New Therapy for Refractory Chronic Mechanical Low Back Pain-Restorative Neurostimulation to Activate the Lumbar Multifidus: One Year Results of a Prospective Multicenter Clinical Trial

Systematic Review and Meta-analysis of Stimulation of the Medial Branch of the Lumbar Dorsal Rami for the Treatment of Chronic Low Back Pain

INTRODUCTION

Chronic low back pain (CLBP) is often associated with impaired motor control and degeneration of the lumbar multifidus muscles. Several studies have reported on the utility of multifidus or medial branch stimulation as a treatment. We present a systematic review and meta-analysis of studies reporting on the change in low back pain intensity with multifidus stimulation.

MATERIALS AND METHODS

A comprehensive literature search was conducted from 2010 to 2022 for randomized controlled trials or prospective reports in adults with CLBP, treated with multifidus or medial nerve stimulation through implanted or percutaneous device. Mean change (standard error) in pain intensity was extracted and data synthesized using a mixed effects regression with a random intercept for the study to account for repeated time points.

RESULTS

A total of 419 participants were enrolled in six studies; there were 25 effects (one to six time points per study), with follow-ups ranging from 1.5 to 48 months. The weighted pooled mean effect was a reduction in pain intensity (0-10 scale) of 2.9 units (95% CI: 2.1-3.7). The 95% prediction interval was a reduction in pain intensity of 0.6 to 5.2 units. The estimated probability of a reduction in pain of >two units in a new similar study is 0.84 (0.68-0.98). Meta-regression revealed that a longer follow-up time was associated with greater reductions in pain (0.25 units [0.16-0.34] per six months).

CONCLUSIONS

Medial branch stimulation for the treatment of CLBP shows a high probability of a clinically significant change in pain intensity. Longer duration of stimulation was associated with decreased low back pain intensities.

Correlating Evoked Electromyography and Anatomic Factors During Spinal Cord Stimulation Implantation With Short-Term Outcomes

INTRODUCTION

We examine ways intraoperative neuromonitoring during spinal cord stimulation (SCS) varies between a high-resolution investigational SCS (HR-SCS) paddle and a commercial paddle. Furthermore, the presence of evoked motor responses (eg, electromyography [EMG]) in painful regions during surgery is correlated to outcomes.

MATERIALS AND METHODS

We used HR-SCS to assess EMG response from 18 patients (NCT05459324). Maximum percentage change in root mean squared (maxRMS) EMG values was determined. Correlations were performed with magnetic resonance imaging measurements and patient outcomes collected preoperatively and at three months (numerical rating scale [NRS], McGill Pain, Beck Depression Inventory, Oswestry Disability Index [ODI], and Pain Catastrophizing Score).

RESULTS

Of the 18 patients (12 women to six men; mean age 56 years; eight with neuropathic pain, eight with persistent spinal pain syndrome, two with complex regional pain syndrome), nine had a response at three months based on 50% reduction in NRS, 14 by achieving minimal clinically important difference (MCID) on NRS, and 11 by reaching MCID on ≥three outcome metrics. The anterior posterior diameter (APD) of the spinal column at level of testing correlated with all three responses (p < 0.05). We examined RMS at muscles correlating with individual patient pain distributions and found correlations between RMS and MCID NRS and MCID ODI (p < 0.05). maxRMS in abductor hallucis correlated with improvement in NRS and ODI across the group (p < 0.05).

CONCLUSIONS

We found that eliciting EMGs over the painful areas during surgery caused alleviation of pain intensity and disability. Obtaining stimulation of abductor hallucis (AH) was more predictive of pain improvement than any other muscle group, and APD alone correlated with improvements in pain intensity and holistic outcomes. These pilot data suggest that implanters should consider APD and EMG responses from painful regions and AH during surgery.

Efficacy of Self-Natural Posture Exercise (SNPE) programs on chronic low back pain: A randomized controlled feasibility trial with waitlist control

BACKGROUND

Low back pain (LBP) is a significant source of disability and decreased quality of life. The Self-Natural Posture Exercise (SNPE) intervention can be used effectively in many cases, but feasibility and impact has not been fully explored.

OBJECTIVE

The current study explores the feasibility and efficacy of face-to-face (FtF) and virtual (Vir) SNPE programs on chronic low back pain.

