Risk Factors and Survival Analysis of Spinal Cord Stimulator Explantation

Implanted Pulse Generators in Lower Extremity Neuroprostheses: A 25-Year Review

OBJECTIVES

Neuroprosthetic devices can improve quality of life by providing an alternative option for motor function lost after spinal cord injury, stroke, and other central nervous system disorders. The objective of this study is to analyze the outcomes of implanted pulse generators that our research group installed in volunteers with paralysis to assist with lower extremity function over a 25-year period, specifically, to determine survival rates and common modes of malfunction, reasons for removal or revision, and precipitating factors or external events that may have adversely influenced device performance.

MATERIALS AND METHODS

Our implantable receiver-stimulator (IRS-8) and implantable stimulator-telemeter (IST-12 and IST-16) device histories were retrospectively reviewed through surgical notes, regulatory documentation, and manufacturing records from 1996 to 2021.

RESULTS

Most of the 65 devices (64.6%) implanted in 43 volunteers remain implanted and operational. Seven underwent explantation owing to infection; seven had internal failures, and six were physically broken by external events. Of the 22 devices explanted, 15 were successfully replaced to restore recipients' enhanced functionality. There were no instances of sepsis or major health complications. The five infections that followed all 93 IRS and IST lower extremity research surgeries during this period indicate a pooled infection rate of 5.4%. The Kaplan-Meier analysis of technical malfunctions between the implant date and most recent follow-up shows five-, ten-, and 20-year device survival rates of 92%, 84%, and 71%, respectively.

CONCLUSIONS

Incidence of malfunction is similar to, whereas infection rates are slightly higher than, other commonly implanted medical devices. Future investigations will focus on infection prevention, modifying techniques on the basis of recipient demographics, lifestyle factors, and education, and integrating similar experience of motor neuroprostheses used in other applications.

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.

Healthcare Economics of High Frequency Spinal Cord Stimulation for Painful Diabetic Peripheral Neuropathy

BACKGROUND

Painful diabetic peripheral neuropathy (pDPN) is a debilitating complication of long-term diabetes. High-frequency spinal cord stimulation (HF-SCS) was recently shown to be an effective treatment option, but the associated healthcare resource utilization (HCRU) on real-world patient populations with pDPN is unknown.

METHODS

Using IBM MarketScan databases, we identified patients with HF-SCS implantation between January 2016 and December 2019 who had a diagnosis of diabetes or diabetic neuropathy within two years before implant. Cost data were collected for the six months before HF-SCS implantation (baseline) and for the periods of one, three, and six months post-implantation. The six-month explant rate was calculated.

RESULTS

A total of 132 patients met inclusion criteria. The median total cost at baseline was $19 220 and was $1356 at one month post-implant, $4858 at three months post-implant, and $13 305 at six months post-implant. The median baseline out-of-pocket cost was $1477 and was $710 at six months post-implant. The average total cost reduction from baseline to six months post-implant was $5118 (P < .001), or $853 per month. The median device acquisition cost was $35 755. The explant rate within six months was 2.1%.

CONCLUSIONS

High frequency spinal cord stimulation significantly reduces total HCRU in patients with pDPN, and based on the average monthly cost reduction of $853, we estimate that the therapy recoups acquisition costs within 3.5 years. As policy increasingly focuses on value-based care, it will be critical to consider the cost and outcomes of innovative therapies.

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.

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.

Treating Chronic, Intractable Pain with a Miniaturized Spinal Cord Stimulation System: 1-Year Outcomes from the AUS-nPower Study During the COVID-19 Pandemic

Purpose

Spinal cord stimulation (SCS) is a highly effective treatment for chronic neuropathic pain. Despite recent advances in technology, treatment gaps remain. A small SCS system with a miniaturized implantable pulse generator (micro-IPG; <1.5 cm3 in volume) and an externally worn power source may be preferred by patients who do not want a large, implanted battery. We report here the long-term outcomes from the first-in-human study evaluating the safety and performance of a new neurostimulation system.

Patients and Methods

This was a prospective, multi-center, open-label, single-arm study to evaluate this SCS system, in the treatment of chronic, intractable leg and low-back pain. Consented subjects who passed screening continued on to the long-term phase of the study. One-year, patient-reported outcomes (PRO's) such as pain (Numeric Rating Scale, NRS), functional disability, quality of life, and mood were captured.

