Machine learning predicts spinal cord stimulation surgery outcomes and reveals novel neural markers for chronic pain

Spinal cord stimulation (SCS) is a well-accepted therapy for refractory chronic pain. However, predicting responders remain a challenge due to a lack of objective pain biomarkers. The present study applies machine learning to predict which patients will respond to SCS based on intraoperative electroencephalogram (EEG) data and recognized outcome measures. The study included 20 chronic pain patients who were undergoing SCS surgery. During intraoperative monitoring, EEG signals were recorded under SCS OFF (baseline) and ON conditions, including tonic and high density (HD) stimulation. Once spectral EEG features were extracted during offline analysis, principal component analysis (PCA) and a recursive feature elimination approach were used for feature selection. A subset of EEG features, clinical characteristics of the patients and preoperative patient reported outcome measures (PROMs) were used to build a predictive model. Responders and nonresponders were grouped based on 50% reduction in 3-month postoperative Numeric Rating Scale (NRS) scores. The two groups had no statistically significant differences with respect to demographics (including age, diagnosis, and pain location) or PROMs, except for the postoperative NRS (worst pain: p = 0.028; average pain: p < 0.001) and Oswestry Disability Index scores (ODI, p = 0.030). Alpha-theta peak power ratio differed significantly between CP3-CP4 and T3-T4 (p = 0.019), with the lowest activity in CP3-CP4 during tonic stimulation. The decision tree model performed best, achieving 88.2% accuracy, an F1 score of 0.857, and an area under the curve (AUC) of the receiver operating characteristic (ROC)  of 0.879. Our findings suggest that combination of subjective self-reports, intraoperatively obtained EEGs, and well-designed machine learning algorithms might be potentially used to distinguish responders and nonresponders. Machine and deep learning hold enormous potential to predict patient responses to SCS therapy resulting in refined patient selection and improved patient outcomes.

Pain medication tapering for patients with Persistent Spinal Pain Syndrome Type II, treated with Spinal Cord Stimulation: A RCT-study protocol of the PIANISSIMO study

BACKGROUND

Spinal Cord Stimulation (SCS) may provide pain relief in patients with therapy-refractory Persistent Spinal Pain Syndrome Type II (PSPS-T2). Despite the evidence that SCS can reduce disability and reduce pain medication usage, only 25% of the patients is able to completely omit pain medication usage after 12 months of SCS. To tackle the high burden of patients who consume a lot of pain medication, tapering programs could be initiated before starting a trajectory with SCS. The current objective is to examine whether a pain medication tapering program before SCS alters disability in PSPS-T2 patients compared to no tapering program.

METHODS AND DESIGN

A three-arm, parallel-group multicenter randomized controlled trial will be conducted including 195 patients who will be randomized (1:1:1) to either (a) a standardized pain medication tapering program, (b) a personalized pain medication tapering program, or (c) no tapering program before SCS implantation, all with a follow-up period until 12 months after implantation. The primary outcome is disability. The secondary outcomes are pain intensity, health-related quality of life, participation, domains affected by substance use, anxiety and depression, medication usage, psychological constructs, sleep, symptoms of central sensitization, and healthcare expenditure.

DISCUSSION

Within the PIANISSIMO project we propose a way to reduce the risks of adverse events, medication-induced hyperalgesia, tolerance, and dependence by providing pain medication tapering before SCS. Due to the lack of a commonly accepted in-hospital tapering approach, two different tapering programs will be evaluated in this study. If pain medication tapering programs are deemed to be more effective than no tapering on disability, this would add to the evidence towards an improved patient-centered care model in this patient group and set a clear path to advocate for pain medication tapering before SCS as the new standard treatment guideline for these patients.

TRIAL REGISTRATION

ClinicalTrials.gov NCT05861609. Registered on May 17, 2023.

Emotional and psychosocial function after dorsal column spinal cord stimulator implantation: a systematic review and meta-analysis

BACKGROUND

The efficacy of spinal cord stimulation (SCS) in chronic pain studies is traditionally assessed by pain scores, which do not reflect the multidimensional nature of pain perception. Despite the evidence of SCS's influence on emotional functioning comprehensive assessments of its effect remain lacking.

OBJECTIVE

To assess changes in emotional and psychosocial functioning in patients who underwent SCS implantation for chronic pain.

EVIDENCE REVIEW

Ovid MEDLINE, EMBASE, PsychINFO, Cochrane CENTRAL and Scopus databases were searched for original peer-reviewed publications reporting emotional functioning after SCS. The primary outcomes were a pooled mean difference (MD) in anxiety, depression, global functioning, mental well-being and pain catastrophizing at 12 months. The Grading of Recommendation, Assessment, Development, and Evaluation (GRADE) was used to determine the quality of evidence.

FINDINGS

Thirty-two studies were included in the primary analysis. Statistically significant improvements were observed in anxiety (MD -2.16; 95% CI -2.84 to -1.49; p<0.001), depression (MD -4.66; 95% CI -6.26 to -3.06; p<0.001), global functioning (MD 20.30; 95% CI 14.69 to 25.90; p<0.001), mental well-being (MD 4.95; 95% CI 3.60 to 6.31; p<0.001), and pain catastrophizing (MD -12.09; 95% CI -14.94 to -9.23; p<0.001). Subgroup analyses revealed differences in Global Assessment of Functioning and mental well-being based on study design and in depression based on waveform paradigm.

CONCLUSION

The results highlight the statistically and clinically significant improvements in emotional and psychosocial outcomes in patients with chronic pain undergoing SCS therapy. However, these results need to be interpreted with caution due to the very low certainty of evidence per the GRADE criteria.

PROSPERO REGISTRATION

CRD42023446326.

Spinal cord stimulation may reduce lumbar radiculopathy in the setting of metastatic colon cancer

Cancer pain has a substantial impact on the quality of life and functional capacity with a prevalence of up to 70 % in patients with advanced, metastatic, or terminal disease [1]. The WHO pain ladder has been used in practice to guide cancer pain management. A three-step ladder starts with NSAIDs and non-opioids for mild pain, weak opioids for mild to moderate pain and strong opioids for moderate to severe pain with the use of adjuvant medications such as TCAs and muscle relaxants at any stage for optimization (Fallon et al., Dec 2022) [2] We present a case of a patient with metastatic colon cancer who was admitted for intractable pain crisis and right sided L-5 radiculopathy secondary to epidural metastasis (Figs. 1 and 2). The patient's pain left her bedridden, unable to walk and remained refractory to an escalating intravenous opioid regimen and caudal epidural steroids. The patient subsequently underwent spinal cord stimulation (SCS) trial at level T-7 and achieved >80 % pain relief resulting in a markedly decreased opioid requirement and tremendous recovery of ambulatory function (Fig. 3). After sustained results, a permanent implant was placed at T-8 and patient remains discharged with functional restoration and continued pain improvement (Fig. 4). To our knowledge, this is a novel application of SCS for a refractory pain crisis secondary to a metastatic colon cancer induced radiculopathy presenting with severe functional impairment. As we transition away from opioid use, it is imperative as pain physicians, to investigate the potential of current as an alternative means of cancer pain management: a ubiquitous and challenging clinical conundrum.

Long-Term Outcome in Patients With Spinal Cord Stimulation for Failed Back Surgery Syndrome: A 20-Year Audit of a Single Center

STUDY DESIGN

This is a retrospective, observational study.

INTRODUCTION

Spinal cord stimulation (SCS) has found its application in chronic pain treatment, with failed back surgery syndrome (FBSS) as one of the most important indications. However, to date, little is known about the long-term effectiveness of the treatment. The aim of this study is to analyze retrospectively the long-term outcomes of SCS treatment in a single multidisciplinary pain center on predominant radicular pain, using devices of a single manufacturer.

