Spinal cord stimulation for complex regional pain syndrome: A systematic review of the clinical and cost-effectiveness literature and assessment of prognostic factors

Cervical Spinal Cord Stimulation for Failed Neck Surgery Syndrome

PURPOSE OF REVIEW

Cervical spine pain with or without radicular symptoms is a common condition leading to high utilization of the healthcare system with over 10 million medical visits per year. Many patients undergo surgical interventions and unfortunately are still left with neck and upper extremity pain, sometimes referred to as "Failed Neck Surgery Syndrome." When these options fail, cervical spinal cord stimulation can be a useful tool to decrease pain and suffering as well as reduce prescription medication use.

RECENT FINDINGS

Spinal cord stimulation is a well-established therapy for chronic back and leg pain and is becoming more popular for neck and upper extremity pain. Recent studies have explored cervical spinal cord stimulation with successful outcomes regarding improved pain scores, functional outcomes, and reduction of prescription medication use. Continued research into cervical spinal cord stimulation is essential for maximizing its therapeutic potential for patients with chronic neck and upper extremity pain. This review highlights the importance of cervical spinal cord stimulation as an option for patients with failed neck surgery syndrome.

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

BACKGROUND

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

METHODS

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

RESULTS

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

CONCLUSIONS

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

Methodological and statistical characteristics of meta-analyses on spinal cord stimulation for chronic pain: a systematic review

BACKGROUND

A growing number of meta-analyses (MA) have investigated the use of spinal cord stimulation (SCS) as a treatment modality for chronic pain. The quality of these MAs has not been assessed by validated appraisal tools.

OBJECTIVE

To examine the methodological characteristics and quality of MAs related to the use of SCS for chronic pain syndromes.

EVIDENCE REVIEW

An online literature search was conducted in Ovid MEDLINE(R), Ovid EMBASE, Ovid Cochrane Database of Systematic Reviews, and Scopus databases (January 1, 2000 through June 30, 2023) to identify MAs that investigated changes in pain intensity, opioid consumption, and/or physical function after SCS for the treatment of chronic pain. MA quality was assessed using A Measurement Tool to Assess Systematic Reviews (AMSTAR-2) critical appraisal tool.

FINDINGS

Twenty-five MAs were appraised in the final analysis. Three were considered "high" quality, three "low" quality, and 19 "critically low" quality, per the AMSTAR-2 criteria. There was no association between the publication year and AMSTAR-2 overall quality (β 0.043; 95% CI -0.008 to 0.095; p=0.097). There was an association between the impact factor and AMSTAR-2 overall quality (β 0.108; 95% CI 0.044 to 0.172; p=0.002), such that studies published in journals with higher impact factors were associated with higher overall quality. There was no association between the effect size and AMSTAR-2 overall quality (β -0.168; 95% CI -0.518 to 0.183; p=0.320).According to our power analysis, three studies were adequately powered (>80%) to reject the null hypothesis, while the remaining studies were underpowered (<80%).

CONCLUSIONS

The study demonstrates a critically low AMSTAR-2 quality for most MAs published on the use of SCS for treating chronic pain. Future MAs should improve study quality by implementing the AMSTAR-2 checklist items.

PROSPERO REGISTRATION NUMBER

CRD42023431155.

Spinal Nerve Root Stimulation for Chronic Pain: A Systematic Review

OBJECTIVE

Spinal cord stimulation (SCS) has been used as a minimally invasive and effective treatment modality for various chronic pain disorders, with the main target being stimulation of the dorsal columns; however, certain neuropathic pain areas involve dermatomes that are suboptimally covered by SCS. Stimulation of the spinal nerve roots has the advantage of targeting one or several dermatomes at the same time. The aim of this systematic review is to investigate the efficacy of spinal nerve root stimulation (SNRS) for chronic pain disorders.

MATERIALS AND METHODS

A detailed literature review was performed through the Ovid Embase and MEDLINE data bases in addition to reference searching. Gray literature was included by searching through common search engines using a simplified search strategy. Studies included were focused on adult patients (aged >18 years), diagnosis of chronic pain syndrome (including but not limited to complex regional pain syndrome, persistent spinal pain syndrome, neuropathic pain secondary to trauma or infection, postherpetic pain, and cancer pain). Patients must have undergone SNRS insertion, with ≥six months of documented pain intensity scores on follow-up.

RESULTS

A total of 40 studies underwent full text review, and 13 articles were included in final analysis. Mean preoperative pain intensity was 8.14 ± 0.74 on the visual analog scale, whereas mean postoperative pain intensity at one year was 3.18 ± 1.44. Of 119 patients, 83 (70%) achieved ≥50% reduction in pain intensity after SNRS, whereas 36 (30%) achieved <50% reduction in pain intensity. Only three studies assessed changes in analgesia medication dose and reported morphine equivalent doses varied by case series. Overall, there was a trend toward a reduction in analgesia medications in the postoperative period.

CONCLUSIONS

SNRS led to a mean 44% reduction in pain intensity, with a low level of certainty. In addition, there is some evidence to suggest that using SNRS is associated with reduced use of analgesics, including morphine and gabapentin.

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

STUDY DESIGN

This is a retrospective, observational study.

INTRODUCTION

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

MATERIALS AND METHODS

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

RESULTS

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

CONCLUSIONS

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

Objective wearable measures correlate with self-reported chronic pain levels in people with spinal cord stimulation systems

Spinal Cord Stimulation (SCS) is a well-established therapy for treating chronic pain. However, perceived treatment response to SCS therapy may vary among people with chronic pain due to diverse needs and backgrounds. Patient Reported Outcomes (PROs) from standard survey questions do not provide the full picture of what has happened to a patient since their last visit, and digital PROs require patients to visit an app or otherwise regularly engage with software. This study aims to assess the feasibility of using digital biomarkers collected from wearables during SCS treatment to predict pain and PRO outcomes. Twenty participants with chronic pain were recruited and implanted with SCS. During the six months of the study, activity and physiological metrics were collected and data from 15 participants was used to develop a machine learning pipeline to objectively predict pain levels and categories of PRO measures. The model reached an accuracy of 0.768 ± 0.012 in predicting the pain intensity of mild, moderate, and severe. Feature importance analysis showed that digital biomarkers from the smartwatch such as heart rate, heart rate variability, step count, and stand time can contribute to modeling different aspects of pain. The results of the study suggest that wearable biomarkers can be used to predict therapy outcomes in people with chronic pain, enabling continuous, real-time monitoring of patients during the use of implanted therapies.

