Spinal Cord Stimulator—Trial Lead Migration Study

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.

Radiographic lead migration in percutaneous spinal cord stimulator trials

INTRODUCTION

Lead migration during spinal cord stimulator (SCS) trials is relatively neglected in the literature and presents a different set of challenges compared with fully implanted leads. There is no consensus on what constitutes a clinically significant amount of radiographic lead migration during SCS trials. We wished to evaluate the incidence and extent of radiographic lead migration during percutaneous SCS trials, to investigate the risk factors for lead migration and whether this has impacted on trial success.

METHODS

This prospective observational study of percutaneous SCS trials took place in a tertiary referral center in the UK between April 2021 and January 2022. Radiographs of SCS lead position were taken at baseline and prior to lead removal. Lead migration ≥50% of a vertebral level was deemed significant.

RESULTS

One hundred trials were included comprising 162 leads. Mean migration distance was 0.55 vertebral levels (SD 0.85) or 12.5 mm (SD 18.2) in a caudal direction. Significant radiographic migration occurred in 50% of all leads (81 of 162 leads), at least one lead in 62% of cases and all leads in 44% of cases. Radiographic lead migration was not found to be associated with reduced trial success. A single lead and mechanical anchors were associated with greater incidence of lead migration.

CONCLUSION

Radiographic lead migration of approximately half of a vertebral level in a caudal direction can be expected during percutaneous SCS trials and this can be anticipated by siting leads half of a vertebral level higher to accommodate for this. Additional factors should be considered in the setting of radiographic lead migration to determine whether this can be considered clinically significant.

Analysis of reasons for medical malpractice litigation due to spinal cord stimulator

Study design

Retrospective cohort study.

Introduction

Malpractice claims analysis is performed by several specialties to improve quality of patient care and to identify areas where physicians can improve their practice to mitigate the incidence of committing malpractice. The Food and Drug Administration has flagged over 80,000 injuries caused by spinal cord stimulator (SCS), making them the 3rd most flagged medical device. This study analyzed malpractice claims due to SCS by querying two legal databases widely used in medicolegal research.

Methods

Westlaw Edge and VerdictSearch were queried for malpractice cases filed between the years 2000 and 2022 using the keywords "spinal cord stimulator." Case inclusion criteria was defined as a plaintiff's basis of litigation resting on a claim of medical malpractice due to SCS. Additional data collected included date of case hearing, plaintiff sex and age, defendant specialty, verdict ruling, location of the filed claim, payment or settlement amount, and sustained injuries.

Result

Of the 1773 reviewed cases, 45 cases were included and categorized as battery or implantable pulse generator malfunction (35.56 %), lead complications (28.89 %), surgical complications (20.00 %), and miscellaneous (15.56 %). Four (8.89 %) cases resulted in settlement, 11 (24.44 %) in a plaintiff verdict, and 30 (68.00 %) resulted in a defendant verdict. Claims filed due to infection related to SCS were more likely to result in a defendant verdict (p = .047), whereas claims filed due to neurological deficit were more likely to result in a plaintiff verdict (p = .020). The average settlement amount for the 4 cases is $1,975,309.61.

Conclusion

Our findings suggest obtaining adequate neuroimaging preoperatively with MRIs, disclosing neurological risks specifically paralysis on informed consent, and evaluating radiography intraoperative and postoperatively with anterior-posterior (AP) and lateral x-ray films to ensure proper SCS placement are practices that may mitigate malpractice due to SCS. Battery defects and lead complications were the most common grounds for SCS-related malpractice claims.