MATERIALS AND METHODS

Patient data on overall patient satisfaction, pain intensity, and adverse events were retrospectively collected in our clinical practice between January 1998 and January 2018, for 191 patients who received a permanent SCS implant. Secondary health measures included the influence of opioid and nicotine use on pain reduction after therapy.

RESULTS

The trial-to-implant ratio was 93.6%. At a mean follow-up of 10.6 years, 78.5% of the patients were satisfied with the treatment outcome, with a significant pain reduction of an average three points on a Numeric Rating Scale. Opioid and nicotine usage did not have a significant link with the pain reduction one year after the treatment. Furthermore, devices had an average battery lifespan of 8.4 years. A total of 248 revisions were recorded. A total of 24 patients (11.7%) acquired an infection; 7 of 204 patients had an infection during the trial period, 2 of 191 patients had an infection in the first postoperative year, and 15 of 191 patients had an infection after the first year. The average time to infection, if not in the first year, was 10.1 years.

CONCLUSIONS

A successful long-term outcome regarding pain relief in patients with predominant radicular pain due to FBSS is established with SCS therapy.

Research hotspots and trends on spinal cord stimulation for pain treatment: a two-decade bibliometric analysis

Background

Chronic pain poses a significant social burden. Spinal cord stimulation (SCS) is considered to be the most promising treatment for refractory pain. The aim of this study was to summarize the current research hotspots on SCS for pain treatment during the past two decades and to predict the future research trends by bibliometric analysis.

Methods

The literature over the last two decades (2002-2022) which was related to SCS in pain treatment was obtained from the Web of Science Core Collection. Bibliometric analyses were conducted based on the following aspects: (1) Annual publication and citation trends; (2) Annual publication changes of different publication types; (3) Publications and citations/co-citations of different country/institution/journal/author; (4) Citations/co-citation and citation burst analysis of different literature; and (5) Co-occurrence, cluster, thematic map, trend topics, and citation burst analysis of different keywords. (6) Comparison between the United States and Europe. All analyses were performed on CiteSpace, VOSviewer, and R bibliometrix package.

Results

A total of 1,392 articles were included in this study, with an increasing number of publications and citations year by year. The most highly published type of literature was clinical trial. United States was the country with the most publications and citations; Johns Hopkins University was the institution with the most publications; NEUROMODULATION published the most papers; the most published author was Linderoth B; and the most cited paper was published in the PAIN by Kumar K in 2007. The most frequently occurring keywords were "spinal cord stimulation," "neuropathic pain," and "chronic pain," etc.

Conclusion

The positive effect of SCS on pain treatment has continued to arouse the enthusiasm of researchers in this field. Future research should focus on the development of new technologies, innovative applications, and clinical trials for SCS. This study might facilitate researchers to comprehensively understand the overall perspective, research hotspots, and future development trends in this field, as well as seek collaboration with other researchers.

The impact of spinal cord stimulation on opioid utilization in failed back surgery syndrome and spinal surgery naïve patients

Background

Spinal cord stimulation (SCS) has been utilized for failed back surgery syndrome (FBSS) with well-documented improvements in pain and function. However, limited studies have investigated the relationship between spinal surgery, SCS and opioid use outcomes.

Methods

A narrative review utilizing the scale for the quality assessment of narrative review articles (SANRA) methodology looking at trials involving SCS and opiates.

Results

Twenty-six studies met inclusion criteria. Surgery-naïve subjects had the greatest mean opioid dose reduction of 50.39% morphine milliequivalents, and the greatest number of patients who discontinued opioids at 53.72%. No statistical analysis was performed due to heterogeneous data.

Conclusion

SCS has a positive impact on opioid reduction, regardless of prior spinal surgical history. However, due to a lack of homogenous data, a formal conclusion comparing outcomes between spinal surgical histories cannot be drawn. There is an inherent difficulty in evaluating this topic given its complexity and multifactorial origin. Studies would require collaboration between pain physicians, societies and industry. Even then, patient biases such as psychological and expectation would be difficult to account for. This topic remains an ongoing challenge for interventional pain physicians.

A Pilot Study Comparing Algorithmic Adaptive Conventional Stimulation with High-Dose Stimulation in Chronic Pain Patients

INTRODUCTION

Spinal cord stimulation is an effective method of treatment for chronic pain. We previously showed that programming using accelerometry was advantageous for paresthesia-based stimulation. However, programming can be labor intensive.

OBJECTIVE

Here we focus on standardized programming for both accelerometer-based paresthesia-induced programming (termed "shuffle") and high-dose (HD) subthreshold programming with stimulation delivered over the T9-10 interspace.

METHODS

In this prospective cross-over study, patients received 4 weeks of shuffle programming and 4 weeks of HD programming in a randomized order. In both intervals, contacts overlying T9-10 were programmed. Pain scales with measurements of activity and sleep were collected at the end of each study arm and compared with preoperative baseline scores.

RESULTS

Twelve patients were enrolled, with 10 patients completing this study. Compared with baseline, during the HD study period, significant improvements were seen in worst pain of week (P = 0.03) and current pain (P = 0.04) as rated on Numeric Rating Scale scores and walking on the Activity Test (P = 0.012). No difference was seen from baseline compared with shuffle stimulation or in shuffle stimulation compared with HD stimulation.

CONCLUSION

In this pilot study, we demonstrated that HD stimulation at T9-10 is superior to algorithmic programming of paresthesia-based stimulation. These results compared with our previous work with shuffle suggest that paresthesia-based stimulation may necessitate stimulation of additional contact locations and additional programming to optimize. This algorithmic programming of paresthesia-based stimulation continues to warrant exploration.

Recent Trends in Medicare Utilization and Reimbursement for Spinal Cord Stimulators: 2000-2019

OBJECTIVE

Spinal cord stimulators (SCS) allow spine surgeons to provide relief for patients who suffer from chronic pain due to several disorders, such as failed back surgery syndrome, complex regional pain syndrome, and neuropathy. Despite this, there remains a paucity of data regarding the utilization and reimbursement of SCS. Therefore, the purpose of this study is to evaluate the monetary and procedural trends of spinal cord stimulators among the Medicare database from 2000 to 2019.

METHODS

Medicare Part B National Summary Data files, which are publicly available, were used. These files contain data from the years 2000-2019 on all services billed to Medicare within that time frame. Each service is given a Current Procedural Terminology (CPT) code and the number of times that service was performed, as well as the total physician Medicare charges and reimbursements for each service annually are included in that data set. The CPT codes for percutaneous and open placement of spinal cord stimulators were identified: 63650 and 63655, respectively. The total allowed services allowed charges and actual payments were isolated from the data set for each year for each CPT code. The total allowed charges and actual payments for the year were then divided by the total allowed services to find and trend the allowed charges and actual payment for each individual service performed for both percutaneous and open placement of spinal cord stimulators.

RESULTS

There were 992,372 Medicare-approved total percutaneous spinal cord stimulator operations and 99,736 Medicare-approved total open spinal cord stimulator operations from 2000 to 2019. Medicare paid $1.02 billion (2019 U.S. dollars) in reimbursement to physicians for percutaneous spinal cord stimulator operations and nearly $145 million (2019 U.S. dollars) in reimbursement to physicians for open spinal cord stimulator operations. From the years 2000 to 2019, there was an average 21.9% increase annually in Medicare-approved percutaneous spinal stimulator placement operations and a 18.4% increase annually in Medicare-approved open spinal stimulator placement operations. During this time, there was also an average 8.7% increase annually in Medicare reimbursement per each percutaneous spinal stimulator placement operation and a 9.1% increase annually in Medicare reimbursement per each open spinal stimulator placement operation.

