptom), sensory thresholds with QST, CPM effect, and pain scores were tested before and after three months of SCS (40-Hz tonic SCS). Both the CRPS-affected extremity and the contralateral, clinically unaffected extremity were used to test three sensory thresholds with electrical QST: current perception threshold (CPT), pain perception threshold (PPT), and pain tolerance threshold (PTT). The PTT also was used as a test stimulus for the CPM paradigm both before and after the conditioning ice-water test. Nonparametric testing was used for all statistical analyses. RESULTS: In total, 31 patients were included for analysis. Pain, allodynia (sign and symptom), and hyperalgesia (symptom) were all significantly reduced after SCS therapy. On the unaffected side, none of the QST thresholds (CPT, PPT, and PTT) was significantly altered after SCS therapy. However, the CPT on the CRPS-affected side was significantly increased after SCS therapy. A CPM effect was present both before and after SCS. CONCLUSIONS: Standard 40-Hz tonic SCS significantly reduces pain, hyperalgesia, and allodynia in patients with CRPS. These findings suggest that SCS therapy should not be withheld from patients who suffer from allodynia and hyperalgesia, which contradicts previous findings derived from retrospective analysis and animal research. ISRCTN Registry: The ISRCTN registration number for the study is ISRCTN 36655259.

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

BACKGROUND: Fibromyalgia 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 METHODS: We 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. RESULTS: Of 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; ß, -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. CONCLUSION: Patients 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.