Spinal cord stimulation in pain management: a review

Pain-relieving Effects of Autologous Fat Grafting in Breast Cancer Surgery: A Scoping Review

Background

Chronic pain is relatively common after breast cancer surgery, including breast reconstruction. Autologous fat grafting (AFG) has gained attention as a novel method for breast reconstruction, and recent clinical studies have also shown effects of AFG on alleviation of chronic pain after breast cancer surgery. Our objective was to conduct a scoping review of studies that have examined these effects with clearly defined clinical outcomes.

Methods

A literature search was conducted using three databases: PubMed, MEDLINE, and Google Scholar, following PRISMA guidelines and the Arkesy and O'Malley framework. The search focused on clinical studies of the effects of AFG on chronic pain after breast cancer surgery. All studies reporting functional outcomes, return to work, and secondary surgery in a repeat operation were identified.

Results

Of the 148 studies identified in the search, 11 studies with a total of 684 patients were included in the review. The average volume of fat grafted was approximately 128 mL over an average of 1.6 sessions. The most common time point for assessment was 1 year post-AFG. In all studies with an evidence level of 3 or lower, AFG showed positive results in alleviating pain after breast cancer surgery. However, one of the three randomized controlled trials did not show clinically significant effects.

Conclusions

Most of the studies examined in this review suggested pain-relieving effects of AFG. However, there was one randomized controlled trial in which these effects were not confirmed, indicating a need for further accumulation of cases and performance of new, well-designed randomized controlled trials.

Neuromodulation and Habituation: A Literature Review and Conceptional Analysis of Sustaining Therapeutic Efficacy and Mitigating Habituation

Spinal cord stimulation (SCS) is a therapeutic modality for the treatment of various chronic pain conditions that has rapidly evolved over the past 50 years. Unfortunately, over time, patients implanted with SCS undergo a habituation phenomenon leading to decreased pain relief. Consequently, the discovery of new stimulation waveforms and SCS applications has been shown to prolong efficacy and reduce explantation rates. This article explores various SCS waveforms, their applications, and proposes a graded approach to habituation mitigation. We suspect the neural habituation phenomenon parallels that seen in pharmacology. Consequently, we urge further exploration of the early introduction of these stimulation strategies to abate spinal cord stimulation habituation.

Treatment Disparities in Hispanic Patients with Chronic Pain: An Evidence-Based Narrative Review

PURPOSE OF REVIEW

The purpose of this narrative review is to summarize healthcare disparities experienced by Hispanic and Latino/Latinx patients with chronic pain, evaluate the existing literature exploring the specific therapeutic inequities affecting this patient population, and identify gaps in the literature requiring future study.

RECENT FINDINGS

Hispanic and Latino/Latinx patients experience disparities in chronic pain management. They are less likely to be prescribed pharmacologic therapies, including non-steroidal anti-inflammatory drugs and opioids. Hispanic and Latino/Latinx patients are also less likely to receive spinal cord stimulators and may be charged higher costs for them. There are no published studies specifically assessing Hispanic and Latino/Latinx patients' utilization and outcomes from other common interventional pain procedures (e.g., epidural steroid injections, radiofrequency ablation). Limited data suggest non-pharmacologic treatments, such as cognitive behavioral therapy and complementary/integrative health modalities, might have more benefit for this population, potentially because of greater utilization. Hispanic and Latino/Latinx patients experience disparities in chronic pain management. There is a paucity of data available pertaining specifically to pain-related outcomes and the utilization of pain treatment modalities, especially in regard to interventional procedures. Additional research is urgently needed in order to understand the full extent of these disparities and develop solutions to provide more equitable care.

Correlation between spinal cord stimulation analgesia and cortical dynamics in pain management

AIM

Spinal cord stimulation (SCS) is an effective method to treat neuropathic pain. It is necessary to identify the responders of SCS analgesia before implantation. The aim of this study is to investigate the relationship between the cortical dynamics and SCS analgesia responders in pain management.

METHODS

Resting-state EEG recording was performed in patients who underwent short-term implantation of spinal cord stimulation for pain therapy. We then did spectral analysis to capture the pattern of cortical oscillation between neuromodulation therapy analgesia responders and nonresponders.

RESULTS

About 58.3% (14 out of 24) of participants were considered as analgesia responders, with average visual analogue scores reduction of 4.8 ± 1.0 after surgery, and 2.1 ± 0.7 for the nonresponder subgroup, respectively. The alpha oscillation was significantly enhanced in responder cohort compared with nonresponders. We also observed an increasing spectral power of gamma band in responders. Furthermore, the attenuation of pain severity was significantly correlated with the global alpha oscillation activity (r = 0.60, P = 0.002). Likely, positive and significant correlation was found between the pain relief and gamma activity (r = 0.58, P = 0.003).

CONCLUSIONS

Distinct pattern of neural oscillation is associated with the analgesic effect of spinal cord stimulation in pain management, enhancement of cortical alpha and gamma oscillation may be a predictor of analgesia responders.

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

Study design

Retrospective cohort study.

Introduction

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

Methods

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

Result

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

Conclusion

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

Immunomodulatory and endocrine effects of deep brain stimulation and spinal cord stimulation - A systematic review

INTRODUCTION

Deep Brain Stimulation (DBS) and Spinal Cord Stimulation (SCS) represent burgeoning treatments for diverse neurological disorders. This systematic review aims to consolidate findings on the immunological and endocrine effects of DBS and SCS, shedding light on the intricate mechanisms of neuromodulation.

MATERIALS AND METHODS

This systematic review, aligned with PRISMA protocols, synthesizes findings from 33 references-20 on DBS and 13 on SCS-to unravel the immunological and endocrine impacts of neuromodulation.

RESULTS

DBS interventions exhibited divergent effects on cytokines, with an increase in hepcidin levels and a variable impact on the IL-6/IL-10 ratio. While some studies reported elevated IL-6, animal studies consistently demonstrated a reduction in IL-1β and IL-6, with no significant changes in TNF-α and an increase in IL-10. Noteworthy hormonal changes included decreased corticosterone and ACTH concentrations and increased oxytocin levels following DBS of the hypothalamus. SCS mirrored similar effects on interleukins, indicating a reduction in IL-6 and IL-1β and an increase in IL-10 levels. Additionally, SCS led to reduced VEGF levels and elevated expression of neurotrophic factors such as BDNF and GDNF, particularly under burst stimulation.

CONCLUSIONS

Both DBS and SCS exert anti-inflammatory effects, manifesting as a decrease in pro-inflammatory cytokines alongside the stimulation of anti-inflammatory cytokine synthesis. These findings, observed in both animal and human models, imply that neurostimulation may modify the trajectory of neurological diseases by modulating local immune responses in an immunomodulatory and endocrine manner. This comprehensive exploration sets the stage for future research endeavors in this evolving domain.

The complex regional pain syndrome: Diagnosis and management strategies

Complex regional pain syndrome (CRPS) is a chronic disease that affects a limb following an injury or trauma. The CRPS associated with symptoms, including severe pain, swelling, as well as changes in skin color and temperature. Treatment of CRPS requires a multidisciplinary approach, with a focus on personalized treatment plans and addressing psychological factors. This review provides an overview of updates in the diagnosis and treatment of CRPS. There are clinical criteria for diagnosing CRPS, including persistent pain and swelling. The CRPS can also be diagnosed with imaging and laboratory tests. Novel insights into treatment approaches for CRPS have been gained from advances in understanding its pathophysiology. Treatment of CRPS includes both pharmacological and non-pharmacological interventions. The latest guidelines for CRPS treatment emphasize the importance of early diagnosis and intervention, personalized treatment plans, and addressing psychological factors in managing CRPS.

