Analysis of spinal canal diameter in the placement of thoracic spinal cord stimulator paddle leads.

BACKGROUND: Neurologic deficit is known as a rare complication of thoracic spinal cord stimulator (SCS) paddle lead implantation, but many believe its incidence after SCS paddle lead placement is under-reported. It is possible that imaging characteristics may be used to help predict safe paddle lead placement. OBJECTIVE: This imaging study was undertaken to determine the minimum canal diameter required for safe paddle lead placement. METHODS: Patients who underwent thoracic laminotomy for new SCS paddle lead placement from January 2018 to March 2023 were identified retrospectively. Preoperative thoracic canal diameter was measured in the sagittal plane perpendicular to the disc space from T5/6 to T11/12. These thoracic levels were chosen because they span the most common levels targeted for SCS placement. Patients with and without new neurologic deficits were compared using a Mann-Whitney U-test. RESULTS: Of 185 patients initially identified, 180 had thoracic imaging available for review. One (0.5%) and 2 (1.1%) of 185 patients complained of permanent and transient neurologic deficit after thoracic SCS placement, respectively. Patients with neurologic deficits had average canal diameters of <11 mm. The average canal diameter of patients with and without neurologic deficits was 10.2 mm (range 6.1-12.9 mm) and 13.0 mm (range 5.9-20.2), respectively (p < 0.0001). CONCLUSION: Postoperative neurologic deficit is an uncommon complication after thoracic laminotomy for SCS paddle lead placement. The authors recommend ensuring a starting thoracic canal diameter of at least 12 mm to accommodate a SCS paddle lead measuring 2 mm thick to ensure a final diameter of >10 mm. If canal diameter is <12 mm, aggressive undercutting of the lamina, a second laminotomy, or placement of smaller SCS wire leads should be considered.

Durable multimodal and holistic response for physiologic closed-loop spinal cord stimulation supported by objective evidence from the EVOKE double-blind randomized controlled trial.

INTRODUCTION: Chronic pain patients may experience impairments in multiple health-related domains. The design and interpretation of clinical trials of chronic pain interventions, however, remains primarily focused on treatment effects on pain intensity. This study investigates a novel, multidimensional holistic treatment response to evoked compound action potential-controlled closed-loop versus open-loop spinal cord stimulation as well as the degree of neural activation that produced that treatment response. METHODS: Outcome data for pain intensity, physical function, health-related quality of life, sleep quality and emotional function were derived from individual patient level data from the EVOKE multicenter, participant, investigator, and outcome assessor-blinded, parallel-arm randomized controlled trial with 24 month follow-up. Evaluation of holistic treatment response considered whether the baseline score was worse than normative values and whether minimal clinical important differences were reached in each of the domains that were impaired at baseline. A cumulative responder score was calculated to reflect the total minimal clinical important differences accumulated across all domains. Objective neurophysiological data, including spinal cord activation were measured. RESULTS: Patients were randomized to closed-loop (n=67) or open-loop (n=67). A greater proportion of patients with closed-loop spinal cord stimulation (49.3% vs 26.9%) were holistic responders at 24-month follow-up, with at least one minimal clinical important difference in all impaired domains (absolute risk difference: 22.4%, 95% CI 6.4% to 38.4%, p=0.012). The cumulative responder score was significantly greater for closed-loop patients at all time points and resulted in the achievement of more than three additional minimal clinical important differences at 24-month follow-up (mean difference 3.4, 95% CI 1.3 to 5.5, p=0.002). Neural activation was three times more accurate in closed-loop spinal cord stimulation (p<0.001 at all time points). CONCLUSION: The results of this study suggest that closed-loop spinal cord stimulation can provide sustained clinically meaningful improvements in multiple domains and provide holistic improvement in the long-term for patients with chronic refractory pain. TRIAL REGISTRATION NUMBER: NCT02924129.

Neuromodulation for the management of chronic pelvic pain syndromes: A systematic review.

