Safety and efficacy of spinal cord stimulation for the treatment of chronic pain: a 20-year literature review

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.

Direct measurement of oxygen reduction reactions at neurostimulation electrodes

Objective. Electric stimulation delivered by implantable electrodes is a key component of neural engineering. While factors affecting long-term stability, safety, and biocompatibility are a topic of continuous investigation, a widely-accepted principle is that charge injection should be reversible, with no net electrochemical products forming. We want to evaluate oxygen reduction reactions (ORR) occurring at different electrode materials when using established materials and stimulation protocols.Approach. As stimulation electrodes, we have tested platinum, gold, tungsten, nichrome, iridium oxide, titanium, titanium nitride, and poly(3,4-ethylenedioxythiophene):poly(styrene sulfonate). We use cyclic voltammetry and voltage-step amperometry in oxygenated versus inert conditions to establish at which potentials ORR occurs, and the magnitudes of diffusion-limited ORR currents. We also benchmark the areal capacitance of each electrode material. We use amperometric probes (Clark-type electrodes) to quantify the O₂and H₂O₂concentrations in the vicinity of the electrode surface. O₂and H₂O₂concentrations are measured while applying DC current, or various biphasic charge-balanced pulses of amplitude in the range 10-30µC cm^-2/phase. To corroborate experimental measurements, we employ finite element modelling to recreate 3D gradients of O₂and H₂O₂.Main results. All electrode materials support ORR and can create hypoxic conditions near the electrode surface. We find that electrode materials differ significantly in their onset potentials for ORR, and in the extent to which they produce H₂O₂as a by-product. A key result is that typical charge-balanced biphasic pulse protocols do lead to irreversible ORR. Some electrodes induce severely hypoxic conditions, others additionally produce an accumulation of hydrogen peroxide into the mM range.Significance. Our findings highlight faradaic ORR as a critical consideration for neural interface devices and show that the established biphasic/charge-balanced approach does not prevent irreversible changes in O₂concentrations. Hypoxia and H₂O₂can result in different (electro)physiological consequences.

Chronic electrical stimulation of peripheral nerves via deep-red light transduced by an implanted organic photocapacitor

Implantable devices for the wireless modulation of neural tissue need to be designed for reliability, safety and reduced invasiveness. Here we report chronic electrical stimulation of the sciatic nerve in rats by an implanted organic electrolytic photocapacitor that transduces deep-red light into electrical signals. The photocapacitor relies on commercially available semiconducting non-toxic pigments and is integrated in a conformable 0.1-mm³ thin-film cuff. In freely moving rats, fixation of the cuff around the sciatic nerve, 10 mm below the surface of the skin, allowed stimulation (via 50-1,000-μs pulses of deep-red light at wavelengths of 638 nm or 660 nm) of the nerve for over 100 days. The robustness, biocompatibility, low volume and high-performance characteristics of organic electrolytic photocapacitors may facilitate the wireless chronic stimulation of peripheral nerves.

Cervical epidural abscess due to implantation of a spinal cord stimulation lead

Spinal cord stimulation (SCS) for intractable pain syndromes has become a pillar of modern pain management. Common complications include lead migration, implant infection, cerebral spinal fluid leak, and lead fracture. Spinal epidural abscess due to spinal cord stimulator implantation is a very rare occurrence with only two cases reported in the literature so far. We present an illustrative case and discuss the pathophysiology and best clinical management for this very rate entity.

Spinal Cord Stimulation to Treat Unresponsive Cancer Pain: A Possible Solution in Palliative Oncological Therapy

(1) Background: Treatment of cancer-related pain is still challenging, and it can be managed by both medical and interventional therapies. Spinal Cord Stimulation (SCS) is a minimally invasive technique, and its use is rapidly increasing in the treatment of chronic pain. (2) Materials and Methods: Our study aims to perform a review of the pertinent literature about current evidences in cancer pain treatment by Spinal Cord Stimulation. Moreover, we created a database based on case reports or case series (18 studies) in the literature. We analyzed a clinical group of oncological patients affected by intractable pain undergoing SCS implantation, focusing on outcome. (3) Results: The analysis of the 18 included studies in our series has shown a reduction in painful symptoms in 48 out of 56 treated patients (87.51%); also 53 out of 56 patients (96.64%) have shown an improvement in their Quality of Life (QoL). (4) Conclusions: Spinal Cord Stimulation can be considered an efficient method in the treatment of cancer-related pain. However, literature regarding SCS for the treatment of cancer-related pain is largely represented by case reports and small case series, with no effective population studies or Randomized Controlled Trials demonstrating the efficacy and the level of evidence. Further prospective studies are needed.

Mitigating Spinal Cord Stimulator Lead Migration Complications in Minimally Invasive Spine Surgery: Technical Note

Spinal Cord Stimulators (SCS) are a nonpharmacologic chronic pain management treatment modality that is well-validated and cost-effective within the surgeon’s armamentarium. The reported complication rates are between 5.3% to 40%, most commonly secondary to mechanical hardware failure. The most common mechanical complication is lead migration, which necessitates second surgery. The purpose of this technical note is to describe a minimally invasive spine surgery (MISS) implantation technique we believe to be more resilient to lead migration. We present a stepwise technique for SCS implantation with a maxillofacial screw and washer failsafe.

Contralateral and Lateral Views: Analysis of the Technical Aspects of Spinal Cord Stimulator Lead Insertion

Background

Spinal cord stimulation (SCS) is an established treatment modality for neuropathic pain. The critical part of this technique is safe access to the epidural space for lead placement. There have been innovations in radiological views, improving access to the epidural space.

Objectives

This study analyzes the adoption of these technical advantages in daily practice

Methods

We conducted a survey of members in the Spine Intervention Society and American Society of Regional Anesthesia in regard to the practice patterns in SCS therapy. Here we present our findings regarding the use of contralateral oblique (CLO) and lateral views as well direct upper thoracic or cervicothoracic access for SCS lead insertion

Results

A total of 195 unique responses were received between March 20, 2020 and June 26, 2020. Forty-five percent of respondents “always used” the lateral view technique while 15% “always used” CLO view for SCS lead insertion. Overall, sixty-five percent of respondents used the CLO view with varying frequency. Cervical and upper thoracic approach for cervical SCS lead placement is always or often used by 66.8% of the respondents.

Conclusions

A depth view (CLO or lateral) is always used by only 45 - 60% of the respondents and CLO view has been rapidly adopted in clinical practice for SCS lead insertion. Direct cervicothoracic and upper thoracic is the preferred approach for cervical lead placement by the majority.