CONCLUSIONS

The results of this study show that the number of percutaneous and open procedures have steadily increased from 2000 to 2019. Reimbursement per procedure has also increased steadily over this time. Identifying these trends is important to promote research into costs of these surgeries and ensure adequate resource allocation.

High-Resolution Spinal Motor Mapping Using Thoracic Spinal Cord Stimulation in Patients With Chronic Pain

BACKGROUND

High-resolution spinal cord stimulation (HR-SCS) paddle can stimulate medial-dorsal columns and extend stimulation coverage to the laterally positioned spinal targets.

OBJECTIVE

To investigate the medio-lateral selectivity of an HR-SCS paddle in patients with chronic pain.

METHODS

During standard-of-care spinal cord stimulation (SCS) placement, epidurally evoked electromyography and antidromic dorsal column-evoked potentials were recorded in 12 subjects using an HR-SCS paddle with 8 medio-lateral sites spanning the full epidural width at thoracic T9-12 and a commercial paddle consecutively.

RESULTS

Recruitment maps were aligned with respect to physiological midline which was overlapping with anatomic midline in 10 of 11 cases. Overlapping contacts between the HR-SCS and commercial paddles exhibited similar patterns while HR-SCS demonstrated higher precision targeting of certain dermatomes. Spinal motor maps showed that the lateral contacts triggered stronger responses in medial gastrocnemius, adductor magnus, and tibialis anterior while the medial contacts triggered stronger responses in gluteus maximus and adductor hallucis. The time-locked popliteal fossa responses indicated ipsilateral activation by HR-SCS at the lateral contacts and bilateral activation at the medial contacts with stronger ipsilateral responses.

CONCLUSION

This study is the first to perform high-resolution medio-lateral SCS mapping in patients with chronic pain. These results show promise that HR-SCS may provide additional ipsilateral recruitment within the extremities which improve targeting of focal pain in the lower extremities. Furthermore, this study supports the functional use of intraoperative neuromonitoring as a decision tool to determine physiological midline in thoracic SCS surgeries and provides a full methodological framework.

A case series of new radicular pain following the insertion of spinal cord stimulator

Purpose

Although spinal cord stimulation (SCS) is a safe procedure, equipment-related, biological and neurological complications have been observed in previous research, particularly case reports. No reports of new neuropathic pain in the absence of neurological deficit or positive MRI findings have been described. We detail three cases of new-onset radicular pain in the L5/S1 dermatome following insertion of SCS.

Methods

This was a retrospective case series of three patients. Details of clinical background, indications for SCS and events occurring during insertion and further management were recorded.

Results

All three cases were technically difficult and required multiple epidural entry levels, with repeated passage of the electrode into and within the epidural space. All cases involved accessing epidural space T12/L1 and L1/L2. A possible explanation for the new-onset radicular pain could concern oedema to the conus medullaris, resulting from repeated passage of the electrode at the T12/L1 level. Alternative explanations could be direct trauma to transiting nerve roots, neuroplastic changes resulting in peripheral and central sensitisation and immune-mediated nerve injury.

Conclusion

MRI imaging should be analysed prior to the SCS procedure to identify the level of the conus medullaris, with the aim of avoiding repeated passage of electrodes at that level. Unintended neurological adverse events should be discussed with patients during the consent process. Careful patient selection and psychological screening may also help identify patients who may be unlikely to respond to SCS therapy. Further reporting of new radiculopathic pain following SCS insertion is required to strengthen understanding of its potential causes.

Efficacy of interventions to reduce long term opioid treatment for chronic non-cancer pain: systematic review and meta-analysis

OBJECTIVE

To review interventions to reduce long term opioid treatment in people with chronic non-cancer pain, considering efficacy on dose reduction and discontinuation, pain, function, quality of life, withdrawal symptoms, substance use, and adverse events.

DESIGN

Systematic review and meta-analysis of randomised controlled trials and non-randomised studies of interventions.

DATA SOURCES

Medline, Embase, PsycINFO, CINAHL, and the Cochrane Library searched from inception to July 2021. Reference lists and previous reviews were also searched and experts were contacted.

ELIGIBILITY CRITERIA FOR STUDY SELECTION

Original research in English. Case reports and cross sectional studies were excluded.

DATA EXTRACTION AND SYNTHESIS

Two authors independently selected studies, extracted data, and used the Cochrane risk-of-bias tools for randomised and non-randomised studies (RoB 2 and ROBINS-I). Authors grouped interventions into five categories (pain self-management, complementary and alternative medicine, pharmacological and biomedical devices and interventions, opioid replacement treatment, and deprescription methods), estimated pooled effects using random effects meta-analytical models, and appraised the certainty of evidence using GRADE (grading of recommendations, assessment, development, and evaluation).

RESULTS

Of 166 studies meeting inclusion criteria, 130 (78%) were considered at critical risk of bias and were excluded from the evidence synthesis. Of the 36 included studies, few had comparable treatment arms and sample sizes were generally small. Consequently, the certainty of the evidence was low or very low for more than 90% (41/44) of GRADE outcomes, including for all non-opioid patient outcomes. Despite these limitations, evidence of moderate certainty indicated that interventions to support prescribers' adherence to guidelines increased the likelihood of patients discontinuing opioid treatment (adjusted odds ratio 1.5, 95% confidence interval 1.0 to 2.1), and that these prescriber interventions as well as pain self-management programmes reduced opioid dose more than controls (intervention v control, mean difference -6.8 mg (standard error 1.6) daily oral morphine equivalent, P<0.001; pain programme v control, -14.31 mg daily oral morphine equivalent, 95% confidence interval -21.57 to -7.05).

CONCLUSIONS

Evidence on the reduction of long term opioid treatment for chronic pain continues to be constrained by poor study methodology. Of particular concern is the lack of evidence relating to possible harms. Agreed standards for designing and reporting studies on the reduction of opioid treatment are urgently needed.

REVIEW REGISTRATION

PROSPERO CRD42020140943.

Spinal Cord Stimulation as Treatment for Cancer and Chemotherapy-Induced Pain

Neuropathic pain is a rampant disease exacting a significant toll on patients, providers, and health care systems around the globe. Neuromodulation has been successfully employed to treat many indications including failed back surgery syndrome (FBSS), complex regional pain syndrome (CRPS), phantom limb pain (PLP), radiculopathies, and intractable pelvic pain, among many others. Recent studies have also demonstrated efficacy for cancer-related pain and chemotherapy induced neuropathy with these techniques. Spinal cord stimulation (SCS) is the most commonly employed technique and involves implantation of percutaneous or paddle leads targeting the dorsal columns of the spinal cord with the goal of disrupting the pain signals traveling to the brain. Tonic, high frequency, and burst waveforms have all been shown to reduce pain and disability in chronic pain patients. Closed-loop SCS systems that automatically adjust stimulation parameters based on feedback (such as evoked compound action potentials) are becoming increasingly used to help ease the burden placed on patients to adjust their programming to their pain and position. Additionally, dorsal root ganglion stimulation (DRGS) is a newer technique that allows for dermatomal coverage especially in patients with pain in up to two dermatomes. Regardless of the technique chosen, neuromodulation has been shown to be cost-effective and efficacious and should be given full consideration in patients with chronic pain conditions.

The Role of Spinal Cord Stimulation in Reducing Opioid Use in the Setting of Chronic Neuropathic Pain: A Systematic Review

OBJECTIVE

The aim was to examine research on the impact of spinal cord stimulation (SCS) on the reduction of preimplantation opioid dose and what preimplantation opioid dose is associated with a reduction or discontinuation of opioid use postimplantation.