FactFinders for patient safety: Preventing potential procedure-related complications: Vasovagal reactions and spinal cord stimulator lead migration

This series of FactFinders presents a brief summary of the evidence and outlines recommendations to improve our understanding and management of several potential procedure-related complications. Evidence in support of the following facts is presented. (1) Vasovagal Reactions During Interventional Pain Procedures -- The overall incidence of vasovagal reactions (VVR) ranges from 1 to 8% during interventional pain procedures, though certain patient populations may be at greater risk. Younger age, male sex, and a history of a VVR are associated with an increased likelihood of VVR. In select patients, moderate sedation may be considered for prevention of a repeat vasovagal reaction. (2) Spinal Cord Stimulator Trial Lead Migration -- Suturing percutaneous SCS leads does not mitigate the risk of migration compared to taping alone during a trial. Most lead migration does not pose a safety concern during the trial period.

High frequency alternating current neurostimulation decreases nocifensive behavior in a disc herniation model of lumbar radiculopathy

BACKGROUND

The purpose of this study was to evaluate if kilohertz frequency alternating current (KHFAC) stimulation of peripheral nerve could serve as a treatment for lumbar radiculopathy. Prior work shows that KHFAC stimulation can treat sciatica resulting from chronic sciatic nerve constriction. Here, we evaluate if KHFAC stimulation is also beneficial in a more physiologic model of low back pain which mimics nucleus pulposus (NP) impingement of a lumbar dorsal root ganglion (DRG).

METHODS

To mimic a lumbar radiculopathy, autologous tail NP was harvested and placed upon the right L5 nerve root and DRG. During the same surgery, a cuff electrode was implanted around the sciatic nerve with wires routed to a headcap for delivery of KHFAC stimulation. Male Lewis rats (3 mo., n = 18) were separated into 3 groups: NP injury + KHFAC stimulation (n = 7), NP injury + sham cuff (n = 6), and sham injury + sham cuff (n = 5). Prior to surgery and for 2 weeks following surgery, animal tactile sensitivity, gait, and static weight bearing were evaluated.

RESULTS

KHFAC stimulation of the sciatic nerve decreased behavioral evidence of pain and disability. Without KHFAC stimulation, injured animals had heightened tactile sensitivity compared to baseline (p < 0.05), with tactile allodynia reversed during KHFAC stimulation (p < 0.01). Midfoot flexion during locomotion was decreased after injury but improved with KHFAC stimulation (p < 0.05). Animals also placed more weight on their injured limb when KHFAC stimulation was applied (p < 0.05). Electrophysiology measurements at end point showed decreased, but not blocked, compound nerve action potentials with KHFAC stimulation (p < 0.05).

CONCLUSIONS

KHFAC stimulation decreases hypersensitivity but does not cause additional gait compensations. This supports the idea that KHFAC stimulation applied to a peripheral nerve may be able to treat chronic pain resulting from sciatic nerve root inflammation.

The Invasive Management of Pain: Diagnosis and New Treatment Options

Both the diagnosis and treatment of pain are evolving, especially in interventional approaches. Diagnosis of low back pain combines old and new methodologies, in particular, it involves an expanded role for ultrasound. While low back pain is a common complaint, there are many etiologies to the condition which must be explored before a final diagnosis can be made and treatment planned. Tumors and infections are rarely involved in low back pain but should be ruled out in the initial phase itself since failing to address them early can have devastating consequences. Some invasive treatments seem promising in the management of low back pain. Treating musculoskeletal pain with regenerative medicine, such as platelet-rich plasma, holds great promise. Autologous blood products are safe and may help stimulate the body's own responses for regeneration. The so-called "orthobiologics" play a role in sports medicine and the treatment of musculoskeletal pain. Neuromodulation, especially spinal cord stimulation, is undergoing a renaissance with new waveforms, devices, and a greater albeit incomplete understanding of its mechanisms of action. Spinal cord stimulation is not a first-line therapy and not all patients or all back problems respond to this treatment. Nevertheless, the therapy can be safe, effective, and cost-effective with appropriate patient selection. Radiofrequency ablation of nerves in the form of neurotomy can be effective in reducing the pain of osteoarthritis. These procedures, including the newer cooled radiofrequency neurotomy, can restore function, reduce pain, and may potentially have an opioid-sparing effect. Technical expertise in nerve and anatomy is needed for the use of this technique. This review article aims to provide updated information on some invasive intervention techniques in pain management.

