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.

Intraoperative neurophysiological monitoring and spinal cord stimulator implantation.

INTRODUCTION: Spinal cord injury (SCI) is one of the most dreaded complications after spinal cord stimulation (SCS) implantation surgery. As a result, intraoperative neurophysiological monitoring (IONM) has been proposed to avoid accidental damage to nervous structures under anesthesia and confirm positioning for optimal stimulation. Our study uses a large administrative claims database to determine the 30-day risk of SCI after SCS implantation. METHODS: This retrospective cohort study used the IBM MarketScan Commercial and Medicare Supplemental Databases from 2016 to 2019. Adult patients undergoing SCS surgical procedures with at least 90 days of follow-up, IONM use, the type of sedation used during the procedure, and subsequent SCI were identified using administrative codes. In addition, logistic regression was used to examine the relationship between various risk factors and subsequent SCI. RESULTS: A total of 9676 patients underwent SCS surgery (64.7% percutaneous implants) during the study period. Nine hundred and forty-four (9.75%) patients underwent SCS implantation with IONM. Conscious sedation, Monitored Anesthesia Care anesthesia, and general anesthesia were used in patients with 0.9%, 60.2%, and 28.6%, respectively. Eighty-one (0.8%) patients developed SCI within 30 days after SCS implant surgery. The SCI rate was higher in the group that underwent IONM (2% vs 0.7%, p value <0.001) during the implantation procedure, reflecting the underlying risk. After adjustment for other factors, the OR of SCI is 2.39 (95% CI: 1.33 to 4.14, p value=0.002) times higher for those with IONM than those without IONM. CONCLUSIONS: Increased SCI risk among patients with IONM likely reflects higher baseline risk, and further research is needed for risk mitigation.

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.

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.

Combined cervical and thoracic spinal cord stimulation for chronic pain: A systematic literature review.

OBJECTIVES: Spinal cord stimulation (SCS) is conventionally placed at either cervical or thoracic spinal regions to treat chronic pain. However, for patients with multiarea pain, concomitant cervical and thoracic SCS (ctSCS) may be necessary to provide sufficient coverage. It remains unknown whether ctSCS is effective and safe. Thus, we aimed to survey the existing literature and assess the efficacy and safety of ctSCS. METHODS: A systematic review of the literature was performed according to the 2020 PRISMA guidelines to investigate pain, functional, and safety outcomes related to ctSCS. Articles between 1990 and 2022 available through PubMed, Web of Science, Scopus, and Cochrane Library databases were included if they assessed these outcomes in the context of ctSCS. Data extracted from articles included study type, number of ctSCS implantations, stimulation parameters, indications for implantation, complications, and frequency. The Newcastle-Ottawa scale was used to assess risk of bias. RESULTS: Three primary studies met our inclusion criteria. Overall, ctSCS was effective in providing analgesia. Pain severity was captured with patient-reported pain scales and changes in analgesic requirements. Various metrics were used to quantify quality of life and functional outcomes. Failed back surgery syndrome was the most common indication for ctSCS implantation. Implanted pulse generator pocket pain was the most common postoperative adverse event. CONCLUSIONS: Despite the limited evidence available, ctSCS seems to be effective and generally well tolerated. The dearth of relevant primary literature illustrates a knowledge gap, and future studies are needed to better clarify the efficacy and safety profile of this SCS variant.

Spinal Cord Stimulators and Intrathecal Pain Pump Removal Versus Retention During Posterior Lumbar Fusion: A Matched Cohort Analysis.

STUDY DESIGN: Retrospective cohort study. OBJECTIVE: To determine risks associated with posterior lumbar arthrodesis after spinal cord stimulator (SCS) and intrathecal pain pump (IPP) insertion. SUMMARY OF BACKGROUND DATA: SCS and IPPs aid in the management of chronic back and radicular pain. Little is known regarding the risks of subsequent fusion with these devices in place. METHODS: The PearlDiver Mariner database was queried for spinal fusion between 2010 and 2020. Study groups were created for indwelling SCS or IPP and matched to a separate cohort without SCS or IPP. Subgroups were created for those who had their device removed and those who retained their device at the time of surgery. Complications up to 2 years postoperatively were reviewed and confounding variables were controlled using multivariable logistic regression. RESULTS: Four thousand five hundred three patients had an indwelling SCS/IPP and underwent posterior lumbar fusion. Compared with patients without history of an SCS/IPP, patients undergoing a lumbar fusion with an SCS/IPP which was removed or retained had higher rates of revision surgery at 1 year [7.3% vs. 5.0%, odds ratio (OR) =1.48, P <0.001] and 2 year (10.8% vs. 7.0%, OR =1.59, P <0.001). For all time intervals, there were higher odds of instrumentation failure (2 y: OR =1.65, P <0.001), and pulmonary complications (2 y: OR =1.18, P <0.001). At 2 years, there were higher odds of surgical site complications (OR 1.15, P =0.02) and urinary complications (OR=1.07, P =0.04). There were no differences in complications up to 2 years postoperatively in patients with an SCS/IPP who had their devices retained or removed ( P >0.05). CONCLUSIONS: Patients with a history of spinal cord stimulators and intrathecal pain pumps are at increased risk of mechanical complications and revision fusion compared with patients without these devices. Patients with an SCS or IPP have similar rates of complications during lumbar fusion whether the device is removed or retained.