Ethical Considerations in the Implantation of Neuromodulatory Devices

OBJECTIVES

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

MATERIALS AND METHODS

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

RESULTS

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

CONCLUSIONS

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

The Challenge of Converting "Failed Spinal Cord Stimulation Syndrome" Back to Clinical Success, Using SCS Reprogramming as Salvage Therapy, through Neurostimulation Adapters Combined with 3D-Computerized Pain Mapping Assessment: A Real Life Retrospective Study

While paresthesia-based Spinal Cord Stimulation (SCS) has been proven effective as treatment for chronic neuropathic pain, its initial benefits may lead to the development of "Failed SCS Syndrome' (FSCSS) defined as decrease over time related to Loss of Efficacy (LoE) with or without Loss of Coverage (LoC). Development of technologies associating new paresthesia-free stimulation waveforms and implanted pulse generator adapters provide opportunities to manage patients with LoE. The main goal of our study was to investigate salvage procedures, through neurostimulation adapters, in patients already implanted with SCS and experiencing LoE. We retrospectively analyzed a cohort of patients who were offered new SCS programs/waveforms through an implanted adapter between 2018 and 2021. Patients were evaluated before and at 1-, 3-, 6- and 12-month follow-ups. Outcomes included pain intensity rating with a Visual Analog Scale (VAS), pain/coverage mappings and stimulation preferences. Last follow-up evaluations (N = 27) showed significant improvement in VAS (p = 0.0001), ODI (p = 0.021) and quality of life (p = 0.023). In the 11/27 patients with LoC, SCS efficacy on pain intensity (36.89%) was accompanied via paresthesia coverage recovery (55.57%) and pain surface decrease (47.01%). At 12-month follow-up, 81.3% preferred to keep tonic stimulation in their waveform portfolio. SCS conversion using adapters appears promising as a salvage solution, with an emphasis on paresthesia recapturing enabled via spatial retargeting. In light of these results, adapters could be integrated in SCS rescue algorithms or should be considered in SCS rescue.

Clinical Outcomes after Spinal Cord Stimulation According to Pain Characteristics

Objective

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

Methods

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

Results

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

Conclusion

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

The Neurostimulation Appropriateness Consensus Committee (NACC): Recommendations for Surgical Technique for Spinal Cord Stimulation

INTRODUCTION

The field of neurostimulation for the treatment of chronic pain is a rapidly developing area of medicine. Although neurostimulation therapies have advanced significantly as a result of technologic improvements, surgical planning, device placement, and postoperative care are of equal importance to optimize outcomes. This Neurostimulation Appropriateness Consensus Committee (NACC) project intends to provide evidence-based guidance for these often-overlooked areas of neurostimulation practice.

MATERIALS AND METHODS

Authors were chosen based on their clinical expertise, familiarity with the peer-reviewed literature, research productivity, and contributions to the neuromodulation literature. Section leaders supervised literature searches of MEDLINE, BioMed Central, Current Contents Connect, Embase, International Pharmaceutical Abstracts, Web of Science, Google Scholar, and PubMed from the last NACC publication in 2017 to the present. Identified studies were graded using the United States Preventive Services Task Force criteria for evidence and certainty of net benefit. Recommendations are based on evidence strength and consensus when evidence was scant.

RESULTS

This NACC project provides guidance on preoperative assessment, intraoperative techniques, and postoperative management in the form of consensus points with supportive evidence. These results are based on grade of evidence, strength of consensus, and expert opinion.

CONCLUSIONS

The NACC has given guidance for a surgical plan that encompasses the patient journey from the planning stage through the surgical experience and postoperative care. The overall recommendations are designed to improve efficacy and the safety of patients undergoing these neuromodulation procedures and are intended to apply throughout the international community.

Comparison of Spinal Cord Stimulation vs. Dorsal Root Ganglion Stimulation vs. Association of Both in Patients with Refractory Chronic Back and/or Lower Limb Neuropathic Pain: An International, Prospective, Randomized, Double-Blinded, Crossover Trial (BOOST-DRG Study)

While spinal cord stimulation (SCS) is a well-established therapy to address refractory persistent spinal pain syndrome after spinal surgery (PSPS-T2), its lack of spatial selectivity and reported discomfort due to positional effects can be considered as significant limitations. As alternatives, new waveforms, such as burst stimulation and different spatial neural targets, such as dorsal root ganglion stimulation (DRGS), have shown promising results. Comparisons between DRGS and standard SCS, or their combination, have never been studied on the same patients. "BOOST DRG" is the first prospective, randomized, double-blinded, crossover study to compare SCS vs. DRGS vs. SCS+DRGS. Sixty-six PSPS-T2 patients will be recruited internationally in three centers. Before crossing over, patients will receive each stimulation modality for 1 month, using tonic conventional stimulation. After 3 months, stimulation will consist in switching to burst for 1 month, and patients will choose which modality/waveform they receive and will then be reassessed at 6 and 12 months. In addition to our primary outcome based on pain rating, this study is designed to assess quality of life, functional disability, psychological distress, pain surface coverage, global impression of change, medication quantification, adverse events, brain functional imaging and electroencephalography, with the objective being to provide a multidimensional insight based on composite pain assessment.

Percutaneous Spinal Cord Stimulation Lead Placement Under Deep Sedation and General Anesthesia

INTRODUCTION

Spinal cord stimulation (SCS) is a commonly utilized therapy for the treatment of neuropathic pain conditions. The Neurostimulation Appropriateness Consensus Committee (NACC) has recommended that the placement of percutaneous SCS leads be performed in an awake patient capable of providing feedback. It is not currently known how commonly this recommendation is adhered to by physicians in clinical practice. This article presents the findings of a survey designed to answer this important question.

METHODS

We conducted a survey of the active membership of the American Society of Regional Anesthesia and Pain Medicine (ASRA) and the Spine Intervention Society (SIS) regarding practice patterns with SCS therapy. We analyzed the percent of respondents who indicated that they use deep sedation and general anesthesia during SCS placement as well as any reported complications.

RESULTS

Many practitioners frequently utilize deep sedation as well as general anesthesia when performing SCS implants. Our findings demonstrate that 77% of physicians reported that they utilize deep sedation for permanent SCS implants at times, and 45% of physicians reported the use of general anesthesia for 10 kHz implants. Additionally, 94% of physicians reported that they have never had a complication related to the use of general anesthesia for a spinal cord stimulator placement.

CONCLUSIONS

This survey provides initial data on SCS practices among a large cohort of clinicians who utilize SCS. SCS lead placement under deep sedation and general anesthesia appears to be common practice for many physicians who perform implants. This survey should stimulate further research on this topic, given that the current safety guidelines and the rate of physicians reporting the use of deep sedation and general anesthesia for spinal cord stimulator placement remain at odds.