METHODS

Systematic review of literature from PubMed, Web of Science, and Ovid Medline search of "opioid" and "pain" and "spinal cord stimulator." Inclusion criteria included original research providing data on SCS preimplantation opioid dosing and 12 months postimplantation opioid dosing or that correlated specific preimplantation opioid dose or opioid dose cutoff with significantly increased likelihood of opioid use discontinuation at 12 months postimplantation.

RESULTS

Systematic review of the literature yielded 17 studies providing data on pre-SCS and post-SCS implantation dose and 4 providing data on the preimplantation opioid dose that significantly increased likelihood of opioid use discontinuation at 12 months postimplantation. Data from included studies indicated that SCS is an effective tool in reducing opioid dose from preimplantation levels at 12 months postimplantation. Data preliminarily supports the assertion that initiation of SCS at a preimplantation opioid dose of ≤20 to ≤42.5 morphine milligram equivalents increases the likelihood of postimplantation elimination of opioid use.

DISCUSSION

SCS is an effective treatment for many types of chronic pain and can reduce or eliminate chronic opioid use. Preimplantation opioid dose may impact discontinuation of opioid use postimplantation and the effectiveness of SCS in the relief of chronic pain. More research is needed to support and strengthen clinical recommendations for initiation of SCS use at lower daily opioid dose.

Ethical Considerations in the Implantation of Neuromodulatory Devices

OBJECTIVES

Neuromodulatory devices are increasingly used by neurosurgeons to manage a variety of chronic conditions. Given their potential benefits, it is imperative to create clear ethical guidelines for the use of these devices. We present a tiered ethical framework for neurosurgeon recommendations for the use of neuromodulatory devices.

MATERIALS AND METHODS

We conducted a literature review to identify factors neurosurgeons should consider when choosing to offer a neuromodulatory device to a patient.

RESULTS

Neurosurgeons must weigh reductions in debilitating symptoms, improved functionality, and preserved quality of life against risks for intraoperative complications and adverse events due to stimulation or the device itself. Neurosurgeons must also evaluate whether patients and families will maintain responsibility for the management of neuromodulatory devices. Consideration of these factors should occur on an axis of resource allocation, ranging from provision of neuromodulatory devices to those with greatest potential benefit in resource-limited settings to provision of neuromodulatory devices to all patients with indications in contexts without resource limitations. Neurosurgeons must also take action to promote device effectiveness throughout the duration of care.

CONCLUSIONS

Weighing risks and benefits of providing neuromodulatory devices and assessing ability to remain responsible for the devices on the level of the individual patient indicate which patients are most likely to achieve benefit from these devices. Consideration of these factors on an axis of resource allocation will allow for optimal provision of neuromodulatory devices to patients in settings of varied resources. Neurosurgeons play a primary role in promoting the effectiveness of these devices.

Clinical Outcomes after Spinal Cord Stimulation According to Pain Characteristics

Objective

Spinal cord stimulation (SCS) is an effective treatment for chronic neuropathic pain. However, its clinical efficacy in regard to specific types of pain has not been well studied. The primary objective of this study was to retrospectively analyze the clinical outcomes of paddle-type SCS according to the type of neuropathic pain.

Methods

Seventeen patients who underwent paddle-lead SCS at our hospital were examined. Clinical outcomes were evaluated pre- and postoperatively (3 months, 1 year, and last follow-up) using the Neuropathic Pain Symptom Inventory (NPSI). The NPSI categorizes pain as superficial, deep, paroxysmal, evoked, or dysesthesia and assess the duration of the pain (pain time score). Changes in NPSI scores were compared with change in Visual analogue scale (VAS) scores.

Results

After SCS, the pain time score improved by 45% (independent t-test, p=0.0002) and the deep pain score improved by 58% (independent t-test, p=0.001). Improvements in the pain time score significantly correlated with improvements in the VAS score (r=0.667, p=0.003, Spearman correlation). Additionally, the morphine milligram equivalent value was markedly lower after vs. before surgery (~49 mg, pared t-test, p=0.002). No preoperative value was associated with clinical outcome.

Conclusion

The NPSI is a useful tool for evaluating the therapeutic effects of SCS. Chronic use of a paddle-type spinal cord stimulation improved the deep pain and the pain time scores.

Does Neuromodulation Reduce Chronic Pain Patient Emergency Department Utilization?

BACKGROUND

Chronic pain (CP) affects roughly 100 million adults in the United States. These subjects present disproportionately to the emergency department (ED). Neuromodulation (NM) has been shown to reduce ED visits longitudinally in subjects.

OBJECTIVE

To compare ED utilization rates between subjects with CP with and without NM.

METHODS

Subjects with failed back surgery syndrome, complex regional pain syndrome, or neuropathic pain diagnosis who visited the hospital between January 1, 2019, and December 31, 2019, were included. Subjects were divided into a NM-treated cohort and a non-NM cohort. Demographic information, medications, and pain provider visits were obtained. Pain-related ED visits between 2017 and 2019 were compared.

RESULTS

A total of 2516 subjects were identified; 291 (11.6%) previously underwent NM. The non-NM cohort had significantly higher rate of pain-related ED visits compared with the NM cohort (15.1% vs 10.0%, P = .018). Younger age (odds ratio [OR] = 0.888 [0.843-0.935]), shorter distance to the hospital (OR = 0.807 [0.767-0.849]), lower household income (OR = 0.865 [0.831-0.901]), opioid use (OR = 1.375 [1.291-1.465]), nonopioid use (OR = 1.079 [1.033-1.128]), and non-NM therapy (OR = 1.751 [1.283-2.390]) were significant predictors of ED visits. Opioid use was the only significant predictor (OR = 6.124 [1.417-26.473]) associated with ED visits in the NM cohort.

CONCLUSION

Subjects who underwent NM had fewer visits to the ED when compared with similar subjects who received conventional treatment. Opioid use prompted increased ED utilization in both cohorts. We posit that NM leads to improvement in pain outcomes, integration with multidisciplinary pain specialists, and reduction in severity and frequency of acute pain exacerbations, thereby limiting health care resource utilization.

Procedure-Related Outcomes Including Readmission Following Spinal Cord Stimulator Implant Procedures: A Retrospective Cohort Study

BACKGROUND

Spinal cord stimulation (SCS) has been shown to reduce opioid consumption, reduce pain, improve quality of life compared to conventional therapy, and be more effective than spine reoperation in carefully selected patients. In this study, we evaluate readmissions after SCS implantation procedures, costs, predictors, and etiologies for readmission following implantation procedures.

METHODS

The study was a retrospective cohort using the National Readmissions Database from 2013 to 2017. Administrative billing codes were used to identify patients undergoing SCS implantation procedures. The primary outcome of our study was 30-day readmission following the SCS implantation procedure. Continuous outcomes were compared between groups using the Student t test or Wilcoxon rank sum test. In addition, multivariable predictors of 30-day readmission were assessed by hierarchical logistic regression analysis.

RESULTS

A total of 3737 (26.7% open surgical SCS implants [OS-SCS]) individuals admitted to the hospital for SCS implantation were included in the final cohort analysis. The cohort consisted of predominantly female patients (58.71%) and in the 50- to 64-year age group (35.46%). Patients who underwent open surgical SCS implantation had a longer length of stay during the initial admission and a higher 30-day readmission rate (9.4% vs 7% P = .01). OS-SCS, older age, lower socioeconomic status, patients with specific comorbidities (ie, hypertension or chronic obstructive pulmonary disease [COPD]), and home discharge are associated with readmission.

CONCLUSIONS

Readmission rates after SCS implantation are around 7.7% in the United States. Infection and postoperative complications remain the top etiologies for readmission. Open surgical SCS implantation is associated with more extended initial hospitalization and a higher rate of readmission when compared to percutaneous SCS implantation procedures.