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.

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.

Role of patient selection and trial stimulation for spinal cord stimulation therapy for chronic non-cancer pain: a comprehensive narrative review.

BACKGROUND/IMPORTANCE: Patient selection for spinal cord stimulation (SCS) therapy is crucial and is traditionally performed with clinical selection followed by a screening trial. The factors influencing patient selection and the importance of trialing have not been systematically evaluated. OBJECTIVE: We report a narrative review conducted to synthesize evidence regarding patient selection and the role of SCS trials. EVIDENCE REVIEW: Medline, EMBASE and Cochrane databases were searched for reports (any design) of SCS in adult patients, from their inception until March 30, 2022. Study selection and data extraction were carried out using DistillerSR. Data were organized into tables and narrative summaries, categorized by study design. Importance of patient variables and trialing was considered by looking at their influence on the long-term therapy success. FINDINGS: Among 7321 citations, 201 reports consisting of 60 systematic reviews, 36 randomized controlled trials (RCTs), 41 observational studies (OSs), 51 registry-based reports, and 13 case reports on complications during trialing were included. Based on RCTs and OSs, the median trial success rate was 72% and 82%, and therapy success was 65% and 61% at 12 months, respectively. Although several psychological and non-psychological determinants have been investigated, studies do not report a consistent approach to patient selection. Among psychological factors, untreated depression was associated with poor long-term outcomes, but the effect of others was inconsistent. Most RCTs except for chronic angina involved trialing and only one RCT compared patient selection with or without trial. The median (range) trial duration was 10 (0-30) and 7 (0-56) days among RCTs and OSs, respectively. CONCLUSIONS: Due to lack of a consistent approach to identify responders for SCS therapy, trialing complements patient selection to exclude patients who do not find the therapy helpful and/or intolerant of the SCS system. However, more rigorous and large studies are necessary to better evaluate its role.

Ogilvie's syndrome after paddle spinal cord stimulator implantation: An experience report.

Spinal cord stimulation (SCS) is an emerging technology to treat chronic pain from complex regional pain syndrome (CPRS) neuropathy and post-laminectomy syndrome. A rarely reported postoperative complication of SCS paddle implantation is abdominal pain that can result from thoracic radiculopathy. Ogilvie's syndrome (OS) is a disorder characterized by acute dilatation of the colon in the absence of an anatomic lesion that obstructs the flow of intestinal contents, which has seldom been observed after spine surgery. Here, we describe the case of a 70-year-old male who developed OS after SCS paddle implantation resulting in cecal perforation and multi-system organ failure with lethal outcome. We discuss the pathophysiology, present a method measuring the spinal canal to cord ratio (CCR) to prevent the risk of thoracic radiculopathy and OS after paddle SCS implantation, and propose suggestions for management and treatment of this condition.

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.

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.

Is Thoracic Paddle Lead Spinal Cord Stimulator Implantation Safe in an Ambulatory Surgery Center?

OBJECTIVE: Spinal cord stimulation is an effective treatment modality for chronic pain. Although percutaneous leads are commonly placed in the outpatient setting, paddle leads are typically implanted in the inpatient setting. Given the substantial cost savings associated with the ambulatory setting, we aimed to demonstrate the feasibility and safety of thoracic paddle lead implantation in a freestanding ambulatory surgery center (ASC). METHODS: Consecutive patients undergoing thoracic paddle lead implantation at a single freestanding ASC from January 2015 to December 2020 were queried. Demographic, perioperative, and outcome data were collected. Primary outcomes were incidence of intraoperative or immediate postoperative complications and need for inpatient transfer. Secondary outcomes included readmission at 30 and 90 days and reoperation at 30 days, 90 days, and 1 year. RESULTS: A total of 46 patients underwent ambulatory thoracic paddle lead implantation over the study period. Two patients (4.3%) suffered an immediate postoperative complication requiring return to surgery at the ASC-one for an epidural hematoma, and one for a flank hematoma. All but one patient (97.8%) were discharged home on the day of surgery. The overall 30- and 90-day readmission rates were 4.3% and 6.5%, respectively. One patient (2.2%) required reoperation for a mechanical complication. No device-related infections were noted during the follow-up period. CONCLUSIONS: Thoracic laminotomy for paddle lead spinal cord stimulator implantation can be performed in a freestanding ASC with complication rates comparable to the hospital setting. Future comparative studies that assess clinical outcomes and cost are necessary to determine the cost-effectiveness of the ambulatory setting.