Neuromodulation for Adjunctive Treatment in Postmastectomy Pain Syndrome

Postmastectomy pain syndrome (PMPS) affects nearly half of patients who undergo mastectomy to treat breast cancer. As the survival rate of breast cancer increases with advancements in treatment, the incidence of PMPS is also increasing. Patients with PMPS can experience unrelenting, chronic pain refractory to traditional management with oral pharmacotherapy in conjunction with nonpharmacologic treatment (physical therapy, transcutaneous electrical nerve stimulation (TENS)). Neuromodulation is an emerging treatment modality for numerous chronic pain conditions. This case report highlights the tremendous success of spinal cord stimulator placement for a patient with PMPS.

Therapeutic Strategies for Postherpetic Neuralgia: Mechanisms, Treatments, and Perspectives

PURPOSE OF REVIEW

Postherpetic neuralgia is an annoying pain that mainly affects older people. In order to give patients more options, this review summarizes the pharmacological and interventional treatments for postherpetic neuralgia and updates the research on the efficacy, thereby providing doctors with more treatment options. The adverse effects and effective doses of its various treatments are also presented so that the therapy can be prescribed according to their concrete physical conditions. In a word, this review is dedicated to providing a comprehensive overview of the treatment options for postherpetic neuralgia and offering patients more choices.

RECENT FINDINGS

Combinational therapy is more excellent than monotherapy. The local anesthesia and gabapentin comprised outstanding compatibility. In addition, two therapeutic tools for PHN patients, especially for the intractable ones, electroacupuncture (EA), and osteopathic manipulative treatment (OMT), show their efficacy and become potential options to alleviate pain. In terms of treatment, guidelines recommend patients use tricyclic antidepressants (TCAs), gabapentin, pregabalin, and 5% lidocaine patches as the first-line medications, and gabapentin is investigated most, especially the gabapentin enacarbil (GEn). And drug efficacy can be limited by adverse effects and tolerated doses. Interventional treatments, with their invasiveness and operational difficulty, are usually considered for intractable patients. Combinational therapies may be used when a single therapy cannot achieve the desired effect. Therapies such as OMT and EA have also been proposed to palliate pain in some cases, and future directions of treatment may be investigated in Chinese medicine and acupuncture.

Machine Learning in Spinal Cord Stimulation for Chronic Pain

Spinal cord stimulation (SCS) is an effective treatment for chronic neuropathic pain. The success of SCS is dependent on candidate selection, response to trialing, and programming optimization. Owing to the subjective nature of these variables, machine learning (ML) offers a powerful tool to augment these processes. Here we explore what work has been done using data analytics and applications of ML in SCS. In addition, we discuss aspects of SCS which have narrowly been influenced by ML and propose the need for further exploration. ML has demonstrated a potential to complement SCS to an extent ranging from assistance with candidate selection to replacing invasive and costly aspects of the surgery. The clinical application of ML in SCS shows promise for improving patient outcomes, reducing costs of treatment, limiting invasiveness, and resulting in a better quality of life for the patient.

Spinal cord stimulation for refractory pericarditis: a case report and a review of the mechanism of action

Background and objectives

In recent years, spinal cord stimulation (SCS) has emerged as a promising management option for chronic pain of multiple etiologies. While its effectiveness has been strongly suggested in many patients, the exact mechanism of action of SCS is incompletely understood. This article reviews the leading mechanisms underlying the analgesic and cardiovascular effects of SCS and reports its novel benefits in a case of recurrent pericarditis.

Literature review

Throughout history, the analgesic properties of SCS were thought to arise via stimulation of the spinothalamic tract. Although this mechanism has been thoroughly reported, new research and patient outcomes from SCS have revealed various additional properties that cannot be fully explained by this mechanism alone. Evidence suggests that SCS enhances calcitonin gene-related peptide release and modulates inflammatory cytokine secretion, sympathetic tone, and inhibitory neurotransmitter secretion. These distinct mechanisms likely collectively contribute to the therapeutic effects of SCS on the cardiovascular system and pain management.

Case report

We report the case of a 48-year-old male patient with recurrent pericarditis, characterized by refractory angina-like pain and reduced left ventricular ejection fraction (LVEF). After 1 year of having a spinal cord stimulator implanted, the patient is free from pain and narcotics, with a reduction of 428 mg equivalent dose of morphine. The patient's LVEF increased from 40% to 45% without changes to his previous medical treatment. This is the first reported case of refractory pericarditis managed with spinal cord stimulation.

Conclusion

Recognizing the improved pain management, reduced narcotic usage, and improved LVEF in our patient following SCS is critical to paving the way toward a complete understanding of the mechanism of action of SCS. This case reveals the therapeutic potential of SCS for cardiovascular pathologies other than refractory angina pectoris.

Spinal cord stimulator implantation with immediate post-operative paraplegia: Case report

The most common complication of dorsal column spinal cord stimulator implantation is hardware migration. Spinal cord injury following paddle or percutaneous lead implant is rarely reported, with an overall incidence of 0.42%. This report describes a case of immediate post-operative incomplete paraplegia following implantation of one thoracic paddle electrode to address post-laminectomy pain syndrome. Despite emergent removal of the electrode, post-operative corticosteroids, and a course of inpatient rehabilitation, the patient discharged with persistent incomplete paraplegia. Although there is rare occurrence of spinal cord injury with spinal cord neuromodulation, it is important to recognize risk factors which may lead to similar devastating complications.

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

OBJECTIVE

The objective of this meta-analysis was to approximate the incidence of overall lead migration, clinically significant lead migration, and asymptomatic lead migration in patients who have undergone spinal cord stimulator implantation.

MATERIALS AND METHODS

A comprehensive literature search was performed for studies published before May 31, 2022. Only randomized controlled trials and prospective observational studies with more than ten patients were included. Two reviewers analyzed the articles from the literature search for final inclusion, after which, study characteristics and outcome data were extracted. The primary dichotomous categorical outcome variables were the incidence of overall lead migration, clinically significant lead migration (defined as lead migration resulting in loss of efficacy), and asymptomatic lead migration (defined as lead migration discovered incidentally on follow-up imaging) in patients with spinal cord stimulator implant. Freeman-Tukey arcsine square root transformation for meta-analysis of proportions using random effects (DerSimonian and Laird method) was used to calculate incidence rates for the outcome variables. Pooled incidence rates and 95% CIs were calculated for the outcome variables.

RESULTS

Fifty-three studies met the inclusion criteria, with a total of 2932 patients having received spinal cord stimulator implants. The pooled incidence of overall lead migration was 9.97% (95% CI of 7.62%-12.59%). Only 24 of the included studies commented on the clinical significance of reported lead migrations, of which every lead migration was clinically significant. In these 24 studies, 96% of the reported lead migrations required a revision procedure or explant. Unfortunately, no studies that reported lead migration commented on asymptomatic lead migrations; therefore, the incidence of asymptomatic lead migrations could not be defined.