BACKGROUND: Chronic pelvic pain is a burdensome condition that involves multiple medical sub-specialties and is often difficult to treat. Sacral stimulation for functional bladder disease has been well established, but little large-scale evidence exists regarding utilization of other neuromodulation techniques to treat chronic pelvic pain. Emerging evidence does suggest that neuromodulation is a promising treatment, and we aim to characterize the use and efficacy of such techniques for treating chronic pelvic pain syndromes. MATERIALS AND METHODS: A systematic review of the literature demonstrating the treatment of chronic pelvic pain syndromes with neuromodulation. Abstracts were reviewed and selected for inclusion, including case series, prospective studies, and randomized controlled trials (RCTs). Case studies and publications in abstract only were not included. The reporting for this systematic review follows Preferred Reporting Items for Systematic Reviews and Meta-Analysis (PRISMA). The literature search was performed using MEDLINE, Embase, Cochrane Library, PubMed, CINAHL, and Scopus. RESULTS: A total of 50 studies were included in this review, three of which were randomized controlled trials, and the remaining were prospective and retrospective case series. The range of pelvic pain conditions treated included interstitial cystitis, peripheral neuralgia, pudendal neuralgia, gastrointestinal pain, urogenital pain, sacroiliac joint pain, and visceral chronic pelvic pain. We reported on outcomes involving pain, functionality, psychosocial improvement, and medication reduction. CONCLUSIONS: Neuromodulation is a growing treatment for various chronic pain syndromes. Peripheral nerve stimulation was the least studied form of stimulation. Posterior tibial nerve stimulation appears to offer short-term benefit, but long-term results are challenging. Sacral nerve stimulation is established for use in functional bladder syndromes and appears to offer pain improvement in these patients as well. Dorsal root ganglion stimulation and spinal cord stimulation have been used for a variety of conditions with promising results. Further studies of homogeneous patient populations are necessary before strong recommendations can be made at this time, although pooled analysis may also be impactful.

Dynamic electrical stimulation enhances the recruitment of spinal interneurons by corticospinal input.

Highly varying patterns of electrostimulation (Dynamic Stimulation, DS) delivered to the dorsal cord through an epidural array with 18 independent electrodes transiently facilitate corticospinal motor responses, even after spinal injury. To partly unravel how corticospinal input are affected by DS, we introduced a corticospinal platform that allows selective cortical stimulation during the multisite acquisition of cord dorsum potentials (CDPs) and the simultaneous supply of DS. Firstly, the epidural interface was validated by the acquisition of the classical multisite distribution of CDPs and their input-output profile elicited by pulses delivered to peripheral nerves. Apart from increased EMGs, DS selectively increased excitability of the spinal interneurons that first process corticospinal input, without changing the magnitude of commands descending from the motor cortex, suggesting a novel correlation between muscle recruitment and components of cortically-evoked CDPs. Finally, DS increases excitability of post-synaptic spinal interneurons at the stimulation site and their responsiveness to any residual supraspinal control, thus supporting the use of electrical neuromodulation whenever the motor output is jeopardized by a weak volitional input, due to a partial disconnection from supraspinal structures and/or neuronal brain dysfunctions.

Case report: Dorsal root ganglion stimulator lead fracture.

BACKGROUND: One of the unique advances in neuromodulation for chronic pain has been spinal cord stimulators (SCS) and dorsal root ganglion stimulators (DRG-S). These devices have aided in conditions such as neuropathic pain, complex regional pain syndromes, failed back surgery, and peripheral neuropathies. With these benefits, however, complications from implantable stimulators have included lead fractures and migration. The authors reviewed a lead migration, kinking, and subsequent fracture event involving a patient with complex regional pain syndrome (CRPS) II, who was treated with a DRG-S. CASE PRESENTATION: The case report follows this patient, from their past medical history to assessment of appropriate qualifications for neuromodulation, to successful surgical placement, to follow-up care. The authors further monitored assessment of inefficacy of pain relief, and identification of lead migration and kinking through imaging. In the process of removal, due to lead stress, lead fracturing occurred. After lead removal, the leads were fully replaced, and the patient was followed up and experienced improved pain relief. CONCLUSION: The case report assesses probable mechanisms of lead fracture and considerations for physicians for future assessment and triage of neuromodulation efficacy.