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.

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.

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.

Spinal cord stimulator medullary compression-a very rare SCS complication and surgical treatment.

INTRODUCTION: The risk of spinal cord damage after Spinal Cord Stimulator (SCS) implant is a very rare event. In our case report, the patient was affected by a progressively worsening spinal stenosis due to SCS compression. CASE REPORT: The authors describe a progressive paraparesis in a 58-year-old woman with a long history of back pain and multiple spine surgeries. Computed tomography (CT) outlined vertebral canal stenosis corresponding to an electrode array implanted in T9. A posterior T8-T10 spinal cord decompression with explanation of the SCS device was performed and a partial neurological improvement was observed immediately postoperative. DISCUSSION: Spinal cord stimulation has been used since 1967 for the treatment of refractory chronic pain, particularly failed back surgery syndrome (FBSS) and complex regional pain syndrome (CRPS). Still, the mechanism underlying its function is not completely clear. Moreover, complications are mainly related to implant dysfunction and the risk of direct and indirect spinal cord compression is described as exceptional in the literature. Our aim is to describe the case SCS device spinal cord direct compression and its surgical treatment.

Spinal cord stimulation in patients suffering from chronic pain after surgery for spinal intradural tumors: A case report and literature summary.

BACKGROUND: The prevalence of pain after treatment of a spinal intradural tumor is remarkably high, approximately up to 40% of the patients suffer from central neuropathic pain. Publications on spinal cord stimulation (SCS) and its effect on pain caused by intradural spinal tumors are rare. We discuss the case of a patient suffering from chronic pain after removal of a Th7 level meningioma who was successfully treated with SCS and give an overview of the literature. METHODS: MEDLINE database was searched for neuropathic pain and intradural tumors. RESULTS: The initial search identified 35 articles, including hand-searched manuscripts. Six articles were included for analysis. CASE REPORT: A 57-year-old female suffers from neuropathic pain in both legs after surgical removal of a Th7 level intradural meningioma. Postoperative magnetic resonance imaging shows no gross abnormalities, although she developed chronic pain in both legs. Pain in combination with side effects of analgesic intake are too disabling to have decent quality of life. A successful implantation of SCS is achieved at Th5 level as a treatment for the central neuropathic pain, and, at 36 months follow-up, there is significant pain relief and almost complete discontinuation of analgesics. DISCUSSION: Central pain from spinal intradural tumors may have a different mechanism of origin than pain seen after an acute spinal cord injury (SCI). However, the basic principles of neuromodulation are the same in both etiologies, as for successful stimulation intact pathways in the spinal cord are necessary. The efficacy of SCS as treatment in intradural spinal tumors is rarely described as only a handful of case reports are published. Interestingly, the case reports show that stimulation both above and below the lesion can be effective. In patients with incomplete SCI or intradural tumor resection stimulation below the lesion could be considered and tried in a trial setting before definitive implantation.

Disability Pension Did Not Reduce Opioid Use Among Patients With Failed Back Surgery Syndrome Who Were Trialed and Implanted for Spinal Cord Stimulation.

BACKGROUND: Spinal cord stimulation (SCS) is an effective treatment for failed back surgery syndrome (FBSS). In patients with FBSS, opioids have often been initiated, even before SCS is trialed. OBJECTIVE: We studied the effect of retirement on opioid use in patients with chronic pain after failed back surgery. STUDY DESIGN: A retrospective study design. SETTING: The study was conducted at Kuopio University Hospital. METHODS: The study group consisted of all 230 patients with SCS trialed or implanted for FBSS at Kuopio University Hospital Neurosurgery from January 1, 1996 through December 31, 2014. All purchases of prescribed opioids and their daily defined doses, as well as data on working ability, were obtained from the Social Insurance Institution. Patients were divided into 3 groups: SCS trial only, SCS implanted permanently, and SCS implanted but later explanted. We analyzed the differences in opioid use among these groups 2 years before and 2 years after the start of their disability pension (DP). RESULTS: During the follow-up period, a total of 60 patients received a DP. One year before DP, the majority of patients used opioids (n = 43, 72%), and throughout the one-year follow-up after retirement, the number of users increased slightly (n = 46, 77%). In the permanently implanted SCS group, the number of strong opioid users decreased after retirement. Most patients used a moderate dose (0.1-10.5 morphine milligram equivalent/d). Retirement appeared to interrupt dose escalation in all groups, but doses increased further as the follow-up continued. LIMITATIONS: No structured questionnaires were used in this study. Also, many underlying factors contributing to chronic pain were missing. CONCLUSIONS: DP did not reduce the use of opioids in patients with FBSS. Opioid doses were lower and dose escalation less steep with continuous SCS therapy.