Objective wearable measures and subjective questionnaires for predicting response to neurostimulation in people with chronic pain

BACKGROUND

Neurostimulation is an effective therapy for treating and management of refractory chronic pain. However, the complex nature of pain and infrequent in-clinic visits, determining subject's long-term response to the therapy remains difficult. Frequent measurement of pain in this population can help with early diagnosis, disease progression monitoring, and evaluating long-term therapeutic efficacy. This paper compares the utilization of the common subjective patient-reported outcomes with objective measures captured through a wearable device for predicting the response to neurostimulation therapy.

METHOD

Data is from the ongoing international prospective post-market REALITY clinical study, which collects long-term patient-reported outcomes from 557 subjects implanted by Spinal Cord Stimulator (SCS) or Dorsal Root Ganglia (DRG) neurostimulators. The REALITY sub-study was designed for collecting additional wearables data on a subset of 20 participants implanted with SCS devices for up to six months post implantation. We first implemented a combination of dimensionality reduction algorithms and correlation analyses to explore the mathematical relationships between objective wearable data and subjective patient-reported outcomes. We then developed machine learning models to predict therapy outcome based on the subject's response to the numerical rating scale (NRS) or patient global impression of change (PGIC).

RESULTS

Principal component analysis showed that psychological aspects of pain were associated with heart rate variability, while movement-related measures were strongly associated with patient-reported outcomes related to physical function and social role participation. Our machine learning models using objective wearable data predicted PGIC and NRS outcomes with high accuracy without subjective data. The prediction accuracy was higher for PGIC compared with the NRS using subjective-only measures primarily driven by the patient satisfaction feature. Similarly, the PGIC questions reflect an overall change since the study onset and could be a better predictor of long-term neurostimulation therapy outcome.

CONCLUSIONS

The significance of this study is to introduce a novel use of wearable data collected from a subset of patients to capture multi-dimensional aspects of pain and compare the prediction power with the subjective data from a larger data set. The discovery of pain digital biomarkers could result in a better understanding of the patient's response to therapy and their general well-being.

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

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

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

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

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

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

Role of patient selection and trial stimulation for spinal cord stimulation therapy for chronic non-cancer pain: a comprehensive narrative review

Background/importance

Patient selection for spinal cord stimulation (SCS) therapy is crucial and is traditionally performed with clinical selection followed by a screening trial. The factors influencing patient selection and the importance of trialing have not been systematically evaluated.

Objective

We report a narrative review conducted to synthesize evidence regarding patient selection and the role of SCS trials.

Evidence review

Medline, EMBASE and Cochrane databases were searched for reports (any design) of SCS in adult patients, from their inception until March 30, 2022. Study selection and data extraction were carried out using DistillerSR. Data were organized into tables and narrative summaries, categorized by study design. Importance of patient variables and trialing was considered by looking at their influence on the long-term therapy success.

Findings

Among 7321 citations, 201 reports consisting of 60 systematic reviews, 36 randomized controlled trials (RCTs), 41 observational studies (OSs), 51 registry-based reports, and 13 case reports on complications during trialing were included. Based on RCTs and OSs, the median trial success rate was 72% and 82%, and therapy success was 65% and 61% at 12 months, respectively. Although several psychological and non-psychological determinants have been investigated, studies do not report a consistent approach to patient selection. Among psychological factors, untreated depression was associated with poor long-term outcomes, but the effect of others was inconsistent. Most RCTs except for chronic angina involved trialing and only one RCT compared patient selection with or without trial. The median (range) trial duration was 10 (0–30) and 7 (0–56) days among RCTs and OSs, respectively.

Conclusions

Due to lack of a consistent approach to identify responders for SCS therapy, trialing complements patient selection to exclude patients who do not find the therapy helpful and/or intolerant of the SCS system. However, more rigorous and large studies are necessary to better evaluate its role.

Spinal cord stimulation in non-reconstructable critical limb ischemia: a retrospective study of 71 cases

BACKGROUND

Spinal cord stimulation (SCS) is a therapeutic option for patients with a peripheral arterial disease with critical limb ischemia (CLI) and consequent ischemic rest pain. Neuromodulation is chosen when vascular reconstruction is not possible or failed. Data about the effect of SCS over limb salvage rates are dissonant.

METHOD

We report on a retrospective cohort of CLI patients who were implanted with SCS systems between July 2010 and December 2013 in a single center. Major amputation, postoperative complications, and death were recorded.

RESULTS

Seventy-two CLI patients underwent SCS implantation, with 35 of them classified as non-reconstructable and 37 with previous but failed or only partially successful vascular procedures. A total of 21 subjects were at Fontaine's stage III (29.2%), and the remaining 51 were at stage IV (70.8%). In total, 26.4% of the patients had diabetes (n = 19), two of them at Fontaine's stage III. The mean follow-up was 17.1 ± 10.5 months. At the last follow-up, 59.2% of all patients (42/71), 85.7% of Fontaine's stage III (18/21), 48.0% of Fontaine's stage IV (24/50), and 52.6% of diabetic patients (10/19) were alive without major amputation. The probability of limb survival at 12 months was 72% for all patients, 94% for Fontaine's stage III, 62% for Fontaine's stage IV, and 61% for diabetic patients. The probability of survival at 12 months for patients who underwent major limb amputation (n = 25) was 86% with a mean survival time of 31.03 ± 4.63 months.

CONCLUSIONS

Non-reconstructable CLI patients treated with SCS can achieve meaningful clinical outcomes with few procedure-related complications. The therapy may be more beneficial in patients classified as Fontaine's Stage III.

Identifying Predictors for Early Percutaneous Spinal Cord Stimulator Explant at One and Two Years: A Retrospective Database Analysis

OBJECTIVES

Placement of percutaneous spinal cord stimulator (SCS) implant has become a therapeutic option for various chronic pain conditions; however, early surgical explant still occurs. Unfortunately, evidence regarding the incidence of early surgical explant, and patient-specific factors and comorbidities associated with such, is limited and mixed. The objective of this retrospective analysis was to elucidate the incidence and predictors of percutaneous SCS explant within the first two years of device placement.

MATERIALS AND METHODS

The PearlDiver-Mariner Patient Record Database of all payer claims was used to identify patients who underwent percutaneous lead SCS implant (leads and generator) with subsequent explant within two years of initial device implant. The primary outcome was to determine the incidence of SCS explant within the first two years of device placement. Secondary outcomes included evaluating the effects of several patient-specific comorbidities on explant rates using univariate regression analysis.