Current Neurostimulation Therapies for Chronic Pain Conditions.

PURPOSE OF REVIEW: Neurostimulation treatment options have become more commonly used for chronic pain conditions refractory to these options. In this review, we characterize current neurostimulation therapies for chronic pain conditions and provide an analysis of their effectiveness and clinical adoption. This manuscript will inform clinicians of treatment options for chronic pain. RECENT FINDINGS: Non-invasive neurostimulation includes transcranial direct current stimulation and repetitive transcranial magnetic stimulation, while more invasive options include spinal cord stimulation (SCS), peripheral nerve stimulation (PNS), dorsal root ganglion stimulation, motor cortex stimulation, and deep brain stimulation. Developments in transcranial direct current stimulation, repetitive transcranial magnetic stimulation, spinal cord stimulation, and peripheral nerve stimulation render these modalities most promising for the alleviating chronic pain. Neurostimulation for chronic pain involves non-invasive and invasive modalities with varying efficacy. Well-designed randomized controlled trials are required to delineate the outcomes of neurostimulatory modalities more precisely.

Should we Oppose or Combine Waveforms for Spinal Cord Stimulation in PSPS-T2 Patients? A Prospective Randomized Crossover Trial (MULTIWAVE Study).

Refractory persistent spinal pain syndrome after surgery (PSPS-T2) can be successfully addressed by spinal cord stimulation (SCS). While conventional stimulation generates paresthesia, recent systems enable the delivery of paresthesia-free stimulation. Studies have claimed non-inferiority/superiority of selected paresthesia-free stimulation compared with paresthesia-based stimulation, but the comparative efficacy between different waveforms still needs to be determined in a given patient. We designed a randomized controlled 3-month crossover trial to compare pain relief of paresthesia-based stimulation versus high frequency versus burst in 28 PSPS-T2 patients implanted with multiwave SCS systems. Our secondary objectives were to determine the efficacy of these 3 waveforms on pain surface, quality of life, functional capacity, psychological distress, and validated composite multidimensional clinical response index to provide holistic comparisons at 3-, 6-, 9-, and 15-month post-randomization. The preferred stimulation modality was documented during the follow-up periods. No difference between the waveforms was observed in this study (P = .08). SCS led to significant pain relief, quality of life improvement, improvement of multidimensional clinical response index, and of all other clinical outcomes at all follow-up visits. Forty-four percent of the patients chose to keep the paresthesia-based stimulation modality after the 15-month follow-up period. By giving the possibility to switch and/or to combine several waveforms, the overall rate of SCS responders further increased with 25%. In this study, high frequency or burst do not appear superior to paresthesia-based stimulation, wherefore paresthesia-based stimulation should still be considered as a valid option. However, combining paresthesia-based stimulation with paresthesia-free stimulation, through personalized multiwave therapy, might significantly improve SCS responses. PERSPECTIVE: This article assesses clinical SCS efficacy on pain relief, by comparing paresthesia-based stimulation and paresthesia-free stimulation (including high frequency and burst) modalities in patient presenting with PSPS-T2. Switching and/or combining waveforms contribute to increasing the global SCS responders rate.

Failed Back Surgery Syndrome: No Longer a Surgeon's Defeat-A Narrative Review.