Migration of Epidural Leads During Spinal Cord Stimulator Trials

Objective

Lead migration is the most commonly reported complication of spinal cord stimulation (SCS) procedures and lead migration during trials of SCS can compromise both the success of the trial as well as the efficacy of subsequent implantation. Our objective was to examine the incidence and degree of intra-trial SCS lead migration and our hypothesis was that there would be a higher rate of significant radiographic lead migration during SCS trial than what has been previously published for permanently implanted leads.

Materials and Methods

We retrospectively assessed the radiographic location of SCS leads on final fluoroscopic imaging at the time of trial lead placement compared to thoracic radiographs obtained at the end of the SCS trial to quantify the rate and degree of migration during the trial. Thirty-five patients were included in the study with 69 leads assessed for radiographic degree of migration. The majority of patients were trialed utilizing paresthesia-free systems (57%) and the most common indication was for post-laminectomy syndrome (57%).

Results

In our series of 35 patients, on average there was 28 mm or 1.17 vertebral body levels of migration. No statistically significant correlation was found between fixation technique, physician experience, device manufacturer, patient age, sex, height or BMI and likelihood of significant radiographic migration.

Conclusion

In our study, lead migration appears to be a more significant occurrence during SCS trial than previously reported. Intra-trial migration presents a significant challenge for clinical care and examination of risk factors for migration and techniques for prevention are warranted.

Incidence and Risk Factors for Spinal Cord Stimulator Lead Migration With or Without Loss of Efficacy: A Retrospective Review of 91 Consecutive Thoracic Lead Implants

OBJECTIVE

Lead migration after spinal cord stimulator (SCS) implant is a commonly reported complication and the most common reason for revision surgery in cases of loss of efficacy. The primary aims of this study are to describe the incidence and degree of lead migration in the subacute postoperative period after SCS implant and to report potential risk factors for lead migration.

MATERIALS AND METHODS

We performed a retrospective chart review of all patients at a single academic center who received an SCS implant from January 1, 2020, to December 31, 2020. Information on patient (age, sex, weight, and height) and operative factors (device manufacturer, epidural access level and method, and implantable pulse generator location) were extracted from medical records. Intraoperative imaging was compared to subacute follow-up imaging obtained less than 20 days postimplant to measure lead migration distance. Regression models were fitted to determine associations between lead migration distance and potential clinical risk factors.

RESULTS

A total of 91 cases (182 leads) were included in the study. Within 20 days of implantation, 88.5% of leads had migrated (86.3% caudal and 2.2% cephalad). Mean migration distance for leads with caudal migration only was 12.34 ± 12.19 mm based on anteroposterior radiographs and 16.95 ± 15.68 mm on lateral radiographs. There was an association of greater caudal lead migration as patient body mass index increased (β-coefficient 0.07 [95% confidence interval 0.01-0.13], p = 0.031). Within the entire cohort, one patient (1.1%) required lead revision for loss of efficacy.

CONCLUSIONS

In the subacute postoperative period after SCS implant, the majority of SCS leads migrated caudally with an average of two lead contacts. Knowledge of this expected migration and risk factors can better inform implanting physicians intraoperatively when deciding final lead placement location. The finding of high likelihood of caudal lead migration in the subacute postoperative period brings the need for a well-designed prospective study to the forefront of our field. This will allow implanting providers to make well-informed decisions for intraoperative lead placement.