Efficacy and Safety of 10 kHz Spinal Cord Stimulation Using Cervical and Thoracic Leads: A Single-Center Retrospective Experience

INTRODUCTION

Spinal cord stimulation (SCS) with lower thoracic leads has been studied extensively. However, the evidence base for cervical SCS is less well developed, and reports of multiarea SCS lead placement are uncommon. Therefore, this single-center retrospective study evaluated outcomes from 10-kHz SCS with cervical or combined cervical and thoracic lead placement.

METHOD

All patients that underwent a 10-kHz SCS trial with either cervical or combined cervical and thoracic lead placement between 2015 and 2020 were included in our study. We reviewed patient's charts for demographic information, lead placement, and pain scores up to 48 months after implantation.

RESULTS

Of the 105 patients that underwent a 10-kHz SCS trial during the review period, 92 (88%) had back/neck or extremity pain that responded to therapy (≥ 50% pain relief from baseline) and received a permanent system. Sixty-two of these patients (67%) were implanted with combined cervical and thoracic leads, while 30 (33%) received cervical-only leads. Pain relief in both regions exceeded 60% at most visits throughout the 48-month study period. Throughout follow-up, the responder rate in both pain areas was consistently ≥ 70%. No unexpected adverse events occurred.

CONCLUSION

The 10-kHz SCS provided effective and durable pain relief with either cervical or combined cervical and thoracic leads. The efficacy and safety profile of both applications appears to be comparable to lower thoracic SCS. Our results suggest that 10-kHz SCS is a useful paresthesia-free therapeutic option for chronic neuropathic pain originating in the cervical area, as well as more complex multiarea pain presentations.

Factors Contributing to Spinal Cord Stimulation Outcomes for Chronic Pain

OBJECTIVE

Spinal cord stimulation (SCS) has been shown to be a safe and effective therapy for patients with chronic pain. However, some patients do not obtain or maintain adequate pain relief after SCS. The goal of this study was to identify factors that affect patient outcome with regard to SCS.

MATERIALS AND METHODS

A retrospective analysis of electronic medical records at a single site was performed. Records for 181 patients who received SCS implants from 2014 through 2016 were collected with follow-up data captured up to August 2019. Patient outcome was measured by device explantation and patient benefit from the SCS. Study parameters included demographic characteristics, history of pain, SCS implant characteristics, and postimplantation events.

RESULTS

An earlier diagnosis of radiculopathy was associated with an increased risk of poor benefit (relative risk [RR], 1.81; 95% CI, 1.19-2.74; p = 0.008). Postimplantation falls were associated with an increased risk of poor benefit (RR, 2.17; 95% CI, 1.48-3.17; p = 0.009). Device manufacturer was associated with both patient benefit and explantation. Device 2 was associated with a reduced risk of poor benefit (RR, 0.52; 95% CI, 0.32-0.85; p = 0.009). Device 4 was associated with an increased risk of poor benefit (RR, 1.71; 95% CI, 1.14-2.55; p = 0.02) and increased risk of device explantation (RR, 2.69; 95% CI, 1.2-6.02; p = 0.03).

CONCLUSIONS

Patient outcome was associated with diagnosis, postimplantation falls, and device manufacturer. Further investigation is recommended to confirm associations through prospective studies that can more accurately quantify patient outcome over longer periods.

Difficult removal of exposed peripheral nerve stimulator leads: a report of 2 cases

Peripheral nerve stimulators serve as an alternative modality to treat chronic pain conditions; however, long-term complications, specifically lead migration, may occur.

Introduction:

Peripheral nerve stimulators have emerged as a new generation of advanced modalities to treat chronic pain and avoid opioids. They transmit electrical stimulation through implanted leads and wireless, wearable, external generators. Common complications include infection, nerve damage, and migration of stimulating leads. This article describes 2 cases of complications from lead migration.

Methods:

Case 1 describes a 61-year-old man with chronic groin pain who underwent an uncomplicated ultrasound-guided ilioinguinal peripheral nerve lead implantation. Case 2 describes a 54-year-old woman with left shoulder pain who underwent an uncomplicated ultrasound-guided percutaneous lead placement near the axillary nerve through a deltoid approach. Both peripheral nerve stimulators were confirmed with fluoroscopy, and each patient was followed up every 2 months for the following 2 years.

Results:

Both patients experienced lead migration to the skin resulting in erythema and need for lead removal. Initial unsuccessful removal by traction resulted in retained fragments and need for open surgical removal.

Discussion:

Neurologic complications of peripheral nerve stimulator implantation are rare, but device-associated complications, specifically lead migration, remain a source of long-term problems that can result in decreased coverage of the intended neural target.

Conclusion:

Thorough patient education, early postimplantation assessment, and extended routine follow-up are necessary to decrease lead-associated complications. If migration does occur, the potential impact of scar tissue on removal should be considered.

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

BACKGROUND

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

METHODS

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

RESULTS

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

CONCLUSIONS

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

Ultra-Low Energy Cycled Burst Spinal Cord Stimulation Yields Robust Outcomes in Pain, Function, and Affective Domains: A Subanalysis From Two Prospective, Multicenter, International Clinical Trials

INTRODUCTION

DeRidder's burst stimulation design has become a key spinal cord stimulation (SCS) waveform because it reduces the intensity of pain as well as its associated emotional distress. The brain pathways underlying these outcomes may also allow for the effects of stimulation to carry over after stimulation is turned off, making it amenable to intermittent application. Here, the utility of intermittently cycled burst was evaluated using data from two large real-world prospective studies (TRIUMPH, REALITY).

MATERIALS AND METHODS

Subjects used intermittent dosing in a 1:3 ratio (30 sec on, 90 sec off; N = 100) in TRIUMPH and 1:12 ratio in REALITY (30-sec on, 360-sec off; N = 95) for six months. Pain intensity (0-10 numeric rating scale), pain-related emotions on the pain catastrophizing scale (PCS), and physical function on PROMIS questionnaires were compared with preimplant baseline ratings and by group.

RESULTS

In both groups, mean pain intensity decreased by nearly 50% relative to baseline, PCS scores significantly decreased, and physical function improved. Importantly, no differences between the 1:3 and 1:12 groups were identified. A high proportion, 80% and 77% of the 1:3 and 1:12 groups, respectively, were considered responders on a multiple measures. No adverse events were associated with intermittent stimulation.

DISCUSSION

Intermittent cycling of burst SCS lowers the overall electric charge delivered to the spinal cord and preserves battery consumption, without compromising pain relief and associated symptoms.

Spinal Cord Stimulation: Viable Therapeutic Option for Postlaminectomy Syndrome in Elderly Patients

We present a 76-year-old man with chronic back pain refractory to treatment secondary to spinal trauma from a motor vehicle accident 34 years ago. After trauma, multiple interventions were performed due to spinal instability. The patient was diagnosed with the postlaminectomy syndrome. Multimodal analgesia management failed to control our patient’s pain, severely affecting our patient and his family’s quality of life. For these reasons, a spinal cord stimulator was implanted despite our patient age. After four months, our patient presented with significant improvement in his life quality.