The introduction of the term Persistent Spinal Pain Syndrome (PSPS-T1/2), replacing the older term Failed Back Surgery Syndrome (FBSS), has significantly influenced our approach to diagnosing and treating post-surgical spinal pain. This comprehensive review discusses this change and its effects on patient care. Various diagnostic methods are employed to elucidate the underlying causes of back pain, and this information is critical in guiding treatment decisions. The management of PSPS-T1/2 involves both causative treatments, which directly address the root cause of pain, and symptomatic treatments, which focus on managing the symptoms of pain and improving overall function. The importance of a multidisciplinary and holistic approach is emphasized in the treatment of PSPS-T1/2. This approach is patient-centered and treatment plans are customized to individual patient needs and circumstances. The review concludes with a reflection on the impact of the new PSPS nomenclature on the perception and management of post-surgical spinal pain.

Novel implantation technique for pudendal nerve peripheral nerve stimulation for treatment of chronic pelvic pain.

BACKGROUND: Chronic pelvic pain (CPP) is a pervasive, difficult to treat condition affecting up to 26% of the global female and 8.2% of the global male population. Considered a form of chronic regional pain syndrome (CRPS), it is medically complex and often refractory to multimodal management. Neuromodulation has become increasingly popular in treatment of chronic neuropathic pain conditions, including CPP and CRPS. Dorsal column spinal cord stimulation and dorsal root ganglion stimulation have had some success for managing CPP meanwhile peripheral nerve stimulators (PNS) have been suggested as another viable option. However, few studies in the literature have reported successful use of PNS in treatment of CPP. Here, we detail a possible technique for pudendal PNS lead placement for management of CPP. METHOD: This article describes a novel cephalad to caudad fluoroscopic guided technique for pudendal nerve PNS lead placement and implantation. RESULTS: A cephalad to caudal-medial fluoroscopic guided approach as described within to successfully implant a percutaneous pudendal nerve PNS for management of CPP. CONCLUSIONS: The pudendal nerve PNS lead placement technique noted within can be used to avoid many of the important neurovascular structures near the pelvic outlet. Further studies are needed to validate the safety and efficacy of this therapy modality but it may be a viable management option for patients with medically refractory CPP.

Six-Month Follow-up of a Trial of Spinal Cord Burst Stimulation vs Placebo Stimulation and Disability in Patients With Chronic Radicular Pain After Lumbar Spine Surgery.

This follow-up study examines back pain­related disability at 6 months following a randomized trial of spinal cord burst stimulation for chronic radicular pain after lumbar spine surgery.

Perioperative and anesthetic considerations for the management of neuromodulation systems.

The use of neuromodulation systems is increasing for the treatment of various pathologies ranging from movement disorders to urinary incontinence to chronic pain syndromes. While the type of neuromodulation devices varies, they are largely categorized as intracranial (eg, deep brain stimulation), neuraxial (eg, spinal cord stimulation, dorsal root ganglion stimulation, and intrathecal drug delivery systems), or peripheral (eg, sacral nerve stimulation and peripheral nerve stimulation) systems. Given the increasing prevalence of these systems in the overall population, it is important for anesthesiologists, surgeons, and the perioperative healthcare team to familiarize themselves with these systems and their unique perioperative considerations. In this review, we explore and highlight the various neuromodulation systems, their general perioperative considerations, and notable special circumstances for perioperative management.

Role of peripheral nerve stimulation in treating chronic neuropathic pain: an international focused survey of pain medicine experts.

Interventional pain management (IPM) options for refractory neuropathic pain (NP) have recently increased with availability of peripheral nerve stimulation (PNS) equipment and expertise. Given a lack of high-quality evidence and guidelines on this topic, we sought to understand the perception of physicians with expertise in treating NP regarding IPM and the role of PNS. We emailed a survey in March 2022 to international NP experts including pain medicine physicians, researchers, and leaders of 11 professional pain societies. No representatives from vendors of PNS systems were included in the design of the survey nor as respondents. Among 24 respondents (67% of those contacted), the distal common peroneal, tibial, and sural nerves were most frequently targeted (60%) with PNS. Persistent postsurgical pain of more than 3 months was the most common indication for PNS (84%). The aggregate NP treatment algorithm in order of median rank was non-opioid medications as first line, IPM including epidural/perineural steroid injections tied with transcutaneous electrical nerve stimulation as second line, pulsed radiofrequency (RF) tied with RF ablation/denervation as third line, temporary then permanent PNS as fourth line, followed by spinal cord stimulation, opioids, cryoablation, botulinum, peripheral nerve field stimulation, intrathecal targeted drug delivery, and others. Before offering PNS, 12 respondents (50%) indicated their preference for trialing non-neuromodulation treatments for 1-3 months. Twenty-two respondents (92%) agreed PNS should be offered early in the treatment of neuropathic pain. The most common barriers to PNS use were cost, lack of high-quality evidence in support of its use, lack of exposure to PNS in training programs, and lack of familiarity with the use of ultrasound guidance. PNS appears to have an increasing role in the treatment of NP but more research is needed on the outcomes of PNS to elucidate its role.