Decreased Opioid Consumption and Durable Pain Relief in Patients Treated with 10 kHz SCS: A Retrospective Analysis of Outcomes from Single-Center

Background

Chronic pain is frequently treated with opioid analgesics, but there is limited evidence for efficacy for chronic use of opioids and the drugs pose significant risks to patients’ physical and mental health. Spinal cord stimulation delivered at a frequency of 10,000 Hertz (10 kHz SCS) is a minimally invasive therapy with demonstrated efficacy and safety in treating chronic pain that has also been associated with decreased opioid use.

Objective

To evaluate opioid reduction and pain relief in real-world cohort.

Study Design

Retrospective review.

Setting

Single center.

Patients and Methods

Consecutive patients who were implanted with 10 kHz SCS devices from December 1, 2015, to June 30, 2020 for the treatment of chronic pain in the trunk or lower limbs were included. Changes in opioid use following 10 kHz SCS treatment were extracted from electronic medical records, and patient-reported pain relief, improvement in function and sleep were extracted from manufacturer’s database. Responder rate was defined as the proportion of patients with at least 50% pain relief. Anonymised results from descriptive analysis of the data are reported.

Results

At last follow-up (median 21.4 months), mean daily opioid dose fell by 48.4 morphine milligram equivalents (MME), and fewer patients used opioids. Mean pain relief in these patients was 57% ± 4%, and responder rate was 68% at last recorded follow-up. Interestingly, pain relief (66%) and responder rate (86%) were higher in patients with 1 year or more. Finally, 50% of patients reported improved sleep, and 73% reported improvement in function at last recorded follow-up after treatment with 10 kHz SCS.

Conclusion

These results support 10 kHz SCS as a safe and effective treatment of chronic pain in real-world patients with secondary benefits to opioid consumption and measures of patients’ quality of life.

Spinal Cord Stimulation via Percutaneous and Open Implantation: Systematic Review and Meta-Analysis Examining Complication Rates

BACKGROUND

Spinal cord stimulation (SCS) has become a successful therapeutic option for combating chronic pain and can be implanted via percutaneous or open (laminotomy/laminectomy) techniques. This study aimed to systematically review the complications that occur after SCS placement via percutaneous and open (laminotomy/laminectomy) in failed back surgery syndrome (FBSS), complex regional pain syndrome (CRPS), and chronic back (lumbosacral)/leg pain.

METHODS

The PubMed and Embase databases were searched from inception to June 2020; prospective studies using SCS in patients with FBSS, CRPS, and chronic low back pain that reported both complications and the implantation method used were included. Effects and results from each study were combined using a random-effects model and were structured for subgroup analysis between open implantation and percutaneous implantation. Meta-regression was performed by calculating a mean difference and weighted by inverse variance and 95% confidence intervals (CIs).

RESULTS

Thirty-two articles were included in this systematic review and meta-analysis. Using several different patient- and event-based metrics, our meta-analysis revealed an overall average complication rate of 21.1% (95% CI, 14.9-27.2). Equipment, technical, and medical complications occurred at rates of 12.1%, 1.1%, and 6.3%, respectively. Lead migration and infection rates were 5.6% and 3.8%, respectively. When comparing the 2 implant techniques, medical-related surgical reinterventions and explants due to infection were more common in open compared with percutaneous SCS procedures.

CONCLUSIONS

Equipment-related complications accounted for the majority of SCS complications. Percutaneous SCS resulted in less reintervention and fewer explants caused by medical-related complications and infection, respectively. These conclusions may provide a general understanding of the SCS complications profile for physicians who care for SCS patients.

Treatment Strategies for Generator Pocket Pain

OBJECTIVE

Generator site pain is a relatively common phenomenon in patients undergoing spinal cord stimulation (SCS) that complicates management and effective pain relief. This pain may be managed conservatively, with repositioning of the battery and, in some cases, with explant. Here we explore our experience with management of generator site pain ("pocket pain") in a large single-center study.

METHODS

All SCS permanent implants and implantable pulse generator (IPG) placements over 9 years were reviewed. Of 785 cases, we identified 43 patients with pocket pain (5.5%). Demographics and treatments of the pocket pain cohort were analyzed.

RESULTS

The mean age (± SEM) of the pocket pain cohort was 46.86 ± 1.06, and there were 10/33 males/females. Females were overrepresented in pocket pain cohort (76.7%) when compared with the total SCS cohort (59.0%) (X2 = 5.93, P = 0.015). Diagnosis included failed back surgery syndrome (51.2%), complex regional pain syndrome (23.3%), and chronic neuropathic pain (25.5%). No patients improved with conservative therapy. All patients either went on to revision (n = 23) or explant (n = 20). Time from initial surgery to development of pocket pain was 7.5 months (range: 0.3-88) and from pocket pain to revision surgery was 4.5 months (range: 0.4-26). In addition, significantly more pocket pain patients (65.1%) had workers' compensation (WC) insurance compared with patients without pocket pain (24.9%) (X2 = 33.3, P < 0.001).

CONCLUSION

In our institutional experience, pocket pain was inadequately managed with conservative treatments. Being female and having SCS filed under WC increased risk of pocket pain. Future work will explore the nuances in device placement based on body shape and manual activity responsibilities.

Systemic Opioid Prescribing Patterns and Total Cost of Care in Patients Initiating Spinal Cord Stimulation Therapy: A Retrospective Analysis

BACKGROUND

Few studies have evaluated patterns of systemic opioid use among patients initiating spinal cord stimulation therapy for chronic pain. This study evaluated systemic opioid discontinuation and/or dose reduction and total health care cost after the start of spinal cord stimulation therapy.

METHODS

Using a commercial insurance claims database (2008-2017), we analyzed opioid utilization patterns in patients initiating spinal cord stimulation therapy over a 1-year baseline and 2-year follow-up. The primary end point was defined as either discontinuation (≥365-day gap between prescription fills or total days' supply in follow-up ≤30 days) or ≥50% reduction in average daily morphine milligram equivalent dose. "Costs" were defined as total payer plus patient out-of-pocket payments.

RESULTS

A total of 5,878 patients met the selection criteria. Of these, 152 (2.6%) showed no opioid prescription data at any point in the study period. Among patients with one or more prescriptions, 42.0% met the primary end point (22.0% discontinued, and 20.0% reduced their dose by 50% or more). Mean total adjusted costs were significantly reduced in years 1 and 2 of follow-up relative to baseline (excluding device insertion costs). The average time to breakeven when accounting for device trial and permanent insertion cost was 3.1 years among those who met the composite end point and 4.2 years among those who did not.

CONCLUSIONS

This analysis shows that among patients who continued spinal cord stimulation therapy for at least 2 years, a significant proportion were able to reduce and/or discontinue systemic opioid use, with costs after the start of therapy significantly reduced relative to baseline.

Long-Term Efficacy of a Novel Spinal Cord Stimulation Clinical Workflow Using Kilohertz Stimulation: Twelve-Month Results From the Vectors Study

BACKGROUND AND OBJECTIVES

Multiple variables play a role in spinal cord stimulation (SCS) treatment outcomes, including patient anatomy, pain pattern, lead location, stimulation parameters, and so on. A wide range of stimulation parameters are considered safe and on-label, and as a result a growing number of new frequencies and frequency-combinations are being incorporated into standard practice. A standardized approach to therapy delivery may provide more consistent outcomes for more patients. The Vectors study evaluated whether there is significant sustained improvement in pain and functional outcomes when therapy is delivered using a standardized approach.