CONCLUSIONS

This meta-analysis found that the rate of lead migration in patients who have received spinal cord stimulator implants is approximately one in ten patients. This likely closely approximates the incidence of clinically significant lead migration owing to the included studies not routinely performing follow-up imaging. Therefore, lead migrations were primarily discovered owing to loss of efficacy, and no included studies clearly reported asymptomatic lead migration. The results of this meta-analysis can be used to inform patients more accurately on the risks and benefits of spinal cord stimulator implantation.

Paddle-Lead Spinal-Cord Stimulation Surgeries for Chronic Neuropathic Pain: A Single Surgeon Case-Series Outcome Analysis in Indian Population

Background Spinal-cord stimulation (SCS) for relief of chronic neuropathic pain is well established.

Objective The inherent limitations with conventional percutaneous lead SCS are lead migration, positional variations in stimulation, as well as possible nonreplication of benefits after permanent SCS implantation, which were experienced during a positive trial period. To circumvent these limitations, we analyzed five consecutive cases of chronic intractable neuropathic pain who underwent direct SCS paddle lead placement during the trial period for pain relief. In addition, during the process of placing a permanent paddle lead, the impediment created by prior epidural scarring in such chronic patients can be obviated mechanically thereby increasing the efficacy of the procedure.

Material and Methods The demographic details, diagnosis, preoperative visual analogue scale score (VAS), and follow-up VAS were recorded. Surgical procedure consisted of a standard dorsal laminotomy followed by placement of permanent paddle leads.

Results All patients reported significant improvement in their VAS scores. Mean duration of follow-up was 23.6 months (9–35 months). Mean preoperative VAS was 9.4 and 1.4 at the last follow-up. No major complications were found.

Conclusion With careful patient selection and appropriate surgical strategy, it was possible to implant permanent paddle leads during SCS trial itself in our five patients thereby replicating and sustaining the trial period pain relief. We argue that this can be a new cost-effective and reliable technique for the placement of SCS leads achieving excellent and sustained pain relief.

Erector Spinae Plane Catheter for Postoperative Thoracotomy Pain in a Patient With Indwelling Spinal Cord Stimulators: A Case Report

Analgesia after thoracotomy is challenging but important as inadequate pain control may result in early postoperative complications and a higher risk for post-thoracotomy pain syndrome. The authors report the successful utilization of an erector spinae plane (ESP) catheter for post-thoracotomy analgesia in a 40-year-old female with two dual-leaded spinal cord stimulators (SCS) in the cervical and thoracic levels. Although thoracic epidural analgesia is the current standard, epidural catheterization may present with obstructive, mechanical, or infectious concerns in patients with SCS. The ESP block may be a preferable approach to postoperative analgesia after thoraco-abdominal surgery over the thoracic epidural for patients with SCS.

Successful utilization of high frequency spinal cord stimulation for HIV and chemotherapy induced polyneuropathy

We present a case of a 53-year-old male who presented with functionally limiting bilateral lower extremity neuropathic pain secondary to multiple subtypes of small fiber neuropathy. He had failed management with multiple conservative measures including oral medications, physical therapy and desensitization techniques. He ultimately underwent placement of a spinal cord stimulator and continued to experience 80% improvement of his pain, as well as improved function and quality of life at 5 month follow-up. To our knowledge, this is the first reported case of successful treatment of multiple subtypes of small fiber neuropathy with spinal cord stimulator.

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

OBJECTIVE

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

MATERIALS AND METHODS

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

RESULTS

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

CONCLUSIONS

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

Materials for Implantable Surface Electrode Arrays: Current Status and Future Directions

Surface electrode arrays are mainly fabricated from rigid or elastic materials, and precisely manipulated ductile metal films, which offer limited stretchability. However, the living tissues to which they are applied are nonlinear viscoelastic materials, which can undergo significant mechanical deformation in dynamic biological environments. Further, the same arrays and compositions are often repurposed for vastly different tissues rather than optimizing the materials and mechanical properties of the implant for the target application. By first characterizing the desired biological environment, and then designing a technology for a particular organ, surface electrode arrays may be more conformable, and offer better interfaces to tissues while causing less damage. Here, the various materials used in each component of a surface electrode array are first reviewed, and then electrically active implants in three specific biological systems, the nervous system, the muscular system, and skin, are described. Finally, the fabrication of next-generation surface arrays that overcome current limitations is discussed.

Effect of electrical stimulation on patients with diabetes-related ulcers: a systematic review and meta-analysis

BACKGROUND

This study aimed to systematically review the literature to better understand the efficacy of electrical stimulation (ES) for the treatment of patients with diabetes-related ulcers.

METHODS

We searched the Embase, Medline, and Cochrane Library databases through July 31, 2021. Original trials for ES treatment of patients with diabetes-related ulcers with placebo or standard care as the control group were included. The primary outcomes were ulcer area reduction and healing rates. Meta-analyses were performed to compare the standardized mean difference (SMD) in the percentage of ulcer reduction and risk ratio of non-healing rates between ES treatment and placebo or standard care. We used the Revised Cochrane risk-of-bias tool for randomized trials to assess the risk of bias for each included article. Funnel plots and Egger's test were used to assess publication bias.

RESULTS

Compared to placebo or standard care, ES had a significant benefit for the treatment of patients with diabetes-related ulcers in terms of percentage of ulcer reduction (SMD = 2.56, 95% CI: 1.43-3.69; P < 0.001 (Q-test), I² = 93.9%) and ulcer healing rates [risk ratio of non-healing rates for the ES group was 0.72 (95% CI: 0.54-0.96; P = 0.38 (Q-test), I² = 2.3%)]. Two, four, and three of the included studies were categorized into low risk of bias, some concerns, and high risk of bias, respectively. No publication bias was found.

CONCLUSIONS

Based on the findings of this meta-analysis, ES could be used to treat patients with diabetes-related ulcers. ES treatment was effective for ulcer area reduction and ulcer healing, although it had a high heterogeneity level among the included studies. Pulsed current ES has the potential benefit of increasing ulcer healing compared to direct current ES. Further large-scale clinical trials are needed to define the adverse events and potentiators of ES in the treatment of patients with diabetes-related ulcers.

Adverse Events Associated With 10-kHz Dorsal Column Spinal Cord Stimulation: A 5-Year Analysis of the Manufacturer and User Facility Device Experience (MAUDE) Database

BACKGROUND

High-frequency (10-kHz) spinal cord stimulation (SCS) continues to be an emerging therapy in chronic pain management. The same complications that plagued earlier SCS systems may affect newer stimulation technologies, although there is limited data on the type of complications and surgical management of these complications.

OBJECTIVE

The aim of this study was to systematically examine real-world complications associated with 10-kHz SCS reported on the Manufacturer and User Facility Device Experience (MAUDE) database.

MATERIALS AND METHODS

The MAUDE database was queried for entries reported between January 1, 2016 and December 31, 2020. Entries were classified into procedural complications, device-related complications, patient complaints, surgically managed complications, serious adverse events, and/or other complications. Primary outcomes included type and frequency of complications, and surgical management of complications.

RESULTS

A total of 1651 entries were analyzed. Most entries were categorized as procedural complications (72.6%), followed by serious adverse events (10.5%), device-related complications (10.5%), and patient complaints (9.9%). Most complications were managed surgically with explant (50.9%) rather than revision (5.0%) or incision/drainage (6.6%). Of procedural complications, the most common entries included non-neuraxial infection (52.9%), new neurological symptoms (14.7%), and dural puncture (9.5%). Of device-related complications, the most common entries included lead damage (41.6%), erosion (18.5%), and difficult insertion (11.5%).