Results

Twenty-six (26) evaluable subjects with permanent implants were included in this analysis. The average leg pain NRS score decreased from 6.8 ± 1.2 at baseline to 1.1 ± 1.2 at the end of the study (p < 0.001), while the average low-back pain NRS score decreased from 6.8 ± 1.2 to 1.5 ± 1.2 (p < 0.001). The responder rate (proportion with ≥50% pain relief) was 91% in the leg(s) and 82% in the low back. There were significant improvements in functional disability (Oswestry Disability Index) and in mood (Beck Depression Inventory), demonstrating a 46% and 62% improvement, respectively (p < 0.001). Eleven-point Likert scales demonstrated the wearable to be very comfortable and very easy to use.

Conclusion

There were considerable challenges conducting a clinical study during the COVID-19 pandemic, such as missed study programming visits. Nevertheless, subjects had significant PRO improvements through 1-year. The small size of the implanted device, along with a proprietary waveform, may allow for improved SCS outcomes and a drop in incidence of IPG-pocket pain.

Spinal Cord Stimulation for Painful Diabetic Neuropathy

Spinal cord stimulation (SCS) technology has been recently approved by the US Food and Drug Administration (FDA) for painful diabetic neuropathy (PDN). The treatment involves surgical implantation of electrodes and a power source that delivers electrical current to the spinal cord. This treatment decreases the perception of pain in many chronic pain conditions, such as PDN. The number of patients with PDN treated with SCS and the amount of data describing their outcomes is expected to increase given four factors: (1) the large number of patients with this diagnosis, (2) the poor results that have been obtained for pain relief with pharmacotherapy and noninvasive non-pharmacotherapy, (3) the results to date with investigational SCS technology, and (4) the recent FDA approval of systems that deliver this treatment. Whereas traditional SCS replaces pain with paresthesias, a new form of SCS, called high-frequency 10-kHz SCS, first used for pain in 2015, can relieve PDN pain without causing paresthesias, although not all patients experience pain relief by SCS. This article describes (1) an overview of SCS technology, (2) the use of SCS for diseases other than diabetes, (3) the use of SCS for PDN, (4) a comparison of high-frequency 10-kHz and traditional SCS for PDN, (5) other SCS technology for PDN, (6) deployment of SCS systems, (7) barriers to the use of SCS for PDN, (8) risks of SCS technology, (9) current recommendations for using SCS for PDN, and (10) future developments in SCS.

Short-Term Health Care Costs of High-Frequency Spinal Cord Stimulation for the Treatment of Postsurgical Persistent Spinal Pain Syndrome

OBJECTIVE

High-frequency spinal cord stimulation (HF-SCS) is a treatment option for postsurgical persistent spinal pain syndrome (type 2 PSPS). We aimed to determine the health care costs associated with this therapy in a nationwide cohort.

MATERIALS AND METHODS

IBM Marketscan® Research Databases were used to identify patients who underwent HF-SCS implantation from 2016 to 2019. Inclusion criteria included prior spine surgery or diagnoses of PSPS or postlaminectomy pain syndrome any time within the two years before implantation. Inpatient and outpatient service costs, medication costs, and out-of-pocket costs were collected six months before implantation (baseline) and one, three, and six months after implantation. The six-month explant rate was calculated. Costs were compared between baseline and six months after implant via Wilcoxon sign rank test.

RESULTS

In total, 332 patients were included. At baseline, patients incurred median total costs of $15,393 (Q1: $9,266, Q3: $26,216), whereas the postimplant median total costs excluding device acquisition were $727 (Q1: $309, Q3: $1,765) at one month, $2,840 (Q1: $1,170, Q3: $6,026) at three months, and $6,380 (Q1: $2,805, Q3: $12,637) at six months. The average total cost was reduced from $21,410 (SD $21,230) from baseline to $14,312 (SD $25,687) at six months after implant for an average reduction of $7,237 (95% CI = $3212-$10,777, p < 0.001). The median device acquisition costs were $42,937 (Q1: $30,102, Q3: $65,880). The explant rate within six months was 3.4% (8/234).

CONCLUSIONS

HF-SCS for PSPS was associated with significant decreases in total health care costs and offsets acquisition costs within 2.4 years. With the rising incidence of PSPS, it will be critical to use clinically effective and cost-efficient therapies for treatment.

Remote Management of Spinal Cord Stimulation Devices for Chronic Pain: Expert Recommendations on Best Practices for Proper Utilization and Future Considerations

OBJECTIVE

Emerging spinal cord stimulation (SCS) remote monitoring and programming technologies provide a unique opportunity to address challenges of in-person visits and improve patient care, although clinical guidance on implementation is needed. The goal of this document is to establish best clinical practices for integration of remote device management into the care of patients with SCS, including remote monitoring and remote programming.