Lead migration and fracture rate in dorsal root ganglion stimulation using anchoring and non-anchoring techniques: A multicenter pooled data analysis

INTRODUCTION

Dorsal root ganglion stimulation (DRG-S) is a neuromodulation technique introduced in the last decade with evolving implant methods. Initial prospective research found low incidences of lead migration and lead fracture with DRG-S. However, several recent studies have highlighted high lead migration and lead fracture rates with DRG-S. We investigated the influence of lead anchoring on migrations and fractures.

METHODS

We performed a retrospective review between 2016 and 2020 of individuals implanted with DRG-S leads by 4 experienced implanters. The implanters independently changed their standard practice regarding lead anchoring over time, with opposing trends (no anchoring > anchoring, anchoring > no anchoring). We compared lead migration and lead fracture rates between anchored and unanchored DRG-S leads in the entire study cohort. Cox regression was performed on lead migration and fracture distributions.

RESULTS

We included 756 leads (n = 565 anchored and n = 191 unanchored) from 249 patients. In unanchored leads, migration occurred in 16 leads (8.4%) from 13 patients (21.0%). In anchored leads, migration occurred in 8 leads (1.4%) from 5 patients (2.7%). Fracture in unanchored leads occurred in 6 leads (3.1%) from 6 patients (9.7%). Fractures in anchored leads occurred in 11 leads (1.9%) from 9 patients (4.8%). The migration survival distributions for the anchored and unanchored leads were statistically significantly different (p < 0.01) with decreased survival for unanchored leads (hazard ratio = 5.8, 95% confidence interval [CI] = 2.2-15.5).

DISCUSSION

We found that anchoring DRG-S leads significantly reduces lead migration when compared to leads placed without an anchor. There was no significant difference in fracture rate between anchored and unanchored leads.

Spinal cord stimulator for neuropathic pain in a patient with severe disability due to transverse myelitis

Transverse myelitis is an inflammatory disease of the central nervous system that disrupts nerve signals' conduction. The illness is characterised by weakness in the lower limbs accompanied by paresthesia and urinary and bowel incontinence. The most disabling sequel is the onset of chronic neuropathic pain, which can severely limit the patient's independence and negatively affect her quality of life. We present the case of a patient who received a spinal neurostimulator after a failure of conventional medical treatment. Masking pain through paresthesia, a mechanism provided by the device significantly reduces pain perception. The treatment success in our patient represents an advance in pain therapy.

The Effectiveness of Dorsal Root Ganglion Neurostimulation for the Treatment of Chronic Pelvic Pain and Chronic Neuropathic Pain of the Lower Extremity: A Comprehensive Review of the Published Data

OBJECTIVE

To evaluate the effectiveness of dorsal root ganglion neurostimulation for the treatment of refractory, focal pain in the pelvis and lower extremities.

DESIGN

Systematic review.

OUTCOME MEASURES

The primary outcome was ≥50% pain relief. Secondary outcomes were physical function, mood, quality of life, opioid usage, and complications.

RESULTS

One pragmatic randomized controlled trial, four prospective cohort studies, and eight case series met the inclusion criteria. A worst-case scenario analysis from the randomized controlled trial reported ≥50% pain relief in 74% of patients with dorsal root ganglion neurostimulation vs. 51% of patients who experienced at least 50% relief with spinal cord stimulation at 3 months. Cohort data success rates ranged from 43% to 83% at ≤6 months and 27% to 100% at >6 months. Significant improvements were also reported in the secondary outcomes assessed, including mood, quality of life, opioid usage, and health care utilization, though a lack of available quantitative data limits further statistical analysis. Complication rates vary, though the only randomized controlled trial reported a higher rate of adverse events than that seen with traditional neurostimulation.

CONCLUSIONS

In accordance with the Grades of Recommendation, Assessment, Development, and Evaluation system, low-quality evidence supports dorsal root ganglion neurostimulation as a more effective treatment than traditional neurostimulation for pain and dysfunction associated with complex regional pain syndrome or causalgia. Very low-quality evidence supports dorsal root ganglion neurostimulation for the treatment of chronic pelvic pain, chronic neuropathic groin pain, phantom limb pain, chronic neuropathic pain of the trunk and/or limbs, and diabetic neuropathy.

Neuromodulation in the treatment of postoperative epidural fibrosis: comparison of the extent of epidural fibrosis and the effect of stimulation

The goal was to prove that when a cohort of patients is chosen precisely, dorsal column stimulation provides significant improvement to quality of life. We studied a cohort of 50 patients with the history of failed back surgery syndrome coupled with epidural fibrosis (EF). A percutaneous implantation technique was used in each of the 50 patients. The study group was composed of 20 women and 28 men aged 26-67 years (mean age 49). A prospective observational questionnaire-based study was used. According to the methods, Ross's classification was adjusted to four degrees of scar size for our study objective. Despite this adjustment, it was not possible to statistically evaluate our research, due to very similar results in Groups I, III and IV. Patients without epidural fibrosis were assigned to Group 0, and patients with EF of different ranges were assigned to Group 1. The mean change in visual analogue scale DeltaVAS after our division into Group 0 was 4.82; for Group 1 it was 6.13. Evaluation of EF and DeltaVAS correlation by paired t-test shows a statistically higher effect of spinal cord stimulation (SCS) in the epidural fibrosis group, compared to group 0 without postoperative epidural fibrosis (p=0.008). The extent of epidural fibrosis is an important factor for Failed back surgery syndrome (FBSS). FBSS is the basis for the existence of neuropathic pain after lumbar spinal surgery. There is clear evidence of a correlation between patients with epidural scar formation on MR scan and the effect of dorsal column stimulation.

Anesthetic considerations in patients with implantable devices and chronic pain surgery

The use of advanced invasive techniques for the control of chronic pain in patients with multiple comorbidities is becoming increasingly common. Neuromodulation offers a new management alternative involving the infusion of one or more drugs into the epidural or intrathecal space through a fully implantable infusion pump. It also involves spinal stimulation, a minimally invasive technique in which electrodes are positioned in the epidural space and connected to a pulse generator that is implanted subcutaneously and generates pulses designed to suppress the noxious stimulus. This article will describe the anesthetic considerations in cases of implantable drug delivery systems, and spinal and peripheral nerve stimulation devices. Additionally, patients with electrical or drug neuromodulation devices may present to anesthetic practice for surgical indications unrelated to their chronic pain pathology. Hence the importance of being familiar with the basic components of these devices, how they work, what drugs they use and the potential associated complications in the perioperative context, in order to ensure proper management and patient safety.