Proportion of clinical holistic responders in patients with persistent spinal pain syndrome type II treated by subthreshold spinal cord stimulation compared to best medical treatment: a study protocol for a multicentric randomised controlled trial (TRADITION).

BACKGROUND: Integrating information on bodily functions, pain intensity and quality of life into one composite measure of a holistic responder has recently been proposed as a useful method to evaluate treatment efficacy of spinal cord stimulation (SCS) in patients with therapy-refractory persistent spinal pain syndrome type II (PSPS-T2). Previous studies already demonstrated the efficacy of standard SCS over best medical treatment (BMT) and the superiority of new subthreshold (i.e. paresthesia free) SCS paradigms compared to standard SCS. Nevertheless, the efficacy of subthreshold SCS compared to BMT has not yet been investigated in patients with PSPS-T2, neither with unidimensional outcomes nor with a composite measure. The current objective is to examine whether subthreshold SCS, compared to BMT, provided to patients with PSPS-T2 results in a different proportion of clinical holistic responders (as composite measure) at 6 months. METHODS: A two-arm multicentre randomised controlled trial will be conducted whereby 114 patients will be randomised (1:1) to (a) BMT or (b) paresthesia-free SCS. After a follow-up period of 6 months (primary time endpoint), patients receive the opportunity to cross over towards the other treatment group. The primary outcome is the proportion of clinical holistic responders at 6 months (i.e. a composite measure of pain intensity, medication, disability, health-related quality of life and patient satisfaction). The secondary outcomes are work status, self-management, anxiety, depression and healthcare expenditure. DISCUSSION: Within the TRADITION project, we propose to shift the focus from a unidimensional outcome measure towards a composite measure as primary outcome measure to evaluate the efficacy of currently used subthreshold SCS paradigms. The lack of methodologically rigorous trials exploring the clinical efficacy and socio-economic consequences of subthreshold SCS paradigms is pressing, especially in light of the growing burden of PSPS-T2 on the society. TRIAL REGISTRATION: ClinicalTrials.gov NCT05169047. Registered on December 23, 2021.

Holistic Treatment Response: An International Expert Panel Definition and Criteria for a New Paradigm in the Assessment of Clinical Outcomes of Spinal Cord Stimulation.

BACKGROUND: Treatment response to spinal cord stimulation (SCS) is focused on the magnitude of effects on pain intensity. However, chronic pain is a multidimensional condition that may affect individuals in different ways and as such it seems reductionist to evaluate treatment response based solely on a unidimensional measure such as pain intensity. AIM: The aim of this article is to add to a framework started by IMMPACT for assessing the wider health impact of treatment with SCS for people with chronic pain, a "holistic treatment response". DISCUSSION: Several aspects need consideration in the assessment of a holistic treatment response. SCS device data and how it relates to patient outcomes, is essential to improve the understanding of the different types of SCS, improve patient selection, long-term clinical outcomes, and reproducibility of findings. The outcomes to include in the evaluation of a holistic treatment response need to consider clinical relevance for patients and clinicians. Assessment of the holistic response combines two key concepts of patient assessment: (1) patients level of baseline (pre-treatment) unmet need across a range of health domains; (2) demonstration of patient-relevant improvements in these health domains with treatment. The minimal clinical important difference (MCID) is an established approach to reflect changes after a clinical intervention that are meaningful for the patient and can be used to identify treatment response to each individual domain. A holistic treatment response needs to account for MCIDs in all domains of importance for which the patient presents dysfunctional scores pre-treatment. The number of domains included in a holistic treatment response may vary and should be considered on an individual basis. Physiologic confirmation of therapy delivery and utilisation should be included as part of the evaluation of a holistic treatment response and is essential to advance the field of SCS and increase transparency and reproducibility of the findings.