MATERIALS AND METHODS

A panel of experts in SCS met in July 2022, and additional experts contributed to the development of recommendations after the meeting via survey responses and correspondence.

RESULTS

Major goals of remote SCS device management were identified, including prompt identification and resolution of SCS-related issues. The panel identified metrics for remote monitoring and classified them into three categories: device-related (eg, stimulation usage); measurable physiologic or disease-related (eg, patient physical activity or pedometry); and patient-reported (eg, sleep quality and pain intensity). Recommendations were made for frequency of reviewing remote monitoring metrics, although providers should tailor follow-up to individual patient needs. Such periodic reviews of remote monitoring metrics would occur separately from automatic monitoring system notifications (if key metrics fall outside an acceptable range). The guidelines were developed in consideration of reimbursement processes, privacy concerns, and the responsibilities of the care team, industry professionals, manufacturers, patients, and caregivers. Both existing and needed clinical evidence were covered, including outcomes of interest for future studies.

CONCLUSIONS

Given the expansion of SCS device capabilities, this document provides critical guidance on best practices for using remote device management, although medical necessity should drive all remote monitoring decisions, with individualized patient care. The authors also describe the potential of these emerging technologies to improve outcomes for patients with SCS, although more clinical evidence is needed.

Explantation and Simultaneous Explantation-Reimplantation of Spinal Cord Stimulation Paddle Electrodes: Complication Rate and Predisposing Factors

BACKGROUND AND OBJECTIVES

Spinal cord stimulation (SCS) is an effective treatment for chronic pain that does not respond to conservative treatment. Nonetheless, up to 38% of all implanted SCS electrodes are explanted, and while the risks involved in the surgical implantation of SCS paddle electrodes are well documented, there is scarce information about SCS explantations and their associated complications. We aimed to document the complication rate and identify their predisposing factors in SCS paddle electrode explantations and simultaneous explantation-reimplantations.

METHODS

We retrospectively reviewed the outcomes and the characteristics of all patients who underwent explantation of surgically implanted SCS paddle electrodes at the Helsinki University Hospital Department of Neurosurgery between February 2005 and October 2020.

RESULTS

One hundred thirty-one explantations were performed on 106 patients. The complication rate was 18.3% (24 operations). Major complications occurred during 5 operations (3.8%). No permanent neurological deficits were recorded. Smoking predisposed patients to postoperative complications (P = .023). On average, patients who suffered complications required a day longer hospitalization (2.22 vs 2.92, P = .011). Patients who had repeated explantations (3 or more) suffered significantly more complications than patients who had only 1 or 2 operations (62.5% vs 15.4%, P = .005).

CONCLUSION

Our results suggest that the explantation of the SCS paddle electrode is a relatively safe surgical procedure. Although severe complications occurred, they were successfully managed. Repeated explantations should be treated cautiously as they seem to increase the complication rate considerably.

Spinal Cord Stimulation Efficacy and Erroneous Conclusions of the Cochrane Library Review of Spinal Cord Stimulation for Low Back Pain by Traeger et al

Neuromodulation, through the use of spinal cord stimulation, is an evolving therapeutic alternative for the management of chronic and refractory pain [...].

Health Care Resource Utilization of High-Frequency Spinal Cord Stimulation for Treatment of Chronic Refractory Low Back Pain

INTRODUCTION

Chronic refractory low back pain (CRLBP) is a diagnosis characterized by chronic low back pain in patients who are poor candidates for surgery and fail conservative management. High-frequency spinal cord stimulation (HF-SCS) is a new advance in neuromodulation that may be effective in treating these patients. However, the cost burden of this therapy is yet undetermined.

MATERIALS AND METHODS

IBM MarketScan® (IBM, Armonk, NY) data bases were used to retrospectively identify patients with HF-SCS implantation between 2016 and 2019 in the United States. Those with low back pain diagnosis without history of surgery were included in the cohort. Cost data, including inpatient and outpatient service, medication, and out-of-pocket costs, were collected at six months before HF-SCS implantation and one, three, and six months after implantation. The explant rate within six months was evaluated.

