Incidence of Lead Migration With Loss of Efficacy or Paresthesia Coverage After Spinal Cord Stimulator Implantation: Systematic Review and Proportional Meta-Analysis of Prospective Studies and Randomized Clinical Trials

Noninfectious Complications of Dorsal Root Ganglion Stimulation: A Systematic Review and Meta-Analysis

INTRODUCTION

Dorsal root ganglion stimulation (DRGS) has emerged as a promising treatment for chronic neuropathic pain. However, its safety and complications are not fully understood, with existing literature primarily based on case reports, observational studies, and data base analyses. This systematic review and meta-analysis aims to assess the prevalence of noninfectious complications associated with DRGS, focusing on the trial phase, postimplantation period, and revisions, while identifying risk factors for these outcomes.

MATERIALS AND METHODS

This systematic review adhered to Preferred Reporting Items for Systematic reviews and Meta-Analyses guidelines and was registered in the International Prospective Register of Systematic Reviews database. A comprehensive search was conducted across multiple data bases in June 2023. Studies included randomized and nonrandomized trials, and cohort studies involving ≥20 patients with DRGS. The exclusion criteria were studies that did not differentiate DRGS-specific complications, focused solely on infections, lacked sufficient data for prevalence estimation, or presented only subanalyses from larger studies. A meta-analysis of proportions was performed to estimate the overall prevalence of complications.

RESULTS

Thirteen studies with 634 participants were included. The pooled prevalence of all complications was 37% (95% CI: 19%-57%), with device-related complications being the most common at 27% (95% CI: 15%-42%). Lead fractures and migrations were the most frequently reported device-related complications with, respectively, 6% (95% CI: 2%-12%) and 6% (95% CI: 2%-10%). Procedure-related complications had a pooled prevalence of 1% (95% CI: 0%-5%), with dural puncture being the most common. The prevalence of DRGS explantations was 12%, primarily due to insufficient pain relief.

CONCLUSIONS

DRGS shows a safety profile comparable to that of spinal cord stimulation, with similar rates of lead migrations and fractures. Improvements in surgical techniques, technology, and clinician expertise are expected to reduce complications. Future research should standardize reporting practices and detail implantation techniques to better understand and refine best practices in DRGS implantation.

Catastrophizing as a Predictor for Pain Perception and Disability Among Patients Undergoing Spinal Cord Stimulation

Background and Objectives: The International Society for Modulation defines persistent spinal pain syndrome type 2 (PSPS-type 2), formerly known as failed back surgery syndrome, as a condition where patients continue to experience pain or develop new pain following spinal surgery intended to alleviate back or lower-limb discomfort. PSPS-type 2 is characterized by pain and significant disability, affecting quality of life. Spinal cord stimulation has proven effective in treating this syndrome, although the role of psychological factors, such as pain catastrophizing and central sensitization, remain unclear. This study seeks to examine the potential connection between psychosocial responses and both functionality and pain perception in patients with persistent spinal pain syndrome type 2 who have undergone spinal cord stimulation treatment. Materials and Methods: A single-site, cross-sectional study was conducted on individuals diagnosed with persistent spinal pain syndrome type 2 who were receiving spinal cord stimulation. Study participants were required to meet specific eligibility criteria and were assessed for disability, pain perception, fear of movement, pain catastrophizing, and central sensitization. The spinal cord stimulation procedure involved the placement of electrodes at vertebral levels T8-T11 for precise pain control, with a particular focus on targeting the dorsal root ganglion to alleviate chronic pain. Results: Thirty-seven patients with persistent spinal pain syndrome type 2 have undergone spinal cord stimulation treatment for 4.68 ± 5.25 years. Clinical assessments indicated a pain perception score of 5.6 ± 1.96, Central Sensitization Inventory score of 42.08 ± 18.39, disability score of 37.62 ± 16.13, fear of movement score of 33.11 ± 8.76, and pain catastrophizing score of 28.43 ± 13.14. Finally, pain catastrophizing was significantly associated with pain perception (β = 0.075 and p = 0.008) and disability (β = 0.90 and p < 0.01). Conclusions: Catastrophizing plays a crucial role in pain perception and disability among patients with persistent spinal pain syndrome type 2 receiving spinal cord stimulation. Integrating psychological interventions may improve clinical outcomes for these patients.