CONCLUSION

This retrospective 5-year analysis of complications from10-kHz SCS provides a real-world assessment of safety data unique for this stimulation modality. This analysis may help inform future clinical decisions, lead to device enhancement and optimization, and improve mitigation of risks to provide safe and efficacious use of 10-kHz SCS.

Imaging Biomarker Development for Lower Back Pain Using Machine Learning: How Image Analysis Can Help Back Pain

State-of-the-art diagnosis of radiculopathy relies on "highly subjective" radiologist interpretation of magnetic resonance imaging of the lower back. Currently, the treatment of lumbar radiculopathy and associated lower back pain lacks coherence due to an absence of reliable, objective diagnostic biomarkers. Using emerging machine learning techniques, the subjectivity of interpretation may be replaced by the objectivity of automated analysis. However, training computer vision methods requires a curated database of imaging data containing anatomical delineations vetted by a team of human experts. In this chapter, we outline our efforts to develop such a database of curated imaging data alongside the required delineations. We detail the processes involved in data acquisition and subsequent annotation. Then we explain how the resulting database can be utilized to develop a machine learning-based objective imaging biomarker. Finally, we present an explanation of how we validate our machine learning-based anatomy delineation algorithms. Ultimately, we hope to allow validated machine learning models to be used to generate objective biomarkers from imaging data-for clinical use to diagnose lumbar radiculopathy and guide associated treatment plans.

Real-World Cost-Effectiveness Analysis of Spinal Cord Stimulation vs Conventional Therapy in the Management of Failed Back Surgery Syndrome

Purpose

Failed back surgery syndrome (FBSS) causes disability and lowers health-related quality of life (HRQoL) for patients. Many patients become refractory to conventional medical management (CMM) and spinal cord stimulation (SCS) is advised. However, comparative cost-effectiveness research of both clinical approaches still lacks further evidence. This probabilistic cost-effectiveness analysis compares CMM versus SCS plus CMM in FBSS patients for a 5-year period in Spain.

Patients and Methods

Patient-level data was obtained from a 2-year real-world study (SEFUDOCE) of adults diagnosed with FBSS who were treated with CMM or SCS. Incremental cost-effectiveness ratios (ICER) were estimated in terms of direct clinical cost and quality-adjusted life years (QALYs). Costs (€ for 2019) were estimated from the Spanish National Health Service (NHS) perspective. We applied a yearly discount rate of 3% to both costs and outcomes and performed a probabilistic sensitivity analysis using bootstrapping.

Results

After 2 years, the health-related quality of life measured by the EQ-5D displayed greater improvements for SCS patients (00.39) than for improved CMM patients (0.01). The proportion of SCS patients using medication fell substantially, particularly for opioids (-49%). In the statistical model projection, compared with the CMM group at year 5, the SCS group showed an incremental cost of € 15,406 for an incremental gain of 0.56 0.56 QALYs, for an ICER of € 27,330, below the €30,000 willingness-to-pay threshold for Spain. SCS had a 79% of probability of being cost-effective.

Conclusion

SCS is a cost-effective treatment for FBSS compared to CMM alone based on real-world evidence.

Skin Closure Technique and Postprocedural Pain after Spinal Cord Stimulator Implantation: A Retrospective Review

Spinal cord and dorsal root ganglion stimulation are minimally invasive surgical techniques used to treat an array of chronic pain disorders. There is a paucity of data related to defining best practices in these specific patient populations, and historically, providers have relied on consensus committees to opine on the best techniques for patient safety and experience. The most efficacious mechanism of surgical closure—specifically a running suture closure compared to a surgical staple closure—is debated. A retrospective review of 155 patients implanted with either a spinal cord or dorsal root ganglion stimulator between 2017 and 2019 was undertaken to determine if the type of surgical closure was related to degree of postoperative surgical site discomfort. The primary outcome showed no statistically significant difference on postoperative pain scores between the suture (6.0 (IQR 5.0–8.0)) and staple (7.0 (IQR 5.0–8.0)) cohorts at postoperative day (POD) #1 (adjusted β 0.17 (95% CI −0.61 to 0.95), P=0.670). This finding held for postoperative pain scores at POD #10 as well (staples (1.0 (IQR 0.0–4.0)) and suture (2.0 (IQR 0.0–5.0), adjusted β −0.39 (95% CI −1.35 to 0.58), P=0.432)). A regression analysis was performed to identify secondary factors impacting postoperative pain scores. Higher preoperative pain score (β 0.50 (95% CI 0.09 to 0.92), P=0.019) and female gender (β 1.09 (95% CI 0.15 to 2.02), P=0.023) were predictive of higher incisional pain scores at POD#10. Increasing age was associated with decreased incisional pain scores at POD#10 (β −0.06 (95% CI −0.09 to −0.03), P < 0.001). These findings are of interest to the pain practitioner and may be valuable in preoperative discussions with prospective patients.

Pulsed Radiofrequency of the Trigeminal Ganglion for Treating Postherpetic Neuralgia of the Ophthalmic Branch

Postherpetic neuralgia (PHN) is a painful, long-lasting condition as a consequence of nerve damage resulting from a herpes zoster infection. Although there are many different treatments available to reduce pain duration and severity, PHN is often refractory to them and no single therapy shows an effective cure for all cases of PHN, especially for those involving the ophthalmic branch of the trigeminal nerve. Pulsed radiofrequency (PRF) is a minimally invasive procedure for pain treatment that has been practiced over the past decade. However, its clinical efficacy and safety for treating PHN involving the ophthalmic branch of the trigeminal nerve have not been evaluated. Objective. This study aimed to evaluate the efficacy and safety of PRF for treating PHN involving the ophthalmic branch of the trigeminal ganglion. Study Design. An observational study. Setting. All patients received PRF of the ophthalmic branch of the trigeminal nerve, pain intensity was assessed by a visual analogue scale (VAS), and complications before and after PRF stimulation were noted. Methods. Thirty-two patients with PHN of the ophthalmic branch were treated by PRF of the ophthalmic branch with controlled temperature at 42°C for 8 min. Pain relief, corneal reflex, sleep quality, and satisfaction were assessed for all patients. Results. Thirty out of 32 patients (93.75%) reported significant pain reduction after PRF treatment. Twenty-eight of them (87.5%) were satisfied with their sleep and obtained a pain score lower than 3 following the procedure. Only two patients had a recurrence of the severe burning pain and returned to the hospital for other medical therapies 2 weeks after the PRF procedure. No patient lost the corneal reflex. Limitations. This study is an observational study and a nonprospective trial with a short-term follow-up period. Conclusion. PRF of the trigeminal ganglion of the ophthalmic branch can significantly reduce pain sensation and improve sleep quality and satisfaction for PHN of the ophthalmic branch.

Successful application of burst spinal cord stimulation for refractory upper limb pain: a case series

Spinal cord stimulation (SCS) has been used to treat sustained pain that is intractable despite various types of treatment. However, conventional tonic waveform SCS has not shown promising outcomes for spinal cord injury (SCI) or postamputation pain. The pain signal mechanisms of burst waveforms are different to those of conventional tonic waveforms, but few reports have presented the therapeutic potential of burst waveforms for the abovementioned indications. This current case report describes two patients with refractory upper limb pain after SCI and upper limb amputation that were treated with burst waveform SCS. While the patients could not obtain sufficient therapeutic effect with conventional tonic waveforms, the burst waveforms provided better pain reduction with less discomfort. However, further studies are necessary to better clarify the mechanisms and efficacy of burst waveform SCS in patients with intractable pain.