Wireless and battery-free platforms for collection of biosignals

Recent progress in biosensors have quantitively expanded current capabilities in exploratory research tools, diagnostics and therapeutics. This rapid pace in sensor development has been accentuated by vast improvements in data analysis methods in the form of machine learning and artificial intelligence that, together, promise fantastic opportunities in chronic sensing of biosignals to enable preventative screening, automated diagnosis, and tools for personalized treatment strategies. At the same time, the importance of widely accessible personal monitoring has become evident by recent events such as the COVID-19 pandemic. Progress in fully integrated and chronic sensing solutions is therefore increasingly important. Chronic operation, however, is not truly possible with tethered approaches or bulky, battery-powered systems that require frequent user interaction. A solution for this integration challenge is offered by wireless and battery-free platforms that enable continuous collection of biosignals. This review summarizes current approaches to realize such device architectures and discusses their building blocks. Specifically, power supplies, wireless communication methods and compatible sensing modalities in the context of most prevalent implementations in target organ systems. Additionally, we highlight examples of current embodiments that quantitively expand sensing capabilities because of their use of wireless and battery-free architectures.

Percutaneous Peripheral Nerve Stimulation of the Medial Branch Nerves for the Treatment of Chronic Axial Back Pain in Patients After Radiofrequency Ablation

OBJECTIVE

Lumbar radiofrequency ablation is a commonly used intervention for chronic back pain. However, the pain typically returns, and though retreatment may be successful, the procedure involves destruction of the medial branch nerves, which denervates the multifidus. Repeated procedures typically have diminishing returns, which can lead to opioid use, surgery, or implantation of permanent neuromodulation systems. The objective of this report is to demonstrate the potential use of percutaneous peripheral nerve stimulation (PNS) as a minimally invasive, nondestructive, motor-sparing alternative to repeat radiofrequency ablation and more invasive surgical procedures.

DESIGN

Prospective, multicenter trial.

METHODS

Individuals with a return of chronic axial pain after radiofrequency ablation underwent implantation of percutaneous PNS leads targeting the medial branch nerves. Stimulation was delivered for up to 60 days, after which the leads were removed. Participants were followed up to 5 months after the start of PNS. Outcomes included pain intensity, disability, and pain interference.

RESULTS

Highly clinically significant (≥50%) reductions in average pain intensity were reported by a majority of participants (67%, n = 10/15) after 2 months with PNS, and a majority experienced clinically significant improvements in functional outcomes, as measured by disability (87%, n = 13/15) and pain interference (80%, n = 12/15). Five months after PNS, 93% (n = 14/15) reported clinically meaningful improvement in one or more outcome measures, and a majority experienced clinically meaningful improvements in all three outcomes (i.e., pain intensity, disability, and pain interference).

CONCLUSIONS

Percutaneous PNS has the potential to shift the pain management paradigm by providing an effective, nondestructive, motor-sparing neuromodulation treatment.

Spinal cord stimulation in the treatment of peripheral vascular disease: a systematic review - revival of a promising therapeutic option?

INTRODUCTION

Peripheral vascular disease (PVD) is caused by a blood circulation disorder of the arteries and Critical Limb Ischemia (CLI) is the advanced state of PVD. For patients with surgically non-reconstructable CLI, Spinal Cord Stimulation (SCS) appears to be an alternative therapeutic option.

OBJECTIVE

The aim of our study was to investigate the efficacy of SCS in non-reconstructable CLI compared with the conservative treatment and re-appraise the existing literature in light of the recent advances in neuromodulation.

METHODS

We conducted a systematic review based on the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines, using electronic databases and reference lists for article retrieval.

RESULTS

A total of 404 records were identified and finally 6 randomised controlled trials (RCTs), a Cochrane review and a meta-analysis were included in our systematic review. The studies assessed the efficacy of tonic SCS in the treatment of patients with non-reconstructable CLI compared with the conservative treatment. There is moderate to high quality evidence suggesting, that tonic SCS has beneficial effects for patients suffering from non-reconstructable CLI in terms of limb salvage, pain relief, clinical improvement and quality of life. The contradictory conclusions of the two meta-analyses regarding the efficacy of SCS for limb salvage at 12 months refer rather to the magnitude of the beneficial effect than to the effect itself. So far, the current literature provides evidence about the traditional tonic SCS but there is a lack of studies investigating the efficacy of new waveforms in the treatment of non-reconstructable CLI.

CONCLUSION

SCS represents an alternative for PVD patients with non-reconstructable CLI and the existing literature provides encouraging clinical results, that should not be neglected. Instead, they should be re-appraised in light of the recent advances in neuromodulation with the emergence of novel waveform technologies and neuromodulation targets.

Efficacy and Safety of 10 kHz Spinal Cord Stimulation for the Treatment of Chronic Pain: A Systematic Review and Narrative Synthesis of Real-World Retrospective Studies

10 kHz spinal cord stimulation (SCS) is increasingly utilized globally to treat chronic pain syndromes. Real-world evidence complementing randomized controlled trials supporting its use, has accumulated over the last decade. This systematic review aims to summarize the retrospective literature with reference to the efficacy and safety of 10 kHz SCS. We performed a systematic literature search of PubMed between 1 January 2009 and 21 August 2020 for English-language retrospective studies of ≥3 human subjects implanted with a Senza® 10 kHz SCS system and followed-up for ≥3 months. Two independent reviewers screened titles/abstracts of 327 studies and 46 full-text manuscripts. In total, 16 articles were eligible for inclusion; 15 reported effectiveness outcomes and 11 presented safety outcomes. Follow-up duration ranged from 6-34 months. Mean pain relief was >50% in most studies, regardless of follow-up duration. Responder rates ranged from 67-100% at ≤12 months follow-up, and from 46-76% thereafter. 32-71% of patients decreased opioid or nonopioid analgesia intake. Complication incidence rates were consistent with other published SCS literature. Findings suggest 10 kHz SCS provides safe and durable pain relief in pragmatic populations of chronic pain patients. Furthermore, it may decrease opioid requirements, highlighting the key role 10 kHz SCS can play in the medium-term management of chronic pain.

A Retrospective Review of Lead Migration Rate in Patients Permanently Implanted with Percutaneous Leads and a 10 kHz SCS Device

Background

Spinal cord stimulation (SCS) has been used over decades for pain management, but migration of percutaneous leads has been the most common complication. Better surgical techniques and newer SCS technologies likely reduced the incidence of lead migration requiring surgical revision, although data are sparse. This study aimed to retrospectively evaluate the incidence of clinically significant percutaneous lead migration in patients permanently implanted with a 10 kHz SCS system.