Retrograde evoked compound action potentials as an alternative for close-loop spinal cord stimulation

Evoked compound action potential (ECAP) is an important parameter in close-loop spinal cord stimulation (SCS). The recording electrode is typically positioned proximal to the stimulation electrode to capture the antegrade ECAP signals generated by ascending fibers. However, relatively little research has been conducted on retrograde ECAPs. This study investigated retrograde ECAPs using custom-made epidural electrodes in 11 adult male Sprague-Dawley rats. Results show that the average motor threshold (MT) and ECAP threshold (ECAPT) for 11 anesthetized rats were 218.18 ± 69.54 μA and 107.27 ± 27.96 μA, respectively. The ECAP amplitudes increased with increasement of the stimulation current and pulse width (PW), and were larger in awake rats than in anesthetized rats. Additionally, aside from ECAPs recorded by a commercial electrophysiological recorder, ECAPs were also recorded by a custom-made amplifier for the purpose of future long-term implantation, but the custom-made amplifier showed lower signal to noise ratio than the commercial amplifier. In conclusion, this study illustrates that retrograde ECAP may also be considered as a feedback signal for close-loop SCS and more sophisticated ECAP recording circuits are needed to form a close-loop system.

Spinal cord stimulation combined with exercise in patients diagnosed with persistent spinal pain syndrome. Study protocol for a randomized control trial

INTRODUCTION

Administration of spinal cord stimulation to individuals with PSPS-T1/2 may induce supraspinal descending activation. Similarly, exercise is recognized as a fundamental aspect of spinal pain management. Studies have demonstrated its impact on neurophysiological factors, including the release of spinal and supraspinal beta-endorphins, which activate μ-opioid receptors. Therefore, the purpose of this study will be to examine the effect of SCS in combination with lumbo-pelvic stability core training on perceived low back pain, quality of life and disability in PSPS-T2 patients.

METHODS/MATERIALS

A double-blind randomized clinical trial (RCT) has been designed. All participants will be randomized from a pre-set sequence. The intervention design has been elaborated from the CONSORT guidelines. This study has been registered at Clinicaltrial.gov (NCT06272539). Sample size was calculated using G Power® Sample size software (University of Düsseldorf). The calculation was based on a moderate effect size of 0.7 (partial η2 = 0.70, α = .05, power = 0.95), resulting in a total of 40 patients. Assuming a 30% dropout rate, 52 participants will be recruited in total. Two sessions per week will be scheduled for 8 weeks with a total of 16 sessions. Each work session will have a duration of 60 minutes. The exercise will be adapted according to the phases based on the results already published, limiting in each phase the degrees of flexion and extension of the spine to avoid the risk of electrode migration. Primary outcomes will be functionality, satisfaction, strength, psychosocial variables, quality of life and pain perception.

Reoperation Rates and Risk Factors after Spinal Cord Stimulation Revision Surgery

INTRODUCTION

Spinal cord stimulation (SCS) is an effective treatment for patients with refractory chronic pain. Despite its efficacy, rates of reoperation after initial implantation of SCS remain high. While revision rates after index SCS surgeries are well reported, less is known about rates and risk factors associated with repeat reoperations. We sought to evaluate patient, clinical, and surgical characteristics associated with repeat reoperation among patients who underwent an initial SCS revision procedure.

METHODS

We performed a retrospective review of patients who underwent SCS revision surgery performed at a single institution between 2008 and 2022. Patients were stratified by whether they underwent a single revision (SR) or multiple revision (MR) surgeries. Multivariate logistic regression was performed to determine risk factors associated with repeat SCS revision. Kaplan-Meier survival analysis was used to compare rates of devices requiring revision across groups.

RESULTS

A total of 54 patients underwent an initial SCS revision. Of these, 15 (28%) underwent a second revision. The most common indication for revision surgery was lead migration (65%). No significant differences were observed in age, body mass index, comorbidities, lead type, and revision indication among the SR and MR groups. On multivariate adjusted analysis, only cervical lead position was significantly associated with repeat reoperation (OR 7.10, 95% CI [1.14, 44.3], p = 0.036). Time to reoperation after a single and MR SCS surgeries did not differ.

CONCLUSIONS

Among patients who undergo SCS reoperation, a substantial portion requires additional revisions. Cervical lead placement may be associated with a higher risk of repeat revision surgery compared to thoracic lead positioning. Consideration of lead positioning in the decision to perform and undergo reoperation may therefore result in lower revision rates and improved clinical outcomes among SCS patients with MRs.

Identifying SCS Trial Responders Immediately After Postoperative Programming with ECAP Dose-Controlled Closed-Loop Therapy

INTRODUCTION

Drawbacks of fixed-output spinal cord stimulation (SCS) screening trials may lead to compromised trial outcomes and poor predictability of long-term success. Evoked compound action potential (ECAP) dose-controlled closed-loop (CL) SCS allows objective confirmation of therapeutic neural activation and pulse-to-pulse stimulation adjustment. We report on the immediate patient-reported and neurophysiologic treatment response post-physiologic CL-SCS and feasibility of early SCS trial responder prediction.