RESULTS

Across the database, a total of 52,070 patients who underwent percutaneous lead SCS implant were included, of whom 3104 (5.96%) had SCS explant within the first two years. Most explants occurred within the first-year time interval at 72.8% (2260 patients), whereas only 27.2% (844 patients) had SCS explant between years one and two. At the one-year time interval, covariates associated with an increased odds ratio (OR) (95% CI) of SCS explant were 1) depression (1.39 [1.26, 1.52]), 2) chronic preoperative (1.27 [1.16, 1.39]) or postoperative (1.23 [1,13, 1.36]) opioid use, 3) cannabis abuse (1.58 [1.20, 2.02]), 4) tobacco use (1.13 [1.04, 1.23]), and 5) coagulopathy (1.22 [1.07, 1.38]). In contrast, the OR of explant was lower in patients who were older, men, or had diabetes (complicated or uncomplicated). All associated covariates became nonsignificant after the first year of SCS implant (ie, between the first and second years), and only depression and tobacco use remained as associated factors for device explant.

CONCLUSIONS

Our retrospective analysis highlights that the rate of percutaneous SCS explant appears to considerably decrease after the first year of device implant. Furthermore, this analysis sheds additional insights into patients who may be at risk of early percutaneous SCS explant, especially within the first year of device placement, and underscores the importance of a continued multidimensional/biopsychologic assessment in patients with chronic pain.

Non-Invasive Treatments for Failed Back Surgery Syndrome: A Systematic Review

STUDY DESIGN

Systematic Review.

OBJECTIVES

The aim of this systematic review is to evaluate the efficacy of non-invasive procedures in relieving chronic pain due to Failed Back Surgery Syndrome (FBSS).

METHODS

Since patients who suffered from FBBS are often non-responders to analgesics, we compared Visual Analogical Scale for low back and leg pain, Oswestry Disability Index, trial success rate, adverse events and complications between conservative treatment groups and control groups.

RESULTS

The included studies were 15. Spinal Cord Stimulation (SCS) was performed in 11 trials; 4 studies assessed the efficacy of different epidural injections; one study evaluated repetitive Transcranial Magnetic Stimulation. All the studies reported back and leg pain relief after treatment with SCS, with a significant superiority in high frequences (HFS) group, compared to low frequences (LFS) group. Moreover, disability decreased with each non-invasive treatment evaluated. Epidural injections of steroids and hyaluronidase have shown controversial results. Adverse events were described in 7 studies: lead migration, hardware-related events, infection and incisional pain were the most reported. Finally, trial success rate showed better outcomes for HFS.

CONCLUSIONS

Our systematic review highlights the efficacy of conservative treatments in FBSS patients, with an improvement in pain scores and a decrease in disability index, especially after SCS with HFS. However, due to the lack of homogeneity among trials and population characteristics, further studies are needed to confirm the effectiveness of non-invasive interventions in patients affected by FBSS.

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

OBJECTIVE

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

METHODS

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

RESULTS

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

DISCUSSION

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

Developing Novel Therapies for Degenerative Cervical Myelopathy [AO Spine RECODE-DCM Research Priority Number 7]: Opportunities From Restorative Neurobiology

STUDY DESIGN

Narrative review.

OBJECTIVES

To provide an overview of contemporary therapies for the James Lind Alliance priority setting partnership for degenerative cervical myelopathy (DCM) question: 'Can novel therapies, including stem-cell, gene, pharmacological and neuroprotective therapies, be identified to improve the health and wellbeing of people living with DCM and slow down disease progression?'

METHODS

A review of the literature was conducted to outline the pathophysiology of DCM and present contemporary therapies that may hold therapeutic value in 3 broad categories of neuroprotection, neuroregeneration, and neuromodulation.

RESULTS

Chronic spinal cord compression leads to ischaemia, neuroinflammation, demyelination, and neuronal loss. Surgical intervention may halt progression and improve symptoms, though the majority do not make a full recovery leading to lifelong disability. Neuroprotective agents disrupt deleterious secondary injury pathways, and one agent, Riluzole, has undergone Phase-III investigation in DCM. Although it did not show efficacy on the primary outcome modified Japanese Orthopaedic Association scale, it showed promising results in pain reduction. Regenerative approaches are in the early stage, with one agent, Ibudilast, currently in a phase-III investigation. Neuromodulation approaches aim to therapeutically alter the state of spinal cord excitation by electrical stimulation with a variety of approaches. Case studies using electrical neuromuscular and spinal cord stimulation have shown positive therapeutic utility.

CONCLUSION

There is limited research into interventions in the 3 broad areas of neuroprotection, neuroregeneration, and neuromodulation for DCM. Contemporary and novel therapies for DCM are now a top 10 priority, and whilst research in these areas is limited in DCM, it is hoped that this review will encourage research into this priority.

Defining minimal clinically important differences in pain and disability outcomes of patients with chronic pain treated with spinal cord stimulation

OBJECTIVE

Minimal clinically important difference (MCID) thresholds for a limited number of outcome metrics were previously defined for patients with failed back surgery syndrome (FBSS) at 6 months after spinal cord stimulation (SCS). This study aimed to further define MCID values for pain and disability outcomes. Additionally, the authors established 1-year MCID values for outcome measures with previously defined metrics commonly used to assess SCS efficacy.

METHODS

Preoperative and 1-year postoperative outcomes were collected from 114 patients who received SCS therapy for FBSS, complex regional pain syndrome, and neuropathic pain. MCID values were established for the numerical rating scale (NRS), Oswestry Disability Index (ODI), Beck Depression Inventory (BDI), McGill Pain Questionnaire (MPQ), and Pain Catastrophizing Scale (PCS). Four established anchor-based methods were utilized to compute MCID values with two anchored questions: "Are you satisfied with SCS therapy?" and "Would you have SCS surgery again?" For each question, patients were categorized as responders if they answered "yes" or as nonresponders if they responded "no." The methodologies utilized to compute MCID scores included the average change method, minimum detectable change approach, change difference calculation, and receiver operating characteristic (ROC) analysis. Area under the ROC curve (AUC) analysis has been shown to inform the accuracy at which the MCID value can distinguish responders from nonresponders and was analyzed for each instrument.