Lead Migration in Neuromodulation

We describe a simple technique of securing surgically implanted leads for spinal cord (SCS), dorsal root ganglion (DRG) and occipital nerve stimulation (ONS), for both primary surgical implantation and correcting lead migration. This technique could also be adapted for securing percutaneously implanted leads. Thirty-nine patients underwent neurosurgical implantation of SCS, DRG, and ONS devices utilizing titanium mini-plates to obtain secure anchorage of leads to adjacent laminae close to their exit point from the epidural space, thereby minimizing the risk of further lead migration or electrode displacement. There were no cases of primary or recurrent lead migration in any patient undergoing lead placement using mini-plate anchorage. The technique appears to offer a reliable means of preventing post-operative lead migration in a variety of spinal and extra-cranial neuromodulation implants.

Partial high frequency nerve block decreases neuropathic signaling following chronic sciatic nerve constriction injury

OBJECTIVE

High frequency (HF) block can quickly and reversibly stop nerve conduction. We hypothesized HF block at the sciatic nerve would minimize nociception by preventing neuropathic signals from reaching the central nervous system.

APPROACH

Lewis rats were implanted with a constriction cuff and a distal cuff electrode around their right sciatic nerve. Tactile sensitivity was evaluated using the 50% paw withdrawal threshold determined using Chaplan's method for von Frey monofilaments. Over the course of 49 days, the 50% paw withdrawal threshold was measured 1) before HF block, 2) during HF block (50 kHz, 3 Vpp), and 3) after HF block. Gait was observed and scored before and during block. At end point, HF block efficacy was directly evaluated using additional cuff electrodes to elicit and record compound neural action potentials across the HF blocking cuff.

MAIN RESULTS

At days 7 and 14 days post-operation, tactile sensitivity was significantly lower during HF block compared to before and after block (p < 0.005). Additionally, an increase in gait disability was not visually observed during HF block.

SIGNIFICANCE

HF block can reduce tactile sensitivity in a limb with a neuropthic injury in a rapidly reversible fashion.

A Retrospective Case Series of a Novel Spinal Cord Stimulator Trial Technique with Less Displacement and Migration of the Trial Leads

Background

Spinal cord stimulation is an established treatment option for certain chronic pain conditions which have been previously unresponsive to conservative therapies or potentially for a subset of patients who have not improved following spine surgery. Prior to permanent lead implantation, stimulator lead trials are performed to ensure adequate patient benefit. During these trials, one of the most common complications and reasons for failure is the displacement and migration of the trial leads, resulting in lost therapeutic coverage. Other complications include infection and dislodged bulky dressings. There is a paucity of literature describing an adequate procedural method to prevent these common complications.

Objective

This study utilizes a series of 19 patients to evaluate a new technique for securing percutaneous spinal cord simulator trial leads, which may minimize dislodgement and migration complications and improve the rate of trial success.

Study Design

Retrospective case series.

Setting

New Jersey Medical School, Department of Anesthesiology, Pain Management Division.

Methods

A retrospective chart review was conducted on 19 consecutive patients undergoing placement of the percutaneous thoracic spinal cord stimulator trial leads for pain associated with lumbar spine pathology over a two-year period (2010–2012).

Results

Of the 19 patients in our cohort, there was one trial lead displacement, no lead migrations, and no site infections. Thirteen patients went on to permanent lead implantation. This improved trial lead placement technique had a high success rate with a low number of complications.

Limitations

Small sample size, retrospective case series, and no control group for comparison.

Conclusion

This case series was able to demonstrate that our described novel spinal cord stimulator trial lead placement and dressing technique can decrease the incidence of lead displacement and migration, thus improving trial success.

Cephalad Lead Migration During a Spinal Cord Stimulation Trial: A Case Presentation

Spinal cord stimulation is used in the treatment of a variety of pain conditions. Lead migration is among the most common complications associated with spinal cord stimulation. Although there have been reports of caudal lead migration, there have been no reports of significant cephalad lead migration during a spinal cord stimulation trial. Here we report what is potentially the first case of significant cephalad lead migration (from the initial T8 position to C2) during a spinal cord stimulation trial. This case demonstrates that significant lead migration is possible, and this case highlights the importance of adequately securing leads during a trial.

LEVEL OF EVIDENCE

V.