MATERIALS AND METHODS

Vectors, a post-market, single-arm study evaluated the safety and efficacy of SCS with an implantable neurostimulator starting with 1 kHz stimulation, targeting the T9-T10 disc space following paresthesia mapping. Subjects with chronic intractable low back and leg pain (visual analogue scale [VAS] ≥ 50 mm) were enrolled. The primary endpoint was change in overall pain (VAS) at the three-month visit compared to baseline. Subjects were followed through 12 months. Secondary endpoints included changes in low back and leg pain, quality of life (European Quality of Life - Five Dimensions, EQ-5D-5L), disability (Oswestry Disability Index, ODI), individual subject goals, and subject satisfaction.

RESULTS

There was a significant reduction in overall pain (VAS; 45.4 mm) through the three-month visit, which was sustained through 12 months. At 12 months, 79% of subjects had ≥50% improvement in at least one pain domain (overall, lowback or leg) with 85% of subjects reporting therapy satisfaction. There was a decrease in disability and an improvement in quality of life with 70% of subjects achieving a personal activity goal by the three-month visit.

CONCLUSIONS

Long-term pain relief and improvement in quality of life and function were achieved when following a standardized workflow.

CLINICAL TRIAL REGISTRATION

The Clinicaltrials.gov registration number for the study is NCT03345472.

Detoxification of Neuromodulation Eligible Patients by a Standardized Protocol: A Retrospective Pilot Study

OBJECTIVES

Patients eligible for spinal cord stimulation (SCS) generally experience excruciating pain, requiring more opioid consumption, which is usually an indication for SCS implantation. After final implantation, SCS has the ability to stabilize or decrease opioid usage in half of the patients. In this study, opioids were actively eliminated prior to implantation of any neuromodulation device with a standardized detoxification protocol. This pilot study aims to explore the feasibility, effectiveness, and safety of this opioid detoxification protocol prior to neuromodulation techniques.

MATERIALS AND METHODS

In this retrospective pilot study, 70 patients who were taking opioids and who were eligible for neuromodulation techniques, underwent the detoxification program. A combined in- and out-patient clinic protocol was applied, whereby clonidine was the main component of both parts of the program. A multidisciplinary team with pain physicians and psychologists was responsible for performing this detoxification program. Safety and feasibility were systematically recorded during the hospitalization.

RESULTS

No serious safety issues were reported. At the start of the program, patients reported a mild sedative effect of clonidine. Additionally, most patients presented mild symptoms of opioid withdrawal, which were partially countered by the sedative effect of clonidine. Both patients and the medical staff found this protocol feasible in clinical practice. Concerning the effectiveness, a statistically significant decrease in median morphine milligram equivalents (MMEs) was found with a MME of 175 (Q1-Q3: 118.1-240) at baseline and at the last available follow-up visit the MME was 0 (Q1-Q3: 0-16.88).

CONCLUSIONS

This standardized detoxification program has proven its effectiveness, safety, and feasibility in this single-center experience pilot study in patients eligible for neuromodulation techniques.

Impact of Spinal Cord Stimulation on Opioid Dose Reduction: A Nationwide Analysis

BACKGROUND

Opioid misuse in the USA is an epidemic. Utilization of neuromodulation for refractory chronic pain may reduce opioid-related morbidity and mortality, and associated economic costs.

OBJECTIVE

To assess the impact of spinal cord stimulation (SCS) on opioid dose reduction.

METHODS

The IBM MarketScan® database was retrospectively queried for all US patients with a chronic pain diagnosis undergoing SCS between 2010 and 2015. Opioid usage before and after the procedure was quantified as morphine milligram equivalents (MME).

RESULTS

A total of 8497 adult patients undergoing SCS were included. Within 1 yr of the procedure, 60.4% had some reduction in their opioid use, 34.2% moved to a clinically important lower dosage group, and 17.0% weaned off opioids entirely. The proportion of patients who completely weaned off opioids increased with decreasing preprocedure dose, ranging from 5.1% in the >90 MME group to 34.2% in the ≤20 MME group. The following variables were associated with reduced odds of weaning off opioids post procedure: long-term opioid use (odds ratio [OR]: 0.26; 95% CI: 0.21-0.30; P < .001), use of other pain medications (OR: 0.75; 95% CI: 0.65-0.87; P < .001), and obesity (OR: 0.75; 95% CI: 0.60-0.94; P = .01).

CONCLUSION

Patients undergoing SCS were able to reduce opioid usage. Given the potential to reduce the risks of long-term opioid therapy, this study lays the groundwork for efforts that may ultimately push stakeholders to reduce payment and policy barriers to SCS as part of an evidence-based, patient-centered approach to nonopioid solutions for chronic pain.

Association of Outcomes of Spinal Cord Stimulation for Chronic Low Back Pain and Psoas Measurements Based on Size of Iliopsoas Muscles

INTRODUCTION

Patients experience variable long-term improvement in chronic back pain despite successful spinal cord stimulation (SCS) trials. Iliopsoas (IP) size has been shown to differ between patients with low back pain and healthy controls. In this study, we examine whether IP muscle cross-sectional area (CSA) is associated with SCS outcomes.

MATERIALS AND METHODS

We examined patients for whom we had lumbar MRIs 6.3 years prior to SCS and had baseline and one-year outcome data. Percent change from baseline to one year was calculated for Numeric Rating Scale (NRS), Oswestry Disability Index (ODI), Beck Depression Inventory (BDI), Pain Catastrophizing Scale (PCS), and McGill Pain Questionnaire (MPQ). Correlations between IP muscle CSA, ratio of iliopsoas muscle size to the vertebral body area (P/VBA), and the ratio of iliopsoas muscle size to BMI (P/BMI) were examined. Sex differences were considered.

RESULTS

A total of 73 subjects were included in this study including 30 females and 43 males. Males had significantly larger IP (males 15.70 ± 0.58, females 9.72 ± 0.43; p < 0.001), P/VBA (males 1.00 ± 0.04, females 0.76 ± 0.03, p < 0.001) and P/BMI ratio (males 0.51 ± 0.02, females 0.32 ± 0.01; p < 0.001) than females. In females, P/VBA predicted NRS worst pain scores (β = 0.82, p = 0.004, r² = 0.55) and BDI (β = 0.59, p = 0.02, r² = 0.24). In males, P/BMI was a significant predictor of BDI outcomes scores (β = 0.45, p = 0.03, r² = 0.16). Males who had more muscle mass measured by iliopsoas size had more depression as measured using BDI (p = 0.03, r = 0.61). Females with less muscle mass measured by P/VBA also experienced more depression (p = 0.02, r = 0.74).

CONCLUSIONS

Our study showed that psoas measurements correlated with various pain outcomes specifically. P/VBA was most predictive in females and P/BMI in males. Depression correlated with P/BMI, reinforcing the complex relationship between depression and constant chronic pain. Tertile analyses further showed a relationship between iliopsoas CSA and depression in males and females. We provide preliminary data of sex-specific psoas measurements as a risk factor for worse SCS outcomes.

Opioid use and spinal cord stimulation therapy: The long game

Spinal cord stimulation (SCS) has been considered as an alternative therapy to reduce opioid requirements in certain chronic pain disorders. However, information on long-term opioid consumption patterns and their impact on SCS device explantation is lacking. We conducted a retrospective study of 45 patients to characterize long-term patterns of opioid usage after SCS implantation. Daily morphine equivalent dosage (MED) increased, decreased, and remained the same in 40%, 40%, and 20% of patients at 1-year follow-up, respectively. Twelve (27%) underwent explantation due to treatment failure at a median of 18 months after implantation. Pre-operative opioid status (naïve vs. active use) was not associated with explantation (18% vs. 29%, p = 0.699) and neither was the daily MED change status (i.e. increased, decreased, unchanged) at 1-year (p = 0.499, 1.000, 0.735, respectively). Following explantation, reduction in the daily MED was seen in 92% of patients with dosages falling below pre-operative baseline in nine. Among the opioid naïve patients, 55% were on opioids at last follow-up (average 32.4 ± 14.6 months). Our results indicate that daily opioid consumption does not decrease in most patients 1-year after SCS implantation. Furthermore, post-operative evaluation beyond 1-year is necessary to assess the efficacy and durability of SCS therapy as well as its impact on opioid requirement. Lastly, rigorous patient selection and pre-operative risk assessment for misuse and dependence are paramount to improving outcome after SCS implantation.