RESULTS

For the first time, ranges of MCID values after SCS were established for MPQ (1-2.3) and PCS (1.9-13.6). One-year MCID values were defined for all indications: NRS (range 0.9-2.7), ODI (3.5-6.9), and BDI (2-5.9). AUC values were significant for NRS (0.78, p < 0.001), ODI (0.71, p = 0.003), MPQ (0.74, p < 0.001), and PCS (0.77, p < 0.001), indicating notable accuracy for distinguishing satisfied patients.

CONCLUSIONS

This was the first study to successfully determine MCID values for two prominent instruments, MPQ and PCS, used to assess pain after SCS surgery. Additionally, previously established MCID values for ODI, BDI, and the visual analog scale for patients with FBSS at 6 months after treatment were explored at 12 months for the most common indications for SCS. These data may better inform physicians of patient response to and success with SCS therapy.

Spinal cord stimulation in severe cases of complex regional pain syndrome: A retrospective cohort study with long-term follow-up

BACKGROUND

Complex regional pain syndrome (CRPS) is a debilitating pain condition often resistant to standard treatment modalities. In these cases, spinal cord stimulation (SCS) can be an option, but the effect on CRPS remains disputed. We aimed to assess the long-term effect of SCS on CRPS.

METHODS

We retrospectively analysed 51 CRPS patients implanted with an SCS system at the University Hospitals in Aarhus or Odense, Denmark, with a median follow-up time of 4.4 years. Primary outcomes were pain intensity on a numeric rating scale (NRS) and the Patients' Global Impression of Change (PGIC). Secondary outcomes were patient satisfaction, work status, consumption of pain medication, the Major Depression Inventory (MDI), Pain Catastrophizing Scale (PCS) and quality of life (QoL) measured using the Short-Form Health Survey (SF-36). For each outcome measure, baseline data were compared to the latest collected data point.

RESULTS

A significant pain relief was found with a mean reduction in NRS score of 2.4 (95% CI: 1.7-3.0, p < 0.0001). 68.8% reported 'much improved' or 'very much improved' on the PGIC scale. 87.5% would choose SCS again for the same outcome. A significant beneficial impact was found on MDI score, PCS, SF-36 summary scores and consumption of tricyclic antidepressants, antiepileptic drugs and opioids. No statistical effect was found on work status.

CONCLUSION

Pain intensity, depression, pain catastrophizing, pain medication use and QoL were significantly improved after SCS implantation, with high patient satisfaction rates in CRPS patients. This study supports the continued use of SCS in the treatment of severe CRPS.

SIGNIFICANCE

This study presents detailed data from a large, well-characterized cohort of Danish CRPS patients treated with SCS, analyzing several outcome measures. The results serve to document SCS as an effective treatment for severe CRPS and expands the cumulative level of evidence in favor of its use. Additionally, analysis of preoperative patient characteristics suggests that SCS treatment should not be withheld in patients with a high degree of psychological distress or high consumption of analgesics.

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.

Resource Use and Cost of Subcutaneous Nerve Stimulation Versus Optimized Medical Management in Patients With Failed Back Surgery Syndrome: An Analysis of the SubQStim Study

OBJECTIVES

To undertake a detailed healthcare resource use and cost analysis of the SubQStim study, which randomized patients with failed back surgery syndrome (FBSS) with low back pain to receive subcutaneous nerve field stimulation in combination with optimized medical management (treatment) or optimized medical management alone (control).

MATERIALS AND METHODS

Patient-level data from the SubQStim study were used to present descriptive analyses of healthcare resource use and estimated costs for pain medication, healthcare visits, adverse events, and device acquisition/implantation. A United Kingdom National Health Service perspective was adopted, using cost data from national tariffs, drug and device prices, and social care cost studies. Results were calculated as the mean cost per patient over the nine-month follow-up period.

RESULTS

Mean cost per patient was £18,403 in the treatment group versus £1613 in the control group. Almost 90% of the cost in the treatment group consisted of device acquisition/implantation. Higher adverse event costs were observed for patients in the treatment group, but lower costs were observed for pain medication and healthcare visits. Over nine months, opioid use decreased in the treatment group and increased in the control group. Enrolment and follow-up were terminated early in the clinical study, leading to substantial between-patient variability in each cost category.

CONCLUSIONS

Subcutaneous nerve field stimulation has the potential to offset the initial costs of the device by reducing analgesic medication and the number of healthcare visits in FBSS patients, alongside potential gains in health-related quality of life. There remains uncertainty in long-term costs and cost-effectiveness of stimulation and longer-term follow-up analyses are needed.

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.

Randomized Prospective Study in Patients With Complex Regional Pain Syndrome of the Upper Limb With High-Frequency Spinal Cord Stimulation (10-kHz) and Low-Frequency Spinal Cord Stimulation

OBJECTIVE

The objective of this prospective randomized study of cases and controls was to evaluate the efficacy of treatment with low-frequency spinal cord stimulation (LF-SCS) and 10 kHz spinal cord stimulation (10-kHz SCS) in patients diagnosed with complex regional pain syndrome type I (CRPS) with upper limb involvement.

MATERIALS AND METHODS

Fifty patients were randomized to receive conventional treatment or SCS with a commercially available low-frequency or 10-kHz system. Patients were assessed at 1, 3, 6, and 12 months. The primary endpoint was at 12-months post permanent implantation of the SCS devices. Outcome measures assessed included: Numerical Rating Scale (NRS), 12-Item Short-Format Health Survey (SF-12), Oswestry Disability Index (ODI), Study Sleep Scale medical outcomes (MOS-SS), Douleur Neuropathique 4 questions pain questionnaire (DN4), Patient Global Impression Scale on the impact of treatment improvement (PGI-I), Clinician Global Impression Scale on the impact of improving the patient (CGI-I).

RESULTS

Forty-one patients were finally included in the analysis, 19 patients in the conventional treatment group, 12 in the LF-SCS group, and 10 in the 10-kHz SCS group. At the primary endpoint, patients treated with LF-SCS presented improvements in the NRS and DN4 outcomes around 2.4 and 1.5 times above the minimal clinically important difference (MCID) thresholds. At the primary endpoint, patients treated with 10-kHz SCS presented improvements in the NRS and DN4 outcomes around 2 and 1.4 times above the MCID thresholds.

CONCLUSIONS

Patients experienced considerable improvement after SCS. The results show that LF-SCS has very good results when compared with conventional treatment. The results obtained with 10-kHz SCS are encouraging, with the advantages of the absence of paresthesia making it an alternative in the treatment of CRPS.