RESULTS

A total of 119 patients met the inclusion criteria. Most patients were female (73.1%) and owned commercial insurance (83.2%). Common comorbidities included inflammatory arthritis (22.7%), depression (26.1%), hypertension (44.5%), and obesity (26.1%). In the six months before HF-SCS implantation, patients incurred median total costs of $15,766 (first quartile [Q1]: $8,847; third quartile [Q3]: $24,947), whereas the postimplant median total cost excluding device acquisition was $398 (Q1: $145, Q3: $1,272) at one month, $2,569 (Q1: $823, Q3: $5,266) at three months, and $5,840 (Q1: $2,160; Q3: $14,607) at six months. The average reduction in total cost was $6,914 (95% CI: $588, $12,458, p < 0.001). The median total acquisition cost was $43,586 (Q1: $29,506, Q3: $69,426), with most coming from outpatient services. Of 88 patients with six-month continuous enrollment, two (2.3%) had device explant.

CONCLUSIONS

We present an analysis using large claims data bases of the cost of HF-SCS for treating CRLBP and show that it may be associated with a significant decrease in total health care costs, offsetting device acquisition costs in 27 months. As advances in neuromodulation expand therapy options for patients, it will be important to understand their financial implications.

Efficacy of Spinal Cord Stimulation for Failed Back Surgery Syndrome in Elderly Patients: A Retrospective Study

Objectives

Failed back surgery syndrome (FBSS) refers to a condition where symptoms such as low back pain, leg pain, and numbness persist or recur after lumbar surgery; it has been reported to occur in 10%-40% of patients who have undergone lumbar surgery. Spinal cord stimulation (SCS) has been reported useful for low back and leg pain due to FBSS. In this study, we studied the efficacy and safety of SCS for FBSS in older adults.

Methods

Among FBSS patients who underwent an SCS trial between November 2017 and December 2020, those with at least 50% pain reduction during the trial phase who requested spinal cord stimulator implantation underwent implantation of a stimulator under local anesthesia. The patients were divided into two groups: patients aged <75 years (<75-year-old group) and patients aged ≥75 years (≥75-year-old group). The male/female ratio, symptom duration, operative duration, visual analog scale (VAS) scores before and after one year of surgery, responder rate (RR), complications one year after surgery, and stimulator removal rate were analyzed.

Results

There were 27 cases in the <75-year-old group and 46 in the ≥75-year-old group, with no significant differences in male/female ratio, duration of pain, or operative time between the two groups. VAS scores for low back pain, leg pain, and overall pain one year after surgery were improved significantly from respective preoperative scores in both groups (P < 0.001). There were no significant differences in low back pain VAS, leg pain VAS, overall pain VAS, RR, complications one year after surgery, or stimulator removal rate between the two groups.

Conclusion

SCS reduced pain effectively in both <75-year-old and ≥75-year-old groups with no differences in complications. Therefore, spinal cord stimulator implantation was considered a viable option for FBSS treatment in older adults because it can be performed under local anesthesia and is associated with a low incidence of complications.

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.

An Advanced Practice Provider Guide to Peripheral Nerve Stimulation

Objective

To describe the team approach of an interventional pain management practice, with particular emphasis on advanced practice providers (APPs), in the selection, education, care, and management of peripheral nerve stimulation (PNS) patients.

Materials and Methods

We devised an APP guide to PNS based on an in-depth search of multiple databases for studies on neuromodulation, pain management, and APPs.

Results

Of 65 articles captured in the search strategy, three articles were pertinent to the topic of APP involvement in neuromodulation. More specifically, only one of the three publications on neuromodulation discussed APP involvement in PNS. This single publication was from 1995 and focused on electrical stimulation of the trigeminal ganglion using a permanent percutaneously placed electrode.

Conclusion

PNS is growing in clinical indication and use for both acute and chronic pain conditions. With the increasing need for APPs in both general and specialty medicine, it is imperative that APPs are well educated on PNS. Here, we have outlined ways in which APPs can optimize the care of PNS patients and how the skillset of the APP in a PNS practice can potentially improve patient outcomes.

Evaluation of Sagittal Spinopelvic Balance in Spinal Cord Stimulator Patients

OBJECTIVE

Spinal cord stimulation (SCS) has become a popular nonopioid pain intervention. However, the treatment failure rate for SCS remains significantly high and many of these patients have poor sagittal spinopelvic balance, which has been found to correlate with increased pain and decreased quality of life. The purpose of this study was to determine if poor sagittal alignment is correlated with SCS treatment failure.

MATERIALS AND METHODS

Comparative retrospective analysis was performed between two cohorts of patients who had undergone SCS placement, those who had either subsequent removal of their SCS system (representing a treatment failure cohort) and those that underwent generator replacement (representing a successful treatment cohort). The electronic medical record was used to collect demographic and surgical characteristics, which included radiographic measurements of lumbar lordosis (LL), pelvic incidence (PI), pelvic tilt (PT), and sacral slope (SS). Also included were data on pain medication usage including opioid and nonopioid therapies.