One-Year Results of Prospective Research Study Using 10 kHz Spinal Cord Stimulation in Persistent Nonoperated Low Back Pain of Neuropathic Origin: Maiden Back Study

PURPOSE

Spinal cord stimulation (SCS) is a recommended treatment for chronic neuropathic pain. Persistent nonoperative low back pain of neuropathic origin has profound negative impacts on patient's lives. This prospective, open label, research study aimed to explore the use of SCS in patients with associated features of central sensitisation such as allodynia and hyperalgesia.

MATERIALS AND METHODS

Twenty-one patients with back pain and hyperalgesia or allodynia who had not had prior spinal surgery underwent a SCS trial followed by full implantation. SCS comprised administering electrical impulses epidurally at a frequency of 10 kHz and pulse width of 30 μsec. Patients attended follow-up visits after 6 and 12 months of SCS. Repeated measure ANOVAs/Friedman tests explored change after 6 and 12 months of 10 kHz SCS. Independent sample t-tests/Mann-Whitney U tests examined differences in response after 12 months of 10 kHz SCS.

RESULTS

Back and leg pain, quality of life (QoL), pain-related disability, and morphine equivalence significantly improved compared with baseline following 6 and 12 months of 10 kHz SCS. There were no increases in the consumption of opioids, amitriptyline, gabapentin or pregabalin in any patient. After 12 months of treatment, 52% encountered ≥50% improvement in back pain, 44% achieved remission (0-3 cm back pain VAS), 40% reported ODI scores between 0 and 40 and 60% experienced a reduction of at least 10 ODI points. Patients reporting ≥10-point improvement in ODI had significantly longer pain history durations and experienced significantly greater improvements in back pain, leg pain and QoL than those reporting <10-point improvement in ODI.

CONCLUSION

The 10 kHz SCS improved back and leg pain, QoL, pain-related disability and medication consumption in patients with nonoperative back pain of neuropathic origin. With further research incorporating a sham control arm, the efficacy of 10 kHz SCS in this patient cohort will become more established.

Pain relief and opioid usage in upper limb and neck pain patients after 10-kHz spinal cord stimulation treatment: subanalysis of USA studies

Aim: It is argued that chronic pain patients who reduce/eliminate their opioids may have compromised pain relief. This study therefore aimed to analyze if reduced opioid consumption associated with 10-kHz spinal cord stimulation adversely affected pain relief. Methods: Post hoc analysis was performed on data from two prospective studies in subjects with upper limbs and neck pain conducted in USA. Results & conclusion: A 10-kHz spinal cord stimulation treatment was associated with reduction in mean visual analog scale scores for upper limbs and neck pain and mean daily opioid consumption. Pain scores decreased in subjects who decreased opioid use and in those who maintained/increased use. Opioid reduction and pain relief was also achieved in subjects taking >90 mg morphine equivalents of opioids at baseline.

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.

The impact of the COVID-19 pandemic on patients awaiting spinal cord stimulation surgery in the United Kingdom: a multi-centre patient survey

Introduction

Spinal cord stimulation (SCS) is a recommended treatment for chronic refractory neuropathic pain. During the COVID-19 pandemic, elective procedures have been postponed indefinitely both to provide capacity to deal with the emergency caseload and to avoid exposure of elective patients to COVID-19. This survey aimed to explore the effect of the pandemic on chronic pain in this group and the views of patients towards undergoing SCS treatment when routine services should resume.

Methods

This was a prospective, multi-centre telephone patient survey that analysed data from 330 patients with chronic pain who were on an SCS waiting list. Questions focussed on severity of pain, effect on mental health, medication consumption and reliance on support networks during the COVID-19 pandemic. Views towards undergoing SCS therapy were also ascertained. Counts and percentages were generated, and chi-square tests of independence explored the impact of COVID-19 risk (very high, high, low) on survey responses.

Results

Pain, mental health and patient's ability to self-manage pain deteriorated in around 47%, 50% and 38% of patients, respectively. Some patients reported increases in pain medication consumption (37%) and reliance on support network (41%). Patients showed a willingness to attend for COVID-19 testing (92%), self-isolate prior to SCS (94%) and undergo the procedure as soon as possible (76%).

Conclusion

Our findings suggest that even during the COVID-19 pandemic, there remains a strong clinical need for patients with chronic pain identified as likely SCS responders to be treated quickly. The current prioritisation of new SCS at category 4 (delayed more than 3 months) is challenged judging by this national survey. These patients are awaiting SCS surgery to relieve severe intractable neuropathic pain. A priority at category 3 (delayed up to 3 months) or in some selected cases, at category 2 are the appropriate priority categories.

Improving care of chronic pain patients with spinal cord stimulator therapy amidst the opioid epidemic

The US government and other key stakeholders including professional medical bodies have amended recommendations in recent years to emphasize using no opioids or the lowest effective dose of opioids needed for treatment of chronic pain. However, there remains an unmet need for pain treatments that can both relieve the pain of patients and reduce the doses of opioids they require. The Center for Medicare and Medicaid Services (CMS) is currently considering such treatments through the SUPPORT ACT and has recently conferred with the Health and Human Services (HHS) Inter-agency Pain Management Task Force to consider such therapies. We reviewed literature evidence in PubMed on pain relief and opioid reduction following spinal cord stimulation (SCS) treatment. SCS presents an effective non-pharmacologic pain treatment modality that has been used for decades to reduce chronic pain from trauma or neuropathy and has been shown to either stabilize or reduce opioid use in some patients with painful conditions. A more recently developed high-frequency SCS modality, 10 kHz SCS, has the advantage of being paresthesia-independent. It has been shown to be associated with significant reductions in opioid consumption after stimulation therapy was initiated, and many patients even taking high doses of opioids (> 90 mg morphine equivalent dose per day) were able to reduce their opioid intake to levels associated with less risk. The evidence shows that reduction of opioids as early in the treatment process as possible is desirable to reduce patient risk and improve pain relief from stimulation therapy.

Development of an Educational Curriculum for Spinal Cord Stimulation

BACKGROUND

Spinal cord stimulators (SCSs) are used for treating chronic pain. The number of SCSs implanted each year is on the increase. The North American Neuromodulation Society (NANS) education committee aimed to develop a SCS curriculum as a tool to guide physicians at different training levels, based on the most recent evidence.

MATERIAL AND METHODS

A multidisciplinary (anesthesiology, physical medicine, neurosurgery, and neurology), taskforce representing the education committee of the NANS met to develop a SCS curriculum following the Accreditation Council for Graduate Medical Education (ACGME) milestones. The task force used the best available evidence and knowledge to develop the curriculum. Once developed, the SCS curriculum was then approved by the NANS board.

RESULTS

The task force developed a SCS training curriculum. Milestones included patient care and procedural skills, system-based practice, medical knowledge, interpersonal communication, practice based learning and professionalism. Each milestone was defined for three categories, early learner, advanced learner, and practitioner.

CONCLUSION

A multidisciplinary task force of the NANS education committee developed a SCS training curriculum that defines ACGME milestones for basic learners, advanced learners, and practitioners.