Methods

Consecutive patients with chronic trunk and/or limb pain, permanently implanted between January 2016 and June 2019, were included in the analysis. Data were collected from the hospital's electronic medical records and the manufacturer's database. Clinically significant lead migration, defined as diminished pain relief followed by surgery to correct lead location, was assessed at the 6-month follow-up.

Results

At the 6-month follow-up, there were no cases of clinically significant lead migration, average pain relief was 65.2%, 82% of patients had response (≥50% pain relief), improvement of function was noted in 72% of patients, and decrease of medication was observed in 42% of patients. Therapy efficacy was sustained in patients with >12 months follow-up; the average pain relief was 58.5%, and the response rate was 82%.

Conclusions

The surgical techniques in use today are designed to minimise the risk of percutaneous lead migration and may have reduced its incidence. In addition, new SCS systems may give greater opportunity to mitigate cases of minor lead movement using alternative stimulation programs.

Unexpected extrusion of the implantable pulse generator of the spinal cord stimulator - A case report

Background

Despite significant technological advances in the implantable pulse generator (IPG), complications can still occur. We report a case that unexpected extrusion of the IPG of spinal cord stimulation (SCS) was promptly identified and successfully removed without any complications.

Case

After a car accident 4 years ago, a 55-year-old male who was diagnosed with complex local pain syndrome in his right leg. The SCS was inserted with 2 leads, with the IPG being implanted in the right lower abdomen region. Four years later, he developed extrusion of the IPG from his abdominal region. This unexpected extrusion may have been related to pressure necrosis caused by continued compression of pocket site where a belt was frequently tied. The IPG and the leads were successfully removed without infection occurring.

Conclusions

To prevent unexpected extrusion of IPG, it is necessary to consider in advance whether the pocket site is pressed against the belt.

Allergy Considerations in Implanted Neuromodulation Devices

OBJECTIVES

Allergic reactions are rare and poorly understood complications of neuromodulation device implantation. There are currently no guidelines for management of allergic reactions to these devices and their components. Here we review the published cases of allergic reactions to implanted neuromodulatory devices and leverage the experiences of other specialties that deal with similar complications to formulate recommendations for prevention and management.

MATERIALS AND METHODS

A review and assessment of the literature.

RESULTS

Allergic reactions to a number of implantable devices have been observed and published. In dentistry and orthopedics, metals such as nickel are the most frequent cause of allergic reactions. In interventional cardiology, where devices closely resemble neuromodulatory devices, titanium, silicone, and polyurethanes are the most common causes of allergic reactions. In neurosurgery, allergic reactions to implantable neuromodulatory devices are rare, and we summarize 13 cases published to date. Such allergic reactions generally present as local dermatitis, erythema, and pruritus, which can be difficult to distinguish from surgical site infection. In one published case, symptoms resolved with corticosteroid treatment, but all other cases required explantation. The successful reimplantation with a modified device was reported in some cases.

CONCLUSIONS

Patients should be screened for a personal history of contact allergy before implantation procedures. A multidisciplinary approach to suspected cases of postoperative allergic reactions involving collaboration between neurosurgeons and other implanting physicians, dermatologists or allergists, and device manufacturers is recommended. In cases where an allergic reaction is suspected, an infectious etiology should be ruled out first. Clinical suspicion can then be supported with the use of patch testing, interpreted by an experienced dermatologist or allergist. If patch testing supports an allergic etiology, the implanting physician and the device manufacturer can work together to modify the device for safe reimplantation.

Factors Associated With Implantable Pulse Generator Site Pain: A Multicenter Cross-Sectional Study

OBJECTIVES

Implantable pulse generator (IPG) site pain following neuromodulation procedures is a recognized complication. The site of the IPG placement varies depending on the neuromodulation type and physician preference. The incidence of IPG site pain as a function of the site of IPG implantation has not been studied systematically.

MATERIALS AND METHODS

We performed a multicenter cross-sectional survey of the incidence, severity, and quality of IPG site pain, location of the IPG, the pain management needs, functional impairment, and cosmetic appearance related to the IPG placement. Contingency table analysis was conducted for categorical variables, and logistic regression analysis and linear regression model was used.

RESULTS

The survey response rate was 60.5% (n = 510). Overall, 31.0% of patients reported pain at the IPG site in the last 72 hours with 31.4% reporting moderate to severe pain and 7.6% reporting severe pain. Older age was inversely associated with IPG-related pain (OR = 0.97, 95% CI = 0.96-0.99, p = 0.001). IPG implantation site did not have a statistically significant interaction with IPG site pain (p > 0.05). The most important factor for IPG site-associated pain was having a spinal cord stimulator implanted as compared to a deep brain stimulator, or sacral nerve stimulator. Most subjects reported no functional impairment related to IPG site pain (91%), found the IPG site pain as expected (80%), and found IPG site cosmetic appearance as expected (96%).

CONCLUSIONS

The incidence of IPG site pain is an important complication of invasive neuromodulation. The anatomic location of the IPG placement does not appear to affect the incidence or severity of IPG site pain. However, the presence of a pre-implant chronic pain disorder does appear to affect the frequency and severity of IPG site pain.

Failure of SCS MR-Conditional Modes Due to High Impedance: A Review of Literature and Case Series

Introduction

Magnetic resonance imaging (MRI) conditional modes are a novel feature for certain Food and Drug Administration (FDA)-approved spinal cord stimulation (SCS) devices. However, there is a paucity of literature around the limitation of MRI-conditional modes (“MRI safe”), specifically in clinical scenarios where urgent MRIs may be needed. One such limitation is load impedance, referring to the circuit’s resistance to the current being generated by the system. High impedance can limit the MRI-conditional mode capability, presenting potential harm to a patient undergoing an MRI or make an MRI unable to be completed.

Methods

Three cases were identified, and informed consent was obtained. All information was obtained via retrospective chart review.

Results

In this case series of three patients where MRI-conditional SCS systems were unable to be placed in “MRI safe” settings, preventing timely MRI study completion in the setting of high impedance, all three were required to undergo alternative imaging including CT scans, and two patients ultimately had the system explanted and one chose to be re-implanted after completion of scans.

Conclusion

This case series highlights the need for further investigation of impedance in SCS systems and potential limitations for future MRI usage. The review of literature of impedance in SCS shows both device- and physiologic-related etiologies for changes in impedance that warrant consideration by the implanting physician.