High-frequency (10 kHz) spinal cord stimulation (SCS) as a salvage therapy for failed traditional SCS: A narrative review of the available evidence.

INTRODUCTION: Traditional spinal cord stimulation (t-SCS) has been used to treat chronic pain for over 50 years. However, up to 30% of patients undergo explant, with the main indication being loss of efficacy (LoE), and few alternative treatment options exist for these patients. Strategies to mitigate LoE commonly include conversion to another type of SCS (termed 'salvage' or 'rescue'). This review summarizes the existing literature concerning the efficacy and safety of 10 kHz SCS as a salvage therapy. METHODS: We searched PubMed, the Cochrane Library, ClinicalTrials.gov, and other sources between January 2009 and April 2021. Records were retained if the authors reported clinical outcomes with a minimum of ≥ 3 months of follow-up in patients implanted with a Senza® 10 kHz SCS system in an effort to treat t-SCS LoE. RESULTS: Ten articles were eligible for inclusion, reporting 3 prospective studies and 7 retrospective reviews. In the single study that salvaged patients without a repeat trial prior to surgery, 81% of patients were responders (≥ 50% pain relief from baseline), with mean pain relief of 60%. Among repeat-trial studies, the responder rate ranged from 46% to 80%, and mean pain relief from 47% to 68%. No unanticipated therapy-related safety issues were reported among the included articles. CONCLUSION: Preliminary data suggest that chronic back and/or leg pain patients with t-SCS LoE can experience improved and durable pain relief after conversion to 10 kHz SCS. However, additional research is needed to define predictors of success and establish whether salvage without a repeat trial is a viable conversion method.

Gradation of Clinical Holistic Response as New Composite Outcome to Evaluate Success in Spinal Cord Stimulation Studies for Pain.

INTRODUCTION: The most prominent outcome measurement in the field of neuromodulation is pain relief. Nevertheless, the number of studies that rely on composite outcomes has increased. The aims of this study are twofold: (1) to evaluate which measures are important to include in a composite outcome and (2) to develop this new composite outcome to evaluate the degree of being a clinical holistic responder with a corresponding minimal clinical important difference (MCID). MATERIALS AND METHODS: Data from patients with persistent spinal pain syndrome type 2 treated with High-Dose Spinal Cord Stimulation (HD-SCS) were used. Pain intensity for low back and leg pain, disability, health-related quality of life, medication use, and patient satisfaction were measured at baseline and after 12 months of HD-SCS. Exploratory and Confirmatory Factor Analyses were used to evaluate which measures should be included in the composite outcome. Anchor-based and distribution-based methods were applied to determine the MCID of the newly developed outcome measurement. RESULTS: A three-factor model was the most appropriate for this data set, in which leg pain intensity, EQ5D VAS, and disability had the largest loading on these factors. A clinical holistic outcome was created with a total score ranging from 0 (=better [no pain, no disability, and perfect health status]) to 300 (=worse [maximal pain, maximal disability, and worst health status]). The MCID value based on an absolute change score from baseline up to 12 months of HD-SCS was 87.97. When calculating with percentage changes, a MCID value of 48.4% was revealed. CONCLUSIONS: This new composite outcome evaluating the degree of deviation from being a holistic responder is a step toward a meaningful, overall outcome assessment for patients who are treated with SCS. Further studies to evaluate the psychometric properties and the generalizability toward other patient populations still need to be performed.