Bioengineering Clinically Relevant Cardiomyocytes and Cardiac Tissues from Pluripotent Stem Cells

The regenerative capacity of cardiomyocytes is insufficient to functionally recover damaged tissue, and as such, ischaemic heart disease forms the largest proportion of cardiovascular associated deaths. Human-induced pluripotent stem cells (hiPSCs) have enormous potential for developing patient specific cardiomyocytes for modelling heart disease, patient-based cardiac toxicity testing and potentially replacement therapy. However, traditional protocols for hiPSC-derived cardiomyocytes yield mixed populations of atrial, ventricular and nodal-like cells with immature cardiac properties. New insights gleaned from embryonic heart development have progressed the precise production of subtype-specific hiPSC-derived cardiomyocytes; however, their physiological immaturity severely limits their utility as model systems and their use for drug screening and cell therapy. The long-entrenched challenges in this field are being addressed by innovative bioengingeering technologies that incorporate biophysical, biochemical and more recently biomimetic electrical cues, with the latter having the potential to be used to both direct hiPSC differentiation and augment maturation and the function of derived cardiomyocytes and cardiac tissues by mimicking endogenous electric fields.

A novel method to simultaneously record spinal cord electrophysiology and electroencephalography signals

The brain and the spinal cord together make up the central nervous system (CNS). The functions of the human brain have been the focus of neuroscience research for a long time. However, the spinal cord is largely ignored, and the functional interaction of these two parts of the CNS is only partly understood. This study developed a novel method to simultaneously record spinal cord electrophysiology (SCE) and electroencephalography (EEG) signals and validated its performance using a classical resting-state study design with two experimental conditions: eyes-closed (EC) and eyes-open (EO). We recruited nine postherpetic neuralgia patients implanted with a spinal cord stimulator, which was modified to record SCE signals simultaneously with EEG signals. For both EEG and SCE, similar differences were found in delta- and alpha-band oscillations between the EC and EO conditions, and the spectral power of these frequency bands was able to predict EC/EO behaviors. Moreover, causal connectivity analysis suggested a top-down regulation in delta-band oscillations from the brain to the spinal cord. Altogether, this study demonstrates the validity of simultaneous SCE-EEG recording and shows that the novel method is a valuable tool to investigate the brain-spinal interaction. With this method, we can better unite knowledge about the brain and the spinal cord for a deeper understanding of the functions of the whole CNS.

All-in-One Spinal Cord Stimulation in Lymphoproliferative Diseases

Even patients with lymphoproliferative diseases may develop a persistent chronic pain not responsive to usual treatments due to changes in antibody production and to some treatments like radiotherapy, chemotherapy, and the administration of monoclonal antibodies, which further impair the immune defense and induce chronic inflammatory phenomena acting as a substrate for a persistent chronic pain. Five patients with indolent lymphoproliferative diseases were treated for severe pain nonresponsive to other pain reliever treatments with SCS applied with an All-in-One Shot (OS) procedure. For all patients, the estimated survival time was of 5 years or more. All patients showed a significant reduction of the intensity of pain: the mean Numerical Rating Scale was 7.4 before treatment and 2.2 after. No patient developed adverse events. Supported by the data of this study, we believe that the habit to deprive patients with an indolent form of lymphoproliferative diseases of the possibility to reduce the intensity of chronic pain by SCS treatment is extremely reductive and frustrating.

YouTube as a Source of Medical Information About Spinal Cord Stimulation

BACKGROUND

Social media platforms may play an important role in the dissemination of medical information on interventional pain procedures. This cross-sectional study quantitatively assessed the reliability and quality of information from YouTube regarding spinal cord stimulation.

MATERIALS AND METHODS

YouTube was queried on May 20, 2020 using keywords "spinal cord stimulator," "spinal cord stimulation experience," and "spinal cord stimulation risks." The top 50 viewed videos from each search were analyzed. The primary outcome was video quality, which was analyzed using the modified DISCERN (mDISCERN) criteria.

RESULTS

Seventy-nine of 103 (77%) videos were classified as useful. Fifteen of 103 (14%) videos were classified as misleading and contained nonfactual information on spinal cord stimulation. Hospitals, group practices, or physicians produced a greater proportion of useful videos compared to misleading videos (63.3% vs. 26.7%, p = 0.008). Nonmedical independent users produced a greater proportion of misleading videos compared to useful videos (73.3% vs. 16.4%, p < 0.001). Useful videos had significantly higher mDISCERN scores compared to misleading videos (2.6 vs. 1.9, p = 0.009). Nonmedical independent users produced a greater proportion of low-quality videos (mDISCERN score < 3) than high-quality videos (mDISCERN score ≥ 3; 50.8% vs. 2.4%, respectively, p < 0.001). Educational videos from professional pain medicine societies were not captured.

CONCLUSION

YouTube is an accessible platform for medical information on spinal cord stimulation, yet a significant amount of nonfactual information is present. As social media platforms continue to gain prominence in health care, future efforts to appraise the quality of medical content delivered to the public are warranted. In addition, reputable sources including professional pain medicine societies should consider collaborating with producers to disseminate high-quality video content that reaches a wider audience.

Obesity Trends Amongst Hospitalized Patients with Spinal Cord Stimulator Implants

INTRODUCTION

Chronic pain remains an important public health problem as it continues to increase healthcare-related cost. Comorbidities like obesity have been associated with efficacy of spinal cord stimulator (SCS) therapy and worse outcomes. The goal of this study is to investigate the trends of obesity amongst hospitalized patients with SCS therapy as well as healthcare utilization outcomes.

METHODS

Using the International Classification of Diseases (ICD) ninth and tenth procedure and diagnosis code, we investigated the National Inpatient Sample (NIS) for patients with SCS implants between 2011 and 2015. Patients received a diagnosis of obesity based on the following categories: class I, II and III obesity. Age, gender, and comorbid conditions of patients with obesity were matched 1:1 on propensity score to those without obesity diagnosis. Our primary outcome was defined as trend of obesity diagnosis. Our secondary outcome, healthcare utilization, included in-hospital cost, length of stay, and discharge location.

RESULTS

Between 2011 and 2015, a total of 3893 patients with SCS implants were identified (average age 56 ± 15 years, 58% female, 0.70 ± 1.1 Charlson Comorbidity Index, CCI). Of this cohort, 640 patients were identified as obese. The proportion of patients with obesity diagnosis increased significantly from 13.75% in 2011 to 19.36% in 2015 (p < 0.001). After 1:1 matching on propensity score, 597 patients with obesity were successfully matched to 597 patients without obesity. The total hospital cost for SCS patients with obesity (median $104,845, IQR $74,648-144,292) was not significantly different from patients without obesity diagnosis (median $111,092, IQR $68,990-145,459) (p = 0.161).

CONCLUSIONS

The data from our study suggests that there is an increasing rate of obesity diagnosis amongst patients with SCS therapy. However, there was no difference in healthcare utilization between patients with and without obesity. Additional studies may provide more insight into our findings.

Single arm prospective multicenter case series on the use of burst stimulation to improve pain and motor symptoms in Parkinson's disease

Background

In this study we analyze new clinical data in the use of spinal cord stimulation (SCS) for the treatment of pain and motor symptoms in patients with Parkinson's Disease (PD), as both a singular bioelectric therapy and as a salvage therapy after deep brain stimulation (DBS).