RESULTS

Eighty-one patients met inclusion criteria, 31 had complete removal, and 50 had generator replacements. Measurement of sagittal balance parameters demonstrated that many patients had poor alignment, with 34 outside normal range for LL (10 vs 24 in removal and replacement cohorts, respectively), 30 for PI (12 [38.7%] vs 18 [36.0%]), 46 for PT (18 [58.1%] vs 28 [56.0%]), 38 for SS (18 [58.1%] vs 20 [40.0%]), and 39 for PI-LL mismatch (14 [45.2%] vs 25 [50.0%]). There were no significant differences in sagittal alignment parameters between the two cohorts.

CONCLUSIONS

This retrospective cohort analysis of SCS patients did not demonstrate any relationship between poor sagittal alignment and failure of SCS therapy. Further studies of larger databases should be performed to determine how many patients ultimately go on to have additional structural spinal surgery after failure of SCS and whether or not those patients go on to have positive outcomes.

Explantation of 10 kHz Spinal Cord Stimulation Devices: A Retrospective Review of 744 Patients Followed for at Least 12 Months

OBJECTIVES

High-frequency 10 kHz spinal cord stimulation (10 kHz-SCS) has achieved analgesia superior to traditional SCS in a number of studies. However, there is concern regarding long-term outcomes of 10 kHz-SCS. Prior work has suggested that explant rates are higher with 10 kHz-SCS. Our primary objective was to determine the explant rate of 10 kHz-SCS in a large patient cohort from multiple centers followed for at least 12 months after implant surgery.

MATERIALS AND METHODS

We performed a retrospective chart review of all patients who received a 10 kHz-SCS implant before July 1, 2019. We abstracted patient demographics, implant date, primary site of pain, implant indication, explant date, and reason for explant. A total of 744 patients were included in the study analysis.

RESULTS

Average age of the overall cohort was 65.53 years and 407 (54.7%) were women. Average follow-up for all patients was 793 days. There were a total of 76 explants (10.2%). The most common reason for explant was loss of efficacy, which accounted for 39 explants (51.3% of total explants, 5.2% of overall cohort). Female sex and radiculopathy as the SCS indication were associated with statistically significant decreased risk of 10 kHz-SCS explant.

CONCLUSIONS

We found 10 kHz-SCS explant rates to be similar to prior reported explant rates for traditional SCS devices. Patient-related factors including female sex and radiculopathy as the primary SCS indication may be protective factors against explantation.

Higher Preimplantation Opioid Doses Associated With Long-Term Spinal Cord Stimulation Failure in 211 Patients With Failed Back Surgery Syndrome

Objective

Spinal cord stimulation (SCS) is an effective treatment in failed back surgery syndrome (FBSS). We studied the effect of preimplantation opioid use on SCS outcome and the effect of SCS on opioid use during a two‐year follow‐up period.

Materials and methods

The study cohort included 211 consecutive FBSS patients who underwent an SCS trial from January 1997 to March 2014. Participants were divided into groups, which were as follows: 1) SCS trial only (n = 47), 2) successful SCS (implanted and in use throughout the two‐year follow‐up period, n = 131), and 3) unsuccessful SCS (implanted but later explanted or revised due to inadequate pain relief, n = 29). Patients who underwent explantation for other reasons (n = 4) were excluded. Opioid purchase data from January 1995 to March 2016 were retrieved from national registries.

Results

Higher preimplantation opioid doses associated with unsuccessful SCS (ROC: AUC = 0.66, p = 0.009), with 35 morphine milligram equivalents (MME)/day as the optimal cutoff value. All opioids were discontinued in 23% of patients with successful SCS, but in none of the patients with unsuccessful SCS (p = 0.004). Strong opioids were discontinued in 39% of patients with successful SCS, but in none of the patients with unsuccessful SCS (p = 0.04). Mean opioid dose escalated from 18 ± 4 MME/day to 36 ± 6 MME/day with successful SCS and from 22 ± 8 MME/day to 82 ± 21 MME/day with unsuccessful SCS (p < 0.001).

Conclusions

Higher preimplantation opioid doses were associated with SCS failure, suggesting the need for opioid tapering before implantation. With continuous SCS therapy and no explantation or revision due to inadequate pain relief, 39% of FBSS patients discontinued strong opioids, and 23% discontinued all opioids. This indicates that SCS should be considered before detrimental dose escalation.