Opioids in Older Adults: Indications, Prescribing, Complications, and Alternative Therapies for Primary Care

The fact that opioids are valuable tools for the management of pain has been known and used for thousands of years. Currently, millions of Americans are treated annually with opioids, and many of these patients are elderly. Opioids present risks to geriatric patients, some of which are unique to the population, and providers should have a good grasp of those risks. An understanding of how to select appropriate medications for the management of pain and of the myriad of alternatives available for pain management is vital to the care of older patients. This article presents a review, for primary care providers, of issues unique to opioid management in older adults.

Pain medicine fellow neuromodulation surgical skill assessment tool: a pilot

OBJECTIVE

Spinal cord stimulation (SCS) is an evidence-based therapy for the treatment of refractory pain. Current American College of Graduate Medical Education requirements for pain medicine fellowship graduation include observation of five neuromodulation cases. Matriculating fellows have varying degrees of technical skill, training, and experience. The purpose of this study was to use an innovative skill-based assessment tool using the validated Zwisch scale to evaluate fellow surgical performance during SCS cases.

DESIGN

Cross-sectional survey SETTING: Mayo Clinic, Rochester, Minnesota.

SUBJECTS

Consultant faculty (10) in the Division of Pain Medicine and pain medicine fellows (5).

METHODS

A list of faculty-driven neuromodulation surgical objectives was formed and a rubric was created that focused on technical approach, imaging, epidural access and wound closure. Consultants who perform surgical cases were instructed to use the Zwisch scale as a guide to evaluate fellow surgical performance during a neuromodulation case. Faculty and fellows were surveyed before and after implementation of the tool to determine their satisfaction with use of the skill assessment tool.

RESULTS

The consultants reported they were more satisfied, consistent, and efficient with feedback provided to the trainee on every aspect of neuromodulation surgical cases. The improvement was most significant during the fellows' intraoperative skill assessment. The fellows indicated increased satisfaction, improved communication, and increased efficiency of feedback when the tool was utilized. The fellows reported greater intraoperative skill assessment and consistency of feedback provided.

CONCLUSIONS

The diverse nature of primary specialty backgrounds observed in pain medicine fellowship training offers a unique opportunity to assess and improve fellow skill and surgical competence in the field of neuromodulation. Both faculty and fellows reported improved satisfaction, consistency and efficiency with feedback provided. Importantly, this pilot project observed that implementation of a skill assessment tool was beneficial for both the faculty and fellow as the feedback received was viewed as strongly beneficial to the educational experience.

Opioid-sparing effects of 10 kHz spinal cord stimulation: a review of clinical evidence

Chronic pain is a common condition that affects the physical, emotional, and mental well‐being of patients and can significantly diminish their quality of life. Due to growing concerns about the substantial risks of long‐term opioid use, both governmental agencies and professional societies have recommended prioritizing the use of nonpharmacologic treatments, when suitable, in order to reduce or eliminate the need for opioid use. The use of 10 kHz spinal cord stimulation (10 kHz SCS) is one such nonpharmacologic alternative for the treatment of chronic, intractable pain of the trunk and limbs. This review examines published clinical data regarding the efficacy of 10 kHz SCS for decreasing chronic pain in patients and its potential to reduce or eliminate opioid usage. Multiple prospective and retrospective studies in patients with intractable pain demonstrated that 10 kHz SCS treatment provided ≥50% pain relief in >70% patients after at least 1 year of treatment. Pain relief with 10 kHz SCS therapy ranged from 54% to 87% in the studies. More importantly, the mean daily dose of opioids required by patients in these studies was reduced after 10 kHz SCS treatment, and on average over 60% patients in studies either reduced or eliminated opioids at the last follow‐up.

Does Spinal Cord Stimulation Due to Failed Back Surgery Syndrome Lead to Permanent Occupational Disability?

OBJECTIVE

Spinal cord stimulation (SCS) is a recommended treatment method for patients afflicted by failed back surgery syndrome (FBSS). Although SCS is shown to be clinically effective, not many patients return to work (RTW). The aim of this study is to assess the RTW rate of these patients.

MATERIALS AND METHODS

We prospectively evaluated 102 patients with FBSS, managed by low frequency SCS at a single institution in Poland. RTW rate was the main endpoint in the study. Additionally, we browsed the first 300 records in Google and extracted the suggested RTW time post-SCS implantation.

RESULTS

Mean follow-up was 8.5 years. 79.4% of patients were actively working at the baseline. Fifteen patients were sick leave benefit claimants (15/81; 18.5%) and six were permanently disabled (6/81; 7.4%). In the follow-up, 40 did not change their work status. Only 2 of 21 patients resumed work and the total RTW rate was 9.5%. On the other hand, 38 of 81 patients (46.9%), who actively worked before SCS, gained disability status. Out of entire group, 20.6% (21 of 102) were not working at the baseline and 55.9% (57 of 102) were not working in the follow-up. Neither factor influenced RTW rate. In the second stage of the study, internet data search yielded a mean RTW time of 6.1 weeks.

CONCLUSIONS

Unlike the well-analyzed effectiveness of SCS, RTW remains an underutilized outcome measure. The RTW rate in our series was the second lowest in the reviewed literature. We demonstrated that half of the patients with an implanted SCS either did not resume their work or left their job.

The effect of spinal cord stimulation on pain medication reduction in intractable spine and limb pain: a systematic review of randomized controlled trials and meta-analysis

Objective: To synthesize the evidence regarding the effect of spinal cord stimulation (SCS) on opioid and pain medication reduction in patients with intractable spine or limb pain.

Methods: A comprehensive literature search was conducted to identify RCTs of patients with chronic back and/or limb pain of greater than one year duration. Only comparative studies were included (ie, conventional SCS vs medical therapy, conventional SCS vs high-frequency SCS) and were required to have a minimum follow-up period of 3 months. Random effect meta-an alysis was used to compare the three interventions. Results were expressed as odds ratio (OR) or weighted mean difference (WMD) with 95% confidence intervals (CI).

Results: We identified five trials enrolling 489 patients. Three of the trials reported the results as a number of patients who were able to reduce or eliminate opioid consumption in the SCS vs medical therapy group. The odds of reducing opioid consumption were significantly increased in the SCS group compared to medical therapy (OR 8.60, CI {1.93–38.30}). Two of the trials reported the results as mean medication dose reduction as measured by the Medication Quantification Scale (MQS) in the SCS group vs medical therapy group. MQS score significantly decreased in the SCS group and not in the medical group (WMD –1.97, 95% CI {–3.67, –0.27}). One trial reported a number of patients in high-frequency SCS who were able to reduce opioids vs number of patients in conventional SCS group who were able to reduce opioids. Thirty-four percent of the patients in the high-frequency group and 26% of the patients in the conventional SCS group were able to reduce opioid consumption; however, there was not a significant difference between groups (OR 1.43, 95% CI {0.74, 2.78}). This trial also quantified the opioid reduction in morphine equivalent dosage (MED). In the high-frequency SCS group, average MED decreased by 24.8 mg vs average MED decrease of 7.3 mg in the conventional SCS group. Again, the difference between groups did not reach statistical significance (–17.50, CI {–66.27, 31.27}).

Conclusions: In patients with intractable spine/limb pain, SCS was associated with increased odds of reducing pain medication consumption. However, results should be treated with caution as available data were limited, and clinical significance of these findings requires further study.

Spinal Cord Stimulation

Spinal cord stimulation (SCS) has been well established as a safe and effective treatment of pain derived from a wide variety of etiologies. Careful patient selection including a rigorous trial period and psychological evaluation are essential. When patients proceed to permanent implantation, various considerations should be made, such as the type of lead, type of anesthesia, and waveform patterns for SCS. This article discusses the common indications for SCS, patient selection criteria, and pertinent outcomes from randomized clinical trials related to common indications treated with SCS. Technical considerations, such as type of implant, anesthesia, and programming, are also discussed.