Multicentre, clinical trial of burst spinal cord stimulation for neck and upper limb pain NU-BURST: a trial protocol

BACKGROUND

Spinal cord stimulation (SCS) is an established therapy for chronic neuropathic pain and most frequently utilised for Failed Back Surgery Syndrome (FBSS). BurstDR™ also known as DeRidder Burst-SCS, a novel waveform, has demonstrated superiority to conventional tonic stimulation of the thoracic spine in FBSS. There are case reports of an improvement in multidimensional pain outcomes using DeRidder Burst-SCS in the cervical spine for chronic neck and cervical radicular pain. The safety and efficacy of cervical DeRidder Burst-SCS stimulation still however remain undetermined.

METHODS/DESIGN

This is a prospective, multicentre feasibility trial evaluating the safety and therapeutic efficacy of DeRidder Burst-SCS stimulation for the treatment of chronic intractable neck pain with or without radiation to the arm, shoulder, and upper back. After baseline evaluation, subjects will undergo an SCS trial using the Abbott Invisible Trial system according to standard clinical procedures. During the trial phase, SCS leads will be implanted in the cervical epidural space. At the end of the SCS trial, subjects experiencing at least 50% pain relief will be considered for permanent implant. Pain intensity, medication usage, and other multidimensional pain outcomes will be collected. The timing of these will be at baseline, end of the SCS trial and at 3-, 6-, and 12-month visits. Incidence of adverse events will be collected throughout the study duration.

DISCUSSION

The results of this feasibility study will validate the efficacy and safety of DeRidder Burst-SCS stimulation in the cervical spine. The results obtained in this study will potentially be used to generate a level 1 evidence-based study with formal statistical hypotheses testing.

TRIAL REGISTRATION

www.clinicaltrials.gov Identifier: NCT03159169.

Neuromodulation for Medically Refractory Neuropathic Pain: Spinal Cord Stimulation, Deep Brain Stimulation, Motor Cortex Stimulation, and Posterior Insula Stimulation

BACKGROUND

The treatment of neuropathic pain (NP) continues to be controversial as well as an economic health issue and a challenge to health care. Neurosurgery can offer different methods of neuromodulation that may improve patients' condition, including deep brain stimulation (DBS), motor cortex stimulation (MCS), spinal cord stimulation (SCS), and posterior insula stimulation (PIS). There is no consensus of opinion as to the final effects of these procedures, which stimulation parameters to select, the correct timing, or how to select the patients who will best benefit from these procedures.

OBJECTIVE

To review the evidence available regarding these 4 procedures and the management of NP.

METHODS

We conducted a PubMed, Embase, and Cochrane Library database search from 1990 to 2020. The strategy of the search concentrated on the following keywords: "neuropathic pain," "chronic pain," "deep brain stimulation," "motor cortex stimulation," "spinal cord stimulation," "insula stimulation," and "neuromodulation." Studies that provided data regarding the immediate and long-term effectiveness of the procedure, anatomic stimulation target, percentage of pain control, and cause of the NP were included.

RESULTS

The most frequent causes of NP were phantom limb pain and central poststroke pain in the MCS group; central poststroke pain, phantom limb pain, and spinal cord injury (SCI) in the DBS group; and complex regional pain syndrome and failed back surgery syndrome in the SCS group. Pain improvement varied between 35% and 80% in the MCS group and 50% and 60% in the DBS group. In the SCS group, successful rates varied between 38% and 89%.

CONCLUSIONS

This systematic review highlights the literature supporting SCS, DBS, MCS, and PIS methods for the treatment of NP. We found consistent evidence supporting MCS, DBS, and SCS as possible treatments for NP; however, we were not able to define which procedure should be indicated for each cause. Furthermore, we did not find enough evidence to justify the routine use of PIS. We conclude that unanswered points need to be discussed in this controversial field and emphasize that new research must be developed to treat patients with NP, to improve their quality of life.

[Spinal cord stimulation in the treatment of chronic pain]

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

Improved Psychosocial and Functional Outcomes and Reduced Opioid Usage Following Burst Spinal Cord Stimulation

Objective

Burst spinal cord stimulation (B‐SCS) has been shown to reduce neuronal firing in the anterior cingulate cortex through selective modulation of the medial pain pathway tract. This pain pathway communicates the affective component of pain processing. The purpose of this study was to assess the effect of B‐SCS on psychosocial functioning and its influence on pain and quality of life.

Materials and Methods

Eligible patients with chronic, intractable pain of the trunk, and/or lower limbs were enrolled. After a successful trial period, subjects received a permanent implant and returned for follow‐up at 6‐ and 12‐months.

Results

In total, 269 patients were enrolled at 22 centers. Trial success rate was 90%. Significant improvements in pain, physical, mental, and emotional functioning were observed from baseline to the 6‐ and 12‐month follow‐up (p < 0.001). Overall, patients had improved quality of life, became more active, and the negative impact of pain on daily life was decreasing. At one year, 81% of subjects were satisfied or very satisfied with their therapy. Subjects showing significant improvements on mental health outcomes reported enhanced pain relief and quality of life scores compared with subjects with continued impaired mental health at follow‐up. At one year, 89% of subjects who were taking opioids at baseline decreased or stayed at the same level of opioid use; 19% stopped taking any opioids. No unanticipated adverse events have been reported.

Conclusions

One‐year outcomes after B‐SCS show improvements across all evaluated psychological measures with the largest impact observed on catastrophizing and depression (the affective component of pain processing). These pain‐related beliefs and behaviors, and not pain intensity, have been shown to put patients at greatest risk of a poor prognosis and quality of life.

Spinal cord stimulation in chronic pain: technical advances

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

Active Recharge Burst and Tonic Spinal Cord Stimulation Engage Different Supraspinal Mechanisms: A Functional Magnetic Resonance Imaging Study in Peripherally Injured Chronic Neuropathic Rats

OBJECTIVES

To assess the supraspinal working mechanisms of the burst spinal cord stimulation (SCS) mode, we used functional magnetic resonance imaging (fMRI) in chronic neuropathic rats. We hypothesized that active recharge burst SCS would induce a more profound blood oxygenation level-dependent (BOLD) signal increase in areas associated with cognitive-emotional aspects of pain, as compared to tonic SCS.

METHODS

Sprague Dawley rats (n = 17) underwent a unilateral partial sciatic nerve ligation, which resulted in chronic neuropathic pain. Quadripolar SCS electrodes were epidurally positioned on top of the dorsal columns at Th13. Isoflurane-anesthetized (1.5%) rats received either tonic SCS (n = 8) or burst SCS (n = 9) at 66% of motor threshold. BOLD fMRI was conducted before, during, and after SCS using a 9.4-T horizontal bore scanner.