Methods

Fifteen patients were recruited and had percutaneous electrodes implanted at the level of the thoracic or cervical spine. Participants were set to one of three stimulation modes: continuous tonic stimulation, continuous Burst stimulation (40 Hz, 500 Hz, 1000 μs), or cycle mode (on time of 10-15 s, off time of 15-30 s) with Burst (40 Hz, 500 Hz, 1000 μs). Patients completed the Visual Analogue Scale (VAS), Unified Parkinson's Disease Rating Scale, Self-Rating Depression Scale, Hamilton Depression Rating Scale, Profile of Mood State, 10-meter walking test, and the Timed Up and Go (TUG).

Results

All patients experienced significant improvement in VAS scores with a mean reduction of 59% across all patients. Patients who chose the cycling burst stimulation parameter had an average 67% reduction in VAS scores, as compared to the continuous burst parameter group, which had an average 48% reduction in VAS scores. Seventy-three percent of patients experienced improvement in the 10-meter walk, with an average improvement of 12%. Sixty-four percent of patients experienced clinically relevant improvements in the TUG, with an average improvement of 21%.

Conclusions

This study points to the potential utility of SCS to address both pain and certain aspects of motor symptoms in PD patients who have and have not received DBS therapy.

[Spinal cord stimulation in the treatment of chronic pain]

Despite the numerous analgesic drugs, the prevalence of intractable neuropathic pain remains high making up about 5%. Intervention methods, including methods of chronic electrostimulation, are used to treat these patients. Spinal cord stimulation (SCS) is the most common surgical method worldwide that replaced destructive and ablation procedures. Currently, common tonic SCS, HF-10 stimulation and burst SCS are applied, and the choice of method is based on clinical and neurophysiological data. Also, the introduction of nanomaterial-enabled neural stimulation could significantly minimize surgery risk.

Neuromodulation With Burst and Tonic Stimulation Decreases Opioid Consumption: A Post Hoc Analysis of the Success Using Neuromodulation With BURST (SUNBURST) Randomized Controlled Trial

OBJECTIVE

The SUNBURST study was a prospective, multicenter, randomized crossover trial of a single device delivering burst and tonic spinal cord stimulation (SCS) for chronic trunk and/or limb pain. We performed a post hoc analysis of opioid consumption at baseline and after device implantation.

MATERIALS AND METHODS

After implantation, 100 patients were randomized to one mode (tonic or burst) for 12 weeks, and the other mode for the subsequent 12 weeks. After the crossover period (24 weeks), patients chose their preferred mode and were assessed for one year. We analyzed 69 patients who took opioid medication at baseline. The primary endpoint was opioid consumption in morphine milligram equivalents (MMEs) at baseline and 12 months postimplantation. Subgroup analysis included opioid consumption based on Center for Disease Control markers (<50, 50-90, 90-120, >120 MME/day) and stimulation mode preference.

RESULTS

Opioid consumption at 12 months was lower compared to baseline (53.94 vs. 79.19 MME, MD -25.25, 95% CI -43.77 to 6.73, p = 0.008). By 12 months, 11 of 69 patients (15.9%) discontinued all opioid (p = 0.001). Based on CDC dose markers, the proportion of patients taking >120 MME/day decreased by 61.7% at 12 months postintervention compared to baseline (p = 0.043). Forty-five of 69 patients (65.2%) preferred burst SCS while 15 of 69 patients (21.7%) preferred tonic SCS (p < 0.001).

CONCLUSION

A device delivering tonic and burst SCS was associated with decreased opioid consumption after 12 months in patients with chronic trunk and/or limb pain. The proportion of patients reporting the highest opioid intake (>120 MME/day) decreased to a lower CDC dose category by 61.7%, carrying important implications for those at highest risk for opioid-related substance use disorder, overdose, and death.

Changes in spinal cord hemodynamics reflect modulation of spinal network with different parameters of epidural stimulation

In this study functional ultrasound (fUS) imaging has been implemented to explore the local hemodynamics response induced by electrical epidural stimulation and to study real-time in vivo functional changes of the spinal cord, taking advantage of the superior spatiotemporal resolution provided by fUS. By quantifying the hemodynamics and electromyographic response features, we tested the hypothesis that the temporal hemodynamics response of the spinal cord to electrical epidural stimulation could reflect modulation of the spinal circuitry and accordingly respond to the changes in parameters of electrical stimulation. The results of this study for the first time demonstrate that the hemodynamics response to electrical stimulation could reflect a neural-vascular coupling of the spinal cord. Response in the dorsal areas to epidural stimulation was significantly higher and faster compared to the response in ventral spinal cord. Positive relation between the hemodynamics and the EMG responses was observed at the lower frequencies of epidural stimulation (20 and 40 Hz), which according to our previous findings can facilitate spinal circuitry after spinal cord injury, compared to higher frequencies (200 and 500 Hz). These findings suggest that different mechanisms could be involved in spinal cord hemodynamics changes during different parameters of electrical stimulation and for the first time provide the evidence that neural-vascular coupling of the spinal cord circuitry could be related to specific organization of spinal cord vasculature and hemodynamics.

Spinal cord stimulation in chronic pain: technical advances

Chronic severe pain results in a detrimental effect on the patient’s quality of life. Such patients have to take a large number of medications, including opioids, often without satisfactory effect, sometimes leading to medication abuse and the pain worsening. Spinal cord stimulation (SCS) is one of the most effective technologies that, unlike other interventional pain treatment methods, achieves long-term results in patients suffering from chronic neuropathic pain. The first described mode of SCS was a conventional tonic stimulation, but now the novel modalities (high-frequency and burst), techniques (dorsal root ganglia stimulations), and technical development (wireless and implantable pulse generator-free systems) of SCS are becoming more popular. The improvement of SCS systems, their miniaturization, and the appearance of new mechanisms for anchoring electrodes results in a significant reduction in the rate of complications and revision surgeries, and the appearance of new waves of stimulation allows not only to avoid the phenomenon of addiction, but also to improve the long-term results of chronic SCS. The purpose of this review is to describe the current condition of SCS and up-to-date technical advances.

Cost comparison among punctate midline myelotomy, intrathecal pain pump, and spinal cord epidural stimulator

Background:

Invasive pain procedures can be valuable tools to manage chronic pain. Here, we compared the costs of three procedures used to address chronic pain; punctate midline myelotomy (PMM), placement of a spinal cord stimulator (SCS), or placement of an intrathecal pain pump (ITPP).

Case Description:

This retrospective chart review yielded 9 patients with chronic pain syndromes; 3 had PMM, 3 had SCS, and 3 had ITPP procedures. Variables studied included; pain type, the procedures performed, and the cost of each procedure. The Wilcoxon rank-sum and one-way analysis of variance were used to compare the three groups (P < 0.05). PMM was performed for patients with chronic nonmalignant visceral pain and SCS was utilized for failed back syndrome, while ITPP was placed in two patients with chronic visceral cancer pain and one patient with chronic somatic cancer pain. The mean length of stay was significant shorter for SCS and PMM versus ITPP (e.g., 1, 3.6 ± 0.6 and 15 ± 5.6 days). The mean procedure costs were significantly higher for SCS versus PMM and ITPP (105,234, $71,087, and $79,333); for the latter PMM and ITPP, procedural costs were not significantly different.