Psychosocial characteristics of candidates for implantable pain devices: validation of an assessment model

Aim: To provide a detailed profile of Veteran and community patients with chronic pain who completed preprocedural psychological evaluations for implantable pain devices. Patients & methods: A total of 157 candidates completed a preimplantable pain device evaluation between June 2018 and October 2019 with a pain psychologist that included a structured interview, elicitation of patient-centered goals for the implantable device, and psychometric testing. Results: Candidates demonstrated moderate to high rates of sleep impairment (73%), depressive symptoms (62%), anxiety symptoms (61%), pain catastrophizing (37%), cognitive impairment screen (30%) and somatic symptoms (24%). Conclusion: Candidates for implantable pain devices report high rates of mood, sleep and cognitive impairment, reinforcing the value of preprocedural psychological evaluations.

Neuromodulation Management of Chronic Neuropathic Pain in The Central Nervous system

Neuromodulation is becoming one of the clinical tools for treating chronic neuropathic pain by transmitting controlled physical energy to the pre-identified neural targets in the central nervous system. Its nature of drug-free, non-addictive and improved targeting have attracted increasing attention among neuroscience research and clinical practices. This article provides a brief overview of the neuropathic pain and pharmacological routines for treatment, summarizes both the invasive and non-invasive neuromodulation modalities for pain management, and highlights an emerging brain stimulation technology, transcranial focused ultrasound (tFUS) with a focus on ultrasound transducer devices and the achieved neuromodulation effects and applications on pain management. Practical considerations of spatial guidance for tFUS are discussed for clinical applications. The safety of transcranial ultrasound neuromodulation and its future prospectives on pain management are also discussed.

Spinal cord stimulation in the management of neuropathic pain in cancer patients: case report

Introduction: Neuropathic pain is present in up to 40 % of all cancer patients. A considerable number of patients fail to achieve enough pain relief with conventional treatment, which is why therapeutic alternatives such as spinal cord stimulation should be considered. Case description and results: This is the case of a female patient with chronic neuropathic pain secondary to a partial femoral nerve injury sustained during resection and lymph node dissection surgery with curative intent for a large stage II cell squamous cell carcinoma T2N0M0, localized in the right popliteal fossa. The patient presented with difficult to manage chronic neuropathic pain, despite receiving multiple oral analgesics and nerve blocks. A medullary neurostimulator was implanted that relieved the patient’s pain intensity in up to 80%, in addition to improved function and quality of life. Conclusions: spinal cord stimulation is considered an effective neuromodulatory intervention which has shown satisfactory results in the treatment of various types of refractory chronic pain in cancer patients, including neuropathic pain.

BurstDR spinal cord stimulation in the treatment of chronic visceral pain

Background:Visceral pain can be disabling for patients and challenging to treat in the clinic. Spinal cord stimulation is a NICE approved treatment for chronic neuropathic pain, presenting potential advantages over conventional therapies for managing chronic visceral pain. Results: A retrospective study revealed that a specific type of spinal cord stimulation, BurstDR^TM (Abbott, TX, USA), was effective at improving pain and quality of life in patients with chronic visceral pain. Baseline pain scores significantly correlated with change at follow-up, suggesting it may be possible to identify potential responders from the outset. BurstDR was safe: rates of revision, explantation and complications were low. Conclusion: Clinical trials exploring the long-term effects of BurstDR including a control arm are needed. Findings could have the potential to inform best practice and improve outcomes for individuals with chronic visceral pain.

10 kHz spinal cord stimulation for the treatment of chronic back and/or leg pain: Summary of clinical studies

Chronic pain has a major impact on sufferers and their families. The associated health care costs are substantial. In the context of increasing prevalence, effective treatment options are ever more important. 10 kHz spinal cord stimulation has been shown to effectively provide pain relief, aid in opioid reduction, and improve quality of life in patients with chronic intractable pain. The present review aims to summarize the clinical evidence related to the use of 10 kHz SCS in chronic back and/or leg pain. We searched the PubMed database between 2009 and 2 June 2020 for articles reporting clinical studies that included at least 10 human subjects permanently treated with a 10 kHz SCS system (Senza^® system) for chronic back and/or leg pain for a minimum of 3 months. A randomized controlled trial (SENZA-RCT), as well as several prospective and retrospective studies, reported clinical outcomes in subjects with chronic back and leg pain treated with 10 kHz SCS. A high proportion of subjects (60%–80%) reported long-term response to therapy. Pain relief was provided without paresthesia. Other studies showed promising pain relief outcomes in subjects with back pain ineligible for spinal surgery, neuropathic limb pain, and in those with previously failed traditional low-frequency SCS. Most studies reported improved quality of life metrics and/or reduced opioid intake. Level 1 evidence has already been established for the use of 10 kHz SCS in treating chronic back and leg pain, corroborated by real-world, clinical experience. Exploratory studies also show the potential of the therapy in other refractory pain syndromes, although larger studies are desired to validate their findings. Overall, the literature suggests that 10 kHz SCS provides long-term pain relief in a high proportion of patients, along with improved quality of life and reduced opioid consumption.

Neuromodulation and the Epidemiology of Magnetic Resonance Utilization for Lung, Breast, Colon, and Prostate Cancer

BACKGROUND

Neuromodulation is a growing therapeutic modality for the treatment of chronic pain. Determining whether a patient is an appropriate candidate for implantation of a neuromodulatory device and whether the device requires an MRI conditional feature necessitates understanding the patient's likelihood of requiring an MRI. Active treatment of cancer represents known high-risk clinical scenarios for MRI. However, the growth of MRI as a tool for diagnosis of cancer also warrants consideration by implanting physicians when assessing high-risk patients.

MATERIALS AND METHODS

Here, we conduct a systematic review of the literature to determine the epidemiology for MR utilization for breast, lung, prostate, and colon cancer. Out of 126 papers reviewed, 39 were ultimately analyzed to determine the relative likelihood of an MRI in the course of oncologic care.

RESULTS

We find that there is a low likelihood for MRI to be utilized as part of any screening process and a variable likelihood during the staging and surveillance phases across all cancer subtypes depending on the clinical circumstances. Certain populations present special consideration for MRI screening, such as the high at-risk breast cancer population, and MRI surveillance and staging, such as aging males (>50 years old) at risk for prostate cancer or individuals diagnosed with rectal cancers.

CONCLUSION

High likelihood of MRI within the oncologic context represents important distinction criteria for neuromodulation as patients may benefit from implantation of an MR conditional system.

Sensory restoration by epidural stimulation of the lateral spinal cord in upper-limb amputees

Restoring somatosensory feedback to people with limb amputations is crucial to improve prosthetic control. Multiple studies have demonstrated that peripheral nerve stimulation and targeted reinnervation can provide somatotopically relevant sensory feedback. While effective, the surgical procedures required for these techniques remain a major barrier to translatability. Here, we demonstrate in four people with upper-limb amputation that epidural spinal cord stimulation (SCS), a common clinical technique to treat pain, evoked somatosensory percepts that were perceived as emanating from the missing arm and hand. Over up to 29 days, stimulation evoked sensory percepts in consistent locations in the missing hand regardless of time since amputation or level of amputation. Evoked sensations were occasionally described as naturalistic (e.g. touch or pressure), but were often paresthesias. Increasing stimulus amplitude increased the perceived intensity linearly, without increasing area of the sensations. These results demonstrate the potential of SCS as a tool to restore somatosensation after amputations.