RESULTS

Overall, both tonic and burst SCS induced a significant increase of BOLD signal levels in areas associated with the location and intensity of pain, and areas associated with cognitive-emotional aspects of pain. Additionally, burst SCS significantly increased BOLD signal levels in the raphe nuclei, nucleus accumbens, and caudate putamen. Tonic SCS did not induce a significant increase in BOLD signal levels in these areas.

CONCLUSIONS

In conclusion, active recharge burst and tonic SCS have different effects on the intensity and localization of SCS-induced activation responses in the brain. This work demonstrates that active recharge burst is another waveform that can engage brain areas associated with cognitive-emotional aspects of pain as well as areas associated with location and intensity of pain. Previous studies showing similar engagement used only passive recharge burst.

Burst and Tonic Spinal Cord Stimulation Both Activate Spinal GABAergic Mechanisms to Attenuate Pain in a Rat Model of Chronic Neuropathic Pain

BACKGROUND

Experimental and clinical studies have shown that tonic spinal cord stimulation (SCS) releases gamma-aminobutyric acid (GABA) in the spinal dorsal horn. Recently, it was suggested that burst SCS does not act via spinal GABAergic mechanisms. Therefore, we studied spinal GABA release during burst and tonic SCS, both anatomically and pharmacologically, in a well-established chronic neuropathic pain model.

METHODS

Animals underwent partial sciatic nerve ligation (PSNL). Quantitative immunohistochemical (IHC) analysis of intracellular GABA levels in the lumbar L4 to L6 dorsal spinal cord was performed after 60 minutes of burst, tonic, or sham SCS in rats that had undergone PSNL (n = 16). In a second pharmacological experiment, the effects of intrathecal administration of the GABA_A antagonist bicuculline (5 μg) and the GABA_B antagonist phaclofen (5 μg) were assessed. Paw withdrawal thresholds to von Frey filaments of rats that had undergone PSNL (n = 20) were tested during 60 minutes of burst and tonic SCS 30 minutes after intrathecal administration of the drugs.

RESULTS

Quantitative IHC analysis of GABA immunoreactivity in spinal dorsal horn sections of animals that had received burst SCS (n = 5) showed significantly lower intracellular GABA levels when compared to sham SCS sections (n = 4; P = 0.0201) and tonic SCS sections (n = 7; P = 0.0077). Intrathecal application of the GABA_A antagonist bicuculline (5 μg; n = 10) or the GABA_B antagonist phaclofen (5 μg; n = 10) resulted in ablation of the analgesic effect for both burst SCS and tonic SCS.

CONCLUSIONS

In conclusion, our anatomical and pharmacological data demonstrate that, in this well-established chronic neuropathic animal model, the analgesic effects of both burst SCS and tonic SCS are mediated via spinal GABAergic mechanisms.

Spinal Cord Stimulation in Patients With Chronic Pain and Restless Legs Syndrome: A Case Report

Restless legs syndrome can be a debilitating condition that affects a patient's ability to function and their quality of life. Neuromodulation may represent a potential option for nonpharmacological management of restless legs syndrome. We present 3 patients who have a chronic pain diagnosis and medically refractory restless legs syndrome that warranted neuromodulation. After neuromodulation, all 3 patients had improvement in their restless legs syndrome symptoms and were taking less pain medication, and 2 out of 3 had significantly improved functionality at short-term follow-up. This case series suggests that spinal cord stimulation may be a viable nonpharmacological treatment option for medically refractory restless legs syndrome.

Spinal Cord Stimulation in Pregnant Patients: Current Perspectives of Indications, Complications, and Results in Pain Control: A Systematic Review

Spinal cord stimulation (SCS) has been described as a valuable neuromodulator procedure in the management of chronic medically untreated neuropathic pain. Although the use of this technique has been published in many papers, a question still remains regarding its applicability in pregnant patients. The goal of this paper is to discuss the risks, complications, and results as well as the prognosis of SCS in pregnant patients. We performed a systematic review from 1967 to 2018 using the databases MEDLINE, LILACS, SciELO, PubMed, and BIREME, utilizing language as selection criteria. Eighteen studies that met our criteria were found and tabulated. SCS is a reversible and adjustable surgical procedure, which results in patients that demonstrated a significant effect in the reduction of pain intensity in pregnant patients. The etiologies most frequent were complex regional pain and failed back pain syndromes, which together represented 94% of analyzed cases. The technical complications most frequent were lead migration (3%, n = 1). Regarding the risks, the authors did not show significative factors among the categorical variables that can suggest a teratogenicity, while the maternal risks have been associated to the consequences of technical complications due to, among other factors, improvement of abdominal pressure during pregnancy and delivery. Finally, although there are not significative cohorts of pregnant patients, the procedure is still an effective surgical approach of neuropathic pain associated to lower rates of complications and significative improvement in the quality of life of patients during pregnancy.

Spinal Cord Stimulation as Treatment for Truncal Chronic Regional Pain Syndrome After Cardiac Surgery: A Case Report

A 59-year-old man presented 7 months after coronary artery bypass with continued bilateral axillary pain. His symptoms progressed over a period of months to allodynia, edema, erythema, decreased range of motion, and skin changes consistent with complex regional pain syndrome type I. After failing multiple treatment options, the patient underwent a trial of spinal cord stimulation. Leads positioned in the posterior epidural space from the seventh cervical to the third thoracic vertebral levels resulted in complete paresthesia coverage of his truncal chronic regional pain syndrome (CRPS) and the stimulation was associated with almost complete resolution of CRPS. This case report suggests that spinal cord stimulation may provide effective treatment for truncal CRPS after coronary artery bypass graft surgery.

Novel Technique for Insertion of Cervical Spinal Cord Stimulator Percutaneous Leads: Technical Note and Institutional Experience

OBJECTIVE

Cervical spinal cord stimulation is a safe and effective treatment for chronic axial neck pain and upper limb neuropathic pain. We report our novel institutional experience with performing cervical spinal cord stimulation trials with patients placed in an upright sitting position. This allows easy access to the cervical epidural space and has the added benefit of unobstructed access to the airway.

METHODS

We retrospectively reviewed data for patients who had undergone cervical spinal cord stimulation trial procedures in an upright, sitting position at the Vanderbilt University Medical Center. Demographic information including age, gender, preoperative diagnosis, progression to permanent implant after a successful trial, and operative time in minutes was collected.