Conclusion:

For the three pain procedures discussed in this report, PMM is the most cost-effective as it obviates the need for efficacy trials, and there are: no implant device costs, no medication refills, no maintenance costs, and no complication management costs.

Current Evidence Lacking to Guide Clinical Practice for Spinal Cord Stimulation in the Treatment of Neuropathic Pain in Spinal Cord Injury: A Review of the Literature and a Proposal for Future Study

BACKGROUND/OBJECTIVE

Chronic pain is commonly reported in individuals with spinal cord injuries (SCIs), with recent prevalence reported as high as 80%. Uncontrolled pain is known to decrease quality of life, attenuate mood, and impact sleep. Spinal cord stimulation (SCS) for the treatment of refractory pain was first used in the SCI population in 1972. To date there have been no randomized controlled trials examining the effect of SCS on neuropathic pain post-SCI. A literature review in 2009 identified 27 studies, the majority prior to 2000, that included at least 1 patient with SCI. Given the significant advancements in the field of SCS, this review examines the updated evidence of SCS for the treatment of neuropathic pain in individuals with SCI and provides guidance on future investigations.

METHODS

MEDLINE and EMBASE databases were searched. All published reports, case series, and clinical trials reviewing SCS for neuropathic pain that included at least 1 individual with SCI were included.

RESULTS

The initial search identified 376 reports, of which 22 met inclusion criteria, for a total of 69 patients. All reports were of very low quality. A majority of the reported patients were male, underwent tonic stimulation, and reportedly experienced improvement in pain and spasticity, with decreased use of pain medication.

CONCLUSIONS

The synthesized findings from primarily case studies support the safety of SCS in SCI with the suggestion of potential pain relief benefit; however, data from low-quality studies are insufficient for informing clinical practice. A well-designed, prospective clinical trial is proposed to further investigate this indication.

A Novel Approach in Spinal Cord Stimulation for Enhancing Gastric Motility: A Preliminary Study on Canines

Background/Aims

Gastroparesis is commonly seen in patients with diabetes and functional dyspepsia with no satisfactory therapies. Dysautonomia is one of the main reasons for the imbalanced motility. We hypothesized that spinal cord stimulation (SCS) is a viable therapy for gastroparesis via the autonomic modulation to improve gastric motility. The aim is to find an optimal method of SCS for treating gastroparesis.

Methods

Eight healthy-female dogs were implanted with a gastric cannula, a duodenal cannula, 2 multi-electrode spinal leads, and an implantable pulse generator. Gastric motility index (MI) was used to determine the best stimulation location/parameters of SCS. Optimized SCS was used to improve glucagon-induced gastroparesis.

Results

With fixed parameters, SCS at Thoracic 10 (T10) was found most effective for increasing gastric MI (37.8%, P = 0.013). SCS was optimized with different parameters (pulse width: 0.05–0.6 msec, frequency: 5–500 Hz, motor threshold: 30–90%) on T10. Our findings revealed that 0.5 msec, 20 Hz with 90% motor threshold at T10 were the best parameters in increasing MI. Glucagon significantly delayed gastric emptying, and this inhibitory effect was partially blocked by SCS. Gastric emptying at 120 minutes was 25.6% in the control session and 15.7% in glucagon session (P = 0.007 vs control), while it was 22.9% with SCS session (P = 0.041 vs glucagon). SCS with the optimal parameters was found to maximally enhance vagal activity and inhibit sympathetic activity assessed by the spectral analysis of heart rate variability.

Conclusions

SCS with optimized stimulation location and parameters improves gastric motility in healthy-dogs and accelerates gastric emptying impaired by glucagon via enhancing vagal activity.

Evaluation of MRI Issues for a New Wirelessly Powered, Spinal Cord Stimulation Lead With Receiver

OBJECTIVE. MRI is an imaging modality frequently ordered for patients with neuromodulation systems implanted for spinal cord stimulation. The purpose of this investigation was to evaluate MRI safety issues (magnetic field interactions, MRI-related heating, functional disturbances, and artifacts) for a new wirelessly powered lead with receiver used for SCS. MATERIALS AND METHODS. Lead samples underwent in vitro evaluation for MRI safety issues using standardized techniques. Magnetic field interactions (i.e., translational attraction and torque) and artifacts were tested at 3 T. MRI-related heating was performed at 1.5 T/64 MHz and 3 T/128 MHz using two different methods: numerical simulations with analytical modeling and physical testing. Possible functional disturbances were evaluated under exposures to 1.5-T/64-MHz and 3-T/128-MHz MRI conditions. RESULTS. The lead exhibited minor magnetic field interactions (22° deflection angle, no torque) at 3 T. The highest temperature change recorded at 1.5 T/64 MHz and 3 T/128 MHz was 3.8°C and 11.3°C, respectively. Exposures to MRI conditions did not damage or alter the functional aspects of the leads. The maximum artifact size seen on a gradient-echo pulse sequence extended approximately 10 mm relative to the size of the lead. CONCLUSION. The MRI tests performed on patients with the new lead with receiver revealed no substantial concerns with respect to the conditions that we provide in the safety guidelines that were based on the results of this investigation. Therefore, MRI examinations will result in acceptable heating when conducted at appropriate whole-body-averaged specific absorption rate levels (i.e., 2.0 W/kg at 1.5 T/64 MHz and 0.3 W/kg at 3 T/128 MHz, corresponding to adjusted temperature rises of 3.6°C and 1.2°C, respectively). Therefore, patients with this wirelessly powered lead and receiver implanted can safely undergo MRI examinations under specific conditions.

Sensor driven-position adaptive versus conventional spinal cord stimulation in failed back surgery syndrome: a retrospective case series

Background

Failed back surgery syndrome (FBSS) is a common problem affecting 20–40% of cases undergoing spine surgeries. Spinal cord stimulation (SCS) has been shown to be an efficient and relatively safe treatment in managing many intractable chronic pain syndromes.

Objectives

This study compares the efficacy and safety of MR-compatible sensor driven-position adaptive SCS and conventional SCS in treating FBSS.

Methods

This is a retrospective case series of 120 consecutive FBSS patients who underwent SCS between February 2011 and March 2018. Pain levels, analgesic/opioid use, and sleep problems were assessed before and 3 months after the procedure in patients who received either conventional SCS (group 1; n = 62) or sensor-driven position adaptive SCS (group 2; n = 34). The degree of patient satisfaction, the change in the activities of daily living (ADLs) together with the rate of complications were compared in both treatment groups.

Results

The two treatment groups were homogenous at baseline. Patients in both groups improved significantly regarding pain, opioid consumption, sleep, and ADLs. The magnitude of improvement was statistically higher in group 2. An absolute reduction of 6 points on the VAS in patients who received position adaptive SCS vs a 3.3 point reduction in conventional SCS cases (p < 0.0001). Half of the patients in group 2 (n = 17) showed excellent satisfaction after the procedure versus 14.5% of cases in group 1 (n = 9).

Conclusion

SCS is an efficient and reliable treatment in FBSS. MR-compatible sensor driven-position adaptive SCS can be a more effective treatment in this patient group.

Activation of the sciatic nerve evoked during epidural spinal cord stimulation in rodents

Aim

To validate the use of motor activation thresholds (MoT) to titrate stimulation amplitudes for spinal cord stimulation in rodent models.

Methods

We recorded thresholds for MoT and sciatic compound action potentials in ten Sprague-Dawley rats implanted with epidural electrodes. Strength duration curves were fitted to the threshold values.