METHODS

Patient-reported pain relief, functional improvement, and willingness to proceed to permanent implant were compared between the day of the trial procedure (Day 0) and end of trial (EOT) for 132 participants in the ECAP Study undergoing a trial stimulation period. ECAP-based neurophysiologic measurements from Day 0 and EOT were compared between responder groups.

RESULTS

A high positive predictive value (PPV) was achieved with 98.4% (60/61) of patients successful on the Day 0 evaluation also responding at EOT. The false-positive rate (FPR) was 5.6% (1/18). ECAP-based neurophysiologic measures were not different between patients who passed all Day 0 success criteria ("Day 0 successes") and those who did not ("needed longer to evaluate the therapy"). However, at EOT, responders had higher therapeutic usage and dose levels compared to non-responders.

CONCLUSIONS

The high PPV and low FPR of the Day 0 evaluation provide confidence in predicting trial outcomes as early as the day of the procedure. Day 0 trials may be beneficial for reducing patient burden and complication rates associated with extended trials. ECAP dose-controlled CL-SCS therapy may provide objective data and rapid-onset pain relief to improve prognostic ability of SCS trials in predicting outcomes.

TRIAL REGISTRATION

The ECAP Study is registered with ClinicalTrials.gov (NCT04319887).

Sustained relief with spinal cord stimulator despite anterior lead migration: a case report

Lead migration is a common complication of spinal cord stimulation, although anterior migration is rare. While early studies suggested that anterior stimulation may produce analgesic effects, it is thought to be poorly tolerated due to abnormal paresthesia and muscle contractions due to its proximity to the corticospinal tract. This case report presents a unique case of sustained pain relief despite anterior lead migration, which suggests that anterior column stimulation may hold clinical significance for pain management. Further studies are needed to explore its analgesic mechanisms and potential therapeutic application. Strategies to prevent lead migration, particularly in the early postoperative period, are also crucial for optimizing outcomes.

Spinal Cord Stimulator Paddle Lead Revision and Replacement for Misplaced or Displaced Electrodes

OBJECTIVE

Spinal cord stimulators (SCSs) are commonly implanted via a laminotomy or laminectomy. Revision surgery may be necessary in instances of hardware failure or loss of efficacy. It is uncommon for leads to have been initially misplaced in a suboptimal position and revision in these cases necessitates additional dissection for appropriate repositioning. Accordingly, there is concern with a more extensive revision for a potentially higher risk of associated complications. This study aims to describe a series of patients with failed paddle SCS electrodes due to misplacement who underwent revision and replacement.

METHODS

Patients who underwent SCS paddle replacement for misplaced paddles between 2021 and 2023 were identified. Medical charts were reviewed for demographic data, operative details, and incidence of complications.

RESULTS

Sixteen patients underwent thoracic SCS paddle revision and replacement. The mean age was 59.6 ± 12.6 years, with 11 females and 5 males. Misplaced paddles were too lateral (n = 12), too high (n = 2), or incompletely within the epidural space (n = 2). The mean duration from initial implantation to revision surgery was 44.8 ± 47.5 months. The mean operative duration was 126.1 ± 26.9 minutes and all patients required a "skip" laminectomy or laminotomy. No complications were encountered. The mean length of follow-up was 18.4 ± 7.3 months. Mean preoperative pain intensity was 7.9 ± 1.5 and at last follow-up was 3.6 ± 1.7 (P < 0.001). All but 1 patient continued to use their device in follow-up.

CONCLUSIONS

The revision and replacement of misplaced paddle SCS electrodes is a feasible and durable revision strategy, even in long-term implants with extensive scarring.

Spinal Cord Stimulation Paddle-to-Percutaneous Revision: Case Series and Technical Description

OBJECTIVE

Spinal cord stimulators (SCSs) can be implanted via a percutaneous or paddle approach, the latter technique requiring a laminotomy or laminectomy. Revision surgery may be necessary in instances of migrated, misplaced, or failed stimulators. When revision of a percutaneous system is necessary, it is common to replace the electrodes with a paddle SCS. This study aims to describe a case series of patients with failed paddle SCS electrodes who underwent revision with percutaneous SCS hardware.

METHODS

A series of 5 patients were retrospectively analyzed. Medical records were reviewed for demographic data, operative technique, postoperative follow-up, and complications.

RESULTS

Five patients were included in this series. The median age was 63 (range 51-84), and the median duration from initial implantation to revision surgery was 19 months (range 5-60). The median operative duration was 92 minutes (mean 99 ± 19.6 minutes). The median length of follow-up after surgery was 24 months (mean 21.8 ± 6.0 months). All patients had improved pain relief and therapeutic coverage with no complications.

CONCLUSIONS

Paddle-to-percutaneous SCS surgery is a feasible and durable revision option in appropriately selected patients.

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.