RESULTS

A detailed description of the technique for implantation of cervical spinal cord stimulator trial leads in an upright sitting position is described. A total of 29 patients were implanted; 16 (55%) were female. Mean operative time was 78 minutes from incision to closing. The majority of patients (25/29; 86%) had successful trials and proceeded to permanent implant. No complications occurred, and the procedure was well tolerated by all patients.

CONCLUSIONS

Cervical spinal cord stimulation trials performed in an upright, sitting position allow for easy epidural access and an unobstructed airway with reasonable setup time.

A Randomized Controlled Trial of Subcutaneous Nerve Stimulation for Back Pain Due to Failed Back Surgery Syndrome: The SubQStim Study

Objectives

To compare the effectiveness of peripheral nerve stimulation utilizing a subcutaneous lead implant technique—subcutaneous nerve stimulation (SQS) plus optimized medical management (SQS + OMM arm) vs. optimized medical management alone (OMM arm) in patients with back pain due to failed back surgery syndrome.

Patients and Methods

Patients were recruited from 21 centers, in Europe, Israel, and Australia. Eligible patients were randomized (1:1) to SQS + OMM or OMM arms. Those in the SQS arm were implanted with a neurostimulator and up to two subcutaneous percutaneous cylindrical leads in the area of pain. Patients were evaluated pre‐randomization and at one, three, six, and nine months post‐randomization. The primary endpoint was the proportion of subjects with a ≥50% reduction in back pain intensity (“responder”) from baseline to nine months. Secondary outcomes included proportion of responders with a ≥50% reduction in back pain intensity at six months and ≥30% reduction at nine months, and the mean change from baseline in back pain intensity at six and nine months between the two arms.

Results

Due to the slow rate of recruitment, the study was terminated early with 116 subjects randomized. A total of 33.9% (19/56, missing: n = 20 [36%]) of subjects in the SQS + OMM arm and 1.7% (1/60, missing: n = 24 [40%]) in the OMM arm were responders at Month 9 (p < 0.0001). Secondary objectives showed a significant difference in favor of SQS + OMM arm.

Conclusion

The results indicate that the addition of SQS to OMM is more effective than OMM alone in relieving low back pain at up to nine months.

Effectiveness of complex regional pain syndrome treatment: A systematic review

Complex regional pain syndrome (CRPS) is a descriptive term for a complex of symptoms and signs typically occurring following trauma of the extremity. Typical symptomatology includes severe pain, swelling, vasomotor instability and functional impairment of the affected limb. At present there is no one, effective method of treatment of the condition. A large number of treatments have been investigated but major multicentre randomized controlled trials are lacking. This study presents the results of a systematic review of the evidence on effectiveness of treatment methods in CRPS. It is a follow-up to earlier reviews of randomized controlled trials on CRPS treatment published between 1966 and 2016.

RESULTS

The review of randomized controlled trials showed that only bisphosphonates were found to give uniformly positive effects, statistically significantly better than placebo. Improvement has been reported with topical dimethyl sulfoxide, systemic steroids, spinal cord stimulation and graded motor imagery/mirror therapy programmes. The available evidence does not support the use of other treatments in CRPS, however they are frequently used in clinical practice.

CONCLUSION

Available evidence, although numerous, does not necessarily reflect what is truly effective and what is sham in the management of CRPS.

The Factors Affecting the Difficulty of Percutaneous Cylindrical Electrode Placement for Spinal Cord Stimulation

OBJECTIVE

Optimal placement of electrodes is important for spinal cord stimulation. Factors affecting the difficulty of percutaneous electrode placement are not well known. In this study, we retrospectively evaluated the factors affecting the difficulty of percutaneous electrode placement.

METHODS

We performed a retrospective analysis of 90 consecutive procedures of percutaneous cylindrical electrode implantation at the first author's institution. Age, sex, smoking state, body mass index, the duration of time from the beginning of pain syndrome to operation, diagnosis, the number of previous electrode placements, the previous electrode implantation period, the presence of axial low back pain, the electrode tip level, the pattern of electrode placement, and the reason for reimplantation were selected as factors associated with the success of electrode placement or the operation time of electrode placement.

RESULTS

The number of previous electrode placements and the electrode tip level were independently associated with the operation time of electrode placement. According to both univariable and multivariable regression analyses, 1 previous electrode placement lengthened the operation time by approximately 15 minutes. No factors were significantly associated with the success of electrode placement. The more frequently that previous electrode placement was performed, the more difficult electrode placement tended to be. However, electrode reimplantation can be successful given extra time.

CONCLUSIONS

This is the first study to evaluate factors affecting the difficulty of percutaneous electrode placement. A history of percutaneous cylindrical electrode placement did not affect the success of current placement, although it lengthened the operation time.

Prevalence and Cost Analysis of Complex Regional Pain Syndrome (CRPS): A Role for Neuromodulation

OBJECTIVE

The diagnosis and treatment of complex regional pain syndrome (CRPS) is challenging and there is a paucity of data describing its overall cost burden and quantifying its impact on the US healthcare system. The aim of this study was to assess the prevalence and healthcare utilization costs associated with CRPS.

MATERIALS AND METHODS

A retrospective longitudinal study was performed using the Truven MarketScan® database to identify patients with a new indexed diagnosis of CRPS (Type I, II, or both) from 2001 to 2012. We collected total, outpatient, and pain prescription costs three years prior to CRPS diagnosis (baseline), at year of CRPS diagnosis, and eight-year post-CRPS diagnosis. A longitudinal multivariate analysis was used to model the estimated total and pain prescription cost ratios comparing patients diagnosed before and after CRPS.

RESULTS

We included 35,316 patients with a newly indexed diagnosis of CRPS (Type I: n = 18,703, Type II: n = 14,599, Unspecified: n = 2014). Baseline characteristics were similar between the CRPS cohorts. Compared to two- and three-year baseline costs, one-year prior to diagnosis for all CRPS patients yielded the highest interquartile median [IQR] costs: total costs $7904[$3469, $16,084]; outpatient costs $6706[$3119, $12,715]; and pain prescription costs $1862[$147, $7649]. At the year of CRPS diagnosis, the median [IQR] costs were significantly higher than baseline costs: total costs $8508[$3943, $16,666]; outpatient costs $7251[$3527, $13,568]; and pain prescription costs $2077[$140, $8856]. Over the eight-year period after CRPS diagnosis, costs between all the years were similar, ranging from the highest (one-year) to lowest (seven-years), $4845 to $3888. The median total cumulative cost 8-years after CRPS diagnosis was $43,026 and $12,037 for pain prescription costs. [Correction added on 06 November 2017 after first online publication: the preceding sentence has been updated to demonstrate the median cumulative cost in replacement of the additive cumulative mean costs.]. During the CRPS diagnosis period, patients are expected to have a total cost 2.17-fold and prescription cost 2.56-fold of their baseline cost annually.