Results

Activation thresholds were in the same order for both MoT and sciatic compound action potentials.

Conclusion

Many of the large, myelinated fibers traversing the dorsal columns in the rodent spine are activated at similar current levels to MoT. Epidural stimulation in rodents needs to be applied at amplitudes close to MoT to activate these axons.

Association Between Pain Scores and Successful Spinal Cord Stimulator Implantation

INTRODUCTION

Determining reduction in pain score during spinal cord stimulation (SCS) trial is important prior to permanent SCS implantation. However, this association remains elusive. We investigate the association between post-SCS pain scores and successful permanent SCS implants.

MATERIALS AND METHODS

This IRB-approved, retrospective study identified patients who underwent SCS trials and implantation. Predictive modeling with nonparametric regression and margins plot analysis was used to determine the threshold for post-SCS trial pain scores associated with successful permanent SCS implant (defined as >50% pain relief). Nonparametric sensitivity and specificity analysis was performed. p < 0.05 was considered significant.

RESULTS

Eighty-eight patients with SCS trials were retrospectively identified (57.95% female, median age 52.5 ± 15.5 years). Of the total cohort, 79% had successful permanent SCS implantation. Post-SCS trial pain scores less than or equal to 4.9 had greater than 50% probability of a successful permanent SCS implant (97.14% sensitivity, 44.44% specificity, ROC = 0.71). Post-SCS trial pain scores between 4 and 7 were associated with a significantly higher probability of a successful SCS implant among patients without spine surgery compared with those with a history of spine surgery. Compared with males, females with pain scores between 5 and 7 had a higher probability of a successful SCS implant.

CONCLUSION

Low pain scores after SCS trial are predictive of successful SCS implants with high sensitivity. Males and surgical patients with higher pain scores had a lower probability of successful SCS implant than their counterparts. Larger studies are needed to further elucidate this relationship.

Long-Term Reduction of Sacroiliac Joint Pain With Peripheral Nerve Stimulation

BACKGROUND

We recently demonstrated that 86% of the patients treated with peripheral nerve stimulation (PNS) for therapy-refractory sacroiliac joint (SIJ) pain were satisfied with the result after 1 year of treatment.

OBJECTIVE

To investigate the long-term (up to 4 years) response rate of this novel treatment.

METHODS

Sixteen consecutive patients with therapy-refractory SIJ pain were treated with PNS and followed for 4 years in 3 patients, 3 years in 6 patients, and 2 years in 1 patient. Quality of life, pain, and patient satisfaction were assessed using the Oswestry Disability Index 2.0, Visual Analog Scale (VAS), and International Patient Satisfaction Index.

RESULTS

Patients reported a pain reduction from 8.8 to 1.6 (VAS) at 1 year ( P < .001), and 13 of 14 patients (92.9%) rated the therapy as effective (International Patient Satisfaction Index score ≤ 2). At 2 years, average pain score was 1.9 ( P < .001), and 9 of 10 patients (90.0%) considered the treatment a success. At 3 years, 8 of 9 patients (88.9%) were satisfied with the treatment results, reporting an average VAS of 2.0 ( P < .005). At 4 years, 2 of 3 patients were satisfied with the treatment results.

CONCLUSION

We have shown for the first time that PNS is a successful long-term therapy for SIJ pain.

Immediate Abdominal Pain after Placement of Thoracic Paddle Leads for Spinal Cord Stimulation: A Case Series

BACKGROUND

Spinal cord stimulation (SCS) is a well-established treatment modality for chronic pain. Thoracic radiculopathy has been reported as a complication of SCS paddle lead implantation by several authors and commonly presents as abdominal pain.

METHODS

We performed a search of all patients who underwent either placement of a new epidural paddle lead electrode or revision of an epidural paddle lead electrode for SCS in the thoracic region from January 2017 to January 2018. We then investigated all cases of immediate postoperative abdominal pain.

RESULTS

We identified 7 patients who had immediate postoperative abdominal pain among 86 cases of epidural SCS procedures. Most patients were discharged on postoperative days 1-3. No patients required revisions or removals of their SCS for any reason.

CONCLUSIONS

We conclude that the etiology of immediate postoperative abdominal pain after thoracic paddle lead implantation for SCS is most likely thoracic radiculopathy. We hypothesize that small, transient epidural hematomas could be the cause of this thoracic radiculopathy. We argue that all patients with immediate postoperative abdominal pain and no other neurologic deficits after thoracic paddle lead implantation for SCS should first be treated conservatively with observation and pain management.

Permanent Paddle-lead Trial for Spinal Cord Stimulation

Objectives

A significant number of chronic pain patients rely on spinal cord stimulation (SCS) for treatment of their intractable pain. A screening trial using percutaneous electrodes is an integral step for predicting a successful treatment course with a permanent SCS system. Most of these trials are performed in an outpatient ambulatory surgical center and some in the office setting. However, there are select patients who are considered poor candidates for percutaneous trials. We present the initial report of patients who have received surgical implantation of permanent paddle-leads for SCS trials at our institution and show that this was a safe and effective alternative for our patients who could not undergo percutaneous trials. 

Methods

We retrospectively reviewed the hospital charts of 12 patients who underwent permanent surgically-implanted paddle-lead trials from 2014 to 2017. Success was considered positive with a 50% reduction in pain rating. If positive, patients were brought back to the operating room to have the implanted leads connected to an internalized pulse generator.   

Results

All 12 patients met the criteria for a successful trial. Only one patient had his SCS system surgically removed after nine months. None of our patients reported or returned with paddle-lead migrations or infections. 

Conclusions

We report that surgically-implanted paddle-lead trials were a safe and effective alternative to percutaneous trials in our patients who were deemed poor candidates for percutaneous trials. No complications occurred and all of our patients received a second surgery for internalization of the SCS system. Patients who have previously failed percutaneous trials may be false-negatives to SCS. 

Evaluation of an innovative spinal cord stimulator platform for the treatment of chronic pain

Spinal cord stimulation (SCS) is an ever-evolving therapy for the treatment of chronic pain. Currently, there are four main companies offering a variety of options for SCS. The Intellis™ system is the latest offering from Medtronic (MN, USA). Intellis offers the smallest implantable SCS pulse generator available and is capable of multiple different modes of stimulation, some of which can be run simultaneously. With an intrinsic accelerometer, the device is capable of sensing various patient positions and can automatically adjust stimulation intensity. Intellis also offers the most comprehensive MRI conditionality to date. Additionally, the new Samsung/Android^® (Seoul, South Korea) clinician programmer allows for easier programming than previous Medtronic programing systems. The programer can also generate patient activity and usage reports from implantable pulse generator data.

Treatment of glenohumeral arthritis pain utilizing spinal cord stimulation

Background:

Dorsal column stimulation may be utilized to treat non-neuropathic pain attributed to glenohumeral arthritis.

Case Description:

An 84-year-old female presented with right shoulder pain for 3 years. She was diagnosed with glenohumeral arthritis and a complete loss of the joint space. She was treated with a dorsal column stimulator, requiring the electrodes to be placed from the inferior aspect of C3 to the superior aspect of T1. Six weeks postoperatively, she reported >90% coverage of her shoulder pain, demonstrated increased right arm function, and a reduction in her use of narcotics.

Conclusion:

Dorsal column stimulation of C3–T1 proved to be an effective alternative treatment for drug-resistant glenohumeral arthritis in an 84-year-old female with a complete loss of the joint space.