Even some of the most advanced prosthetic arms lack an important feature: the ability to relay information about touch or pressure to the wearer. In fact, many people prefer to use simpler prostheses whose cables and harnesses pass on information about tension. However, recent studies suggest that electrical stimulation might give prosthesis users more sensation and better control.

After an amputation, the nerves that used to deliver sensory information from the hand still exist above the injury. Stimulating these nerves can help to recreate sensations in the missing limb and improve the control of the prosthesis. Still, this stimulation requires complicated surgical interventions to implant electrodes in or around the nerves. Spinal cord stimulation – a technique where a small electrical device is inserted near the spinal cord to stimulate nerves – may be an easier alternative. This approach only requires a simple outpatient procedure, and it is routinely used to treat chronic pain conditions.

Now, Chandrasekaran, Nanivadekar et al. show that spinal cord stimulation can produce the feeling of sensations in a person’s missing hand or arm. In the experiments, four people who had an arm amputation underwent spinal cord stimulation over 29 days. During the stimulation, the participants reported feeling electrical buzzing, vibration, or pressure in their missing limb. Changing the strength of the electric signals delivered to the spinal cord altered the intensity of these sensations.

The experiments are a step toward developing better prosthetics that restore some sensation. Further studies are now needed to determine whether spinal cord stimulation would allow people to perform sensory tasks with a prosthetic, for example handling an object that they cannot see.

Treatment of a Large Cohort of Veterans Experiencing Musculoskeletal Disorders with Spinal Cord Stimulation in the Veterans Health Administration: Veteran Characteristics and Outcomes

OBJECTIVE

Spinal cord stimulator (SCS) implantation is used to treat chronic pain, including painful musculoskeletal disorders (MSDs). This study examined the characteristics and outcomes of veterans receiving SCSs in Veterans Health Administration (VHA) facilities.

METHODS

The sample was drawn from the MSD Cohort and limited to three MSDs with the highest number of implants (N=815,475). There were 1490 veterans with these conditions who received SCS implants from 2000 to 2012, of which 95% (n=1414) had pain intensity numeric rating scale (NRS) data both pre- and post-implant.

RESULTS

Veterans who were 35-44 years old, White, and married reported higher pain NRS ratings, had comorbid inclusion diagnoses, had no medical comorbidities, had a BMI 25-29.9, or had a depressive disorder diagnosis were more likely to receive an SCS. Veterans 55+ years old or with an alcohol or substance use disorder were less likely to receive an SCS. Over 90% of those receiving an SCS were prescribed opioids in the year prior to implant. Veterans who had a presurgical pain score ≥4 had a clinically meaningful decrease in their pain score in the year following their 90-day recovery period (Day 91-456) greater than expected by chance alone. Similarly, there was a significant decrease in the percent of veterans receiving opioid therapy (92.4% vs 86.6%, p<0.0001) and a significant overall decrease in opioid dose [morphine equivalent dose per day (MEDD) =26.48 vs MEDD=22.59, p<0.0003].

CONCLUSION

Results offer evidence of benefit for some veterans with the examined conditions. Given known risks of opioid therapy, the reduction is an important potential benefit of SCS implants.

The utilization of buprenorphine in chronic pain

Reclassification of chronic pain as a disease may be helpful because patients with chronic pain require significant treatment and rehabilitation with a clear diagnosis. This can help address critical factors including suffering, quality of life, participation, and with family and social life, which continue to become more important in evaluating the quality of the health care we give our patients today. During the past decade of the opioid epidemic, methadone was the primary treatment for opioid addiction until buprenorphine was approved. Buprenorphine's high-affinity partial agonist properties make it a good alternative to methadone due to lower abuse potential and safer adverse effect profile while maintaining significant efficacy. Expanded out-patient prescribing options have allowed physician and physician extenders such as physician assistants and nurse practitioners to treat these patients that otherwise would have been required to utilize methadone. With unique pharmacological properties, buprenorphine is a safe and effective analgesic for chronic pain. The literature for buprenorphine shows great potential for its utilization in the treatment of chronic pain.

Use of cannabidiol (CBD) for the treatment of chronic pain

Chronic pain can be recurrent or constant pain that lasts for longer than 3 months and can result in disability, suffering, and a physical disturbance. Related to the complex nature of chronic pain, treatments have a pharmacological and non-pharmacological approach. Due to the opioid epidemic, alternative therapies have been introduced, and components of the plant Cannabis Sativa, Δ9-tetrahydrocannabinol (THC) and cannabidiol (CBD) have gained recent interest as a choice of treatment. The exact mechanism for CBD is currently unknown, but unlike the CBD's psychoactive counterpart, THC, the side effects of CBD itself have been shown to be overall much more benign. The current pharmaceutical products for the treatment of chronic pain are known as nabiximols, and they contain a ratio of THC combined with CBD, which has been promising. This review focuses on the treatment efficacy of CBD, THC: CBD-based treatments for chronic pain and adverse events with each.

The Evolving Role of High-Frequency Spinal Cord Stimulation as Salvage Therapy in Neurostimulation

BACKGROUND

High-frequency 10-kHz spinal cord stimulation (10-kHz SCS) has shown promise in multicenter prospective trials for the management of chronic back and leg pain. Traditional spinal cord stimulation (t-SCS) has a long history of effectiveness in chronic neuropathic syndromes but not uncommonly can fail to provide long-term relief, leaving a significant group of patients with unsatisfactory outcomes. There is mounting evidence that 10-kHz SCS may offer relief in this subset of patients.

METHODS

The purpose of this retrospective analysis was to report a single-institution long-term experience of 10-kHz SCS in patients who did not get adequate pain relief with prior t-SCS devices. A temporary trial of 10-kHz SCS was carried out for 7 days, and those experiencing an average of 50% reduction in pain intensity underwent implantation. Patients were classified as moderate responders if relief was 31% to 50% and excellent responders if pain relief exceeded 50%.

RESULTS

Thirty-one patients who had experienced failed t-SCS primarily from poor paresthesia coverage underwent a trial of 10-kHz SCS and 29 underwent implantation. Twenty-eight patients were available for analysis, with 57.1% experiencing 30% response and 46.4% experiencing excellent response at a median follow-up of 21.2 (±8.4) months.

CONCLUSIONS

This small single-institution study suggests that a significant proportion of patients with previously failed t-SCS may achieve clinically meaningful and durable pain relief with 10-kHz SCS.