CONCLUSIONS

Our study demonstrates that there is a significant increase in cost and healthcare resource utilization one-year prior to and around the time of CRPS diagnosis. Furthermore, there is an increased annual cost post-diagnosis compared to baseline costs prior to CRPS diagnosis.

Electrical Neuromodulation of the Respiratory System After Spinal Cord Injury

Spinal cord injury (SCI) is a complex and devastating condition characterized by disruption of descending, ascending, and intrinsic spinal circuitry resulting in chronic neurologic deficits. In addition to limb and trunk sensorimotor deficits, SCI can impair autonomic neurocircuitry such as the motor networks that support respiration and cough. High cervical SCI can cause complete respiratory paralysis, and even lower cervical or thoracic lesions commonly result in partial respiratory impairment. Although electrophrenic respiration can restore ventilator-independent breathing in select candidates, only a small subset of affected individuals can benefit from this technology at this moment. Over the past decades, spinal cord stimulation has shown promise for augmentation and recovery of neurologic function including motor control, cough, and breathing. The present review discusses the challenges and potentials of spinal cord stimulation for restoring respiratory function by overcoming some of the limitations of conventional respiratory functional electrical stimulation systems.

Defining low anterior resection syndrome: a systematic review of the literature

AIM

There is increasing awareness of the poor functional outcome suffered by many patients after sphincter-preserving rectal resection, termed 'low anterior resection syndrome' (LARS). There is no consensus definition of LARS and varying instruments have been employed to measure functional outcome, complicating research into prevalence, contributing factors and potential therapies. We therefore aimed to describe the instruments and outcome measures used in studies of bowel dysfunction after low anterior resection and identify major themes used in the assessment of LARS.

METHOD

A systematic review of the literature was performed for studies published between 1986 and 2016. The instruments and outcome measures used to report bowel function after low anterior resection were extracted and their frequency of use calculated.

RESULTS

The search revealed 128 eligible studies. These employed 18 instruments, over 30 symptoms, and follow-up time periods from 4 weeks to 14.6 years. The most frequent follow-up period was 12 months (48%). The most frequently reported outcomes were incontinence (97%), stool frequency (80%), urgency (67%), evacuatory dysfunction (47%), gas-stool discrimination (34%) and a measure of quality of life (80%). Faecal incontinence scoring systems were used frequently. The LARS score and the Bowel Function Instrument (BFI) were used in only nine studies.

CONCLUSION

LARS is common, but there is substantial variation in the reporting of functional outcomes after low anterior resection. Most studies have focused on incontinence, omitting other symptoms that correlate with patients' quality of life. To improve and standardize research into LARS, a consensus definition should be developed, and these findings should inform this goal.

Spinal Cord Stimulation Treatment for Persistent Pain After a Burn Injury: A Case Report

Spinal cord stimulation (SCS) is used to treat neuropathic pain, but there are no published studies on its use to treat burn pain. We used SCS to treat a 67-year-old man suffering from burn pain that could not be managed with high-dose opioids or adjuvant neuropathic analgesics. A trial of SCS markedly reduced the visual analog scale score for pain in the left lateral abdominal and gluteal regions. He underwent permanent implantation of a SCS and achieved an opioid-free state. This case suggests that SCS treatment is a therapeutic option for burn pain refractory to conventional therapy.

Cost-Effectiveness Data Regarding Spinal Cord Stimulation for Low Back Pain

STUDY DESIGN

Review of published literature pertaining to spinal cord stimulation (SCS) cost data analysis.

OBJECTIVE

To acquire, organize, and succinctly summarize the available literature regarding the costs associated with, and the cost-effectiveness of, SCS.

SUMMARY OF BACKGROUND DATA

Chronic back and limb pain is a pervasive complaint in modern society, with estimated annual costs of medical care greater than $100 billion. The traditional standard medical management with or without intermittent surgical decompression/fusion has been plagued by high costs and inconsistent results, leading to poor patient satisfaction and functional outcome, and questions from policy makers regarding use of limited healthcare resources. Neuromodulation techniques, including SCS have recently become more common in the treatment of chronic back/leg pain, with clinical studies showing a high degree of efficacy in alleviating otherwise intractable pain. Given the relatively high upfront costs associated with the hardware and implantation, policy makers have, however, questioned their use in the framework of cost-containment and resource utilization. We reviewed the available literature summarizing cost data of SCS in chronic back and limb pain, as an understanding of these data will be vital to justify continued payment for this expensive, but often very effective, treatment modality.

METHODS

We performed a PubMed literature search utilizing the following terms: "spinal cord stimulation," "SCS," "financial," "cost," "cost-effectiveness," and "cost-utility." All studies published in English and containing complete or partial cost evaluations of SCS for chronic back and limb pain were included.

RESULTS

The search revealed 21 studies that evaluated cost data, with or without outcomes analysis and cost-utility analysis, for patients with chronic back and limb pain. The overwhelming majority of data presented shows that SCS is not only an effective treatment option for these patients, but also represents cost savings and efficient use of healthcare resources relative to current standards of care. Although not all studies performed cost-utility analyses, those that did tended to show SCS falling well within accepted thresholds of "willingness-to-pay" on the part of third-party payers. That being said, the articles included in this review were almost all small, retrospective, single-institution studies. In addition, many of them relied on modeling for their analyses, and published literature values for cost and/or outcomes data rather than prospectively collected patient data. Although the data presented in this review are encouraging, it should serve as a foundation for a thorough, prospective, cost-utility analysis of SCS in chronic back and limb pain so that the role of this important treatment modality may be cemented in the treatment paradigm for these patients without questions from third-party payers.

CONCLUSION

The large majority of data covering costs of SCS argue in favor of the cost-effectiveness of this treatment modality for chronic neuropathic pain, especially in comparison to reoperation and medical management. Although most of the higher-quality evidence is relatively short-term, clinical experience with the durability of treatment benefit of SCS in these patients is promising. Given the pushback regarding high upfront costs of implantation, longer-term, prospective, randomized studies evaluating this topic will be important to help maintain third-party payer reimbursements for SCS.

LEVEL OF EVIDENCE

5.