METHODS

This is a randomized single-blinded waitlist control study with 10 participants in the FtF group (age 45.8 ± 2.89) and 9 in the Vir group (age 52.2 ± 2.3). Participants had low to moderate low back pain for > 3 months. Those who would eventually become the Vir group served initially as a waitlist control (Con) group. The FtF group received 12 weeks of in-person exercise training sessions conducted and the Vir group received weekly recorded training videos created by and featuring the same instructor. Measured outcomes included feasibility assessed by rate of retention and rate of attendance, level of low back pain (Oswestry Disability Index, Visual Analogue Scale), quality of life (36-Item Short Form Health Survey 1.0), muscular pressure pain threshold, and muscle tone. Analysis was done via repeated measures ANOVA and Wilcoxon tests.

RESULTS

Rates of retention were 80% in the FtF group and 78% in the Vir group. Attendance rates were 88% in the FtF group and 60% in the Vir group. ODI, VAS, and some SF-36 domains improved in both the FtF and Vir groups. Overall, the FtF group improved in more domains and by a larger degree than the Vir group and both groups improved relative to Con.

CONCLUSION

A 12-week SNPE program, done virtually or in person, shows promise in improving ODI, VAS, and some SF-36 domains. FtF appears to be more effective. Future studies would benefit from sampling a larger and more diverse population.

Precision Rehabilitation After Neurostimulation Implantation for Multifidus Dysfunction in Nociceptive Mechanical Chronic Low Back Pain

Chronic low back pain (CLBP) is a debilitating, painful, and costly condition. Implantable neuromuscular electrical stimulation targeting the multifidus musculature is growing as a non-pharmacologic option for patients with recalcitrant nociceptive mechanical CLBP who have failed conservative treatments (including medications and physical therapy) and for whom surgery is not indicated. Properly selecting patients who meet specific criteria (based on historical results from randomized controlled trials), who diligently adhere to implant usage and precisely implement neuromuscular rehabilitation, improve success of significant functional recovery, as well as pain medication reductions. Patients with nociceptive mechanical CLBP who underwent implanted multifidus neurostimulation have been treated by physicians and rehabilitation specialists who have honed their experience working with multifidus neurostimulation. They have collaborated on consensus and evidence-driven guidelines to improve quality outcomes and to assist providers when encountering patients with this device. Physicians and physical therapists together provide precision patient-centric medical management with quality neuromuscular rehabilitation to encourage patients to be experts of both their implants and quality spine motion to help override long-standing multifidus dysfunction related to their CLBP.

Healthcare resource utilization for chronic low back pain among high-utilizers

BACKGROUND

Chronic low back pain is a leading cause of morbidity and is among the largest cost drivers for the healthcare system. Research on healthcare resource utilization of patients with low back pain who are not surgical candidates is limited, and few studies follow individuals who generate high healthcare costs over time.

PURPOSE

This claims study aimed to identify patients with high-impact mechanical, chronic low back pain (CLBP), quantify their low back pain-related health resource utilization, and explore associated patient characteristics. We hypothesize that patients in the top quartile of healthcare resource utilization in the second year after initial diagnosis will continue to generate considerable back pain-related costs in subsequent years.

STUDY DESIGN/SETTING

IBM MarketScan Research Databases from 2009-2019 were retrospectively analyzed.

PATIENT SAMPLE

Adults in the United States with an initial diagnosis of low back pain between 2010 and 2014 who did not have cancer, spine surgery, recent pregnancy, or inflammatory spine conditions, were identified using the International Classification of Diseases (ICD) and Current Procedural Terminology (CPT) codes. To ensure patients had chronic low back pain, it was required that individuals had additional claims with a low back pain diagnosis 6 to 12 and 12 to 24 months after initial diagnosis.

OUTCOME MEASURES

Cost and utilization of inpatient visits, outpatient visits, emergency room visits, pharmacologic and nonpharmacologic treatment options and imaging for chronic low back pain.

METHODS

Annual back pain-related costs and the use of pharmacologic and nonpharmacologic treatments for 5 years were analyzed. Logistic regression was utilized to identify factors associated with persistent high spending.

RESULTS

Of 16,917 individuals who met the criteria for chronic low back pain, 4,229 met the criteria for having high healthcare utilization, defined as being in the top quartile of back pain-related costs in the 12 to 24 months after their initial diagnosis. The mean and median back pain-related cost in the first year after an initial diagnosis was $7,112 (SD $9,670) and $4,405 (Q1 $2,147, Q3 $8,461). Mean and median back pain related costs in the second year were $11,989 (SD $20,316) and $5,935 (Q1 $3,892, Q3 $10,678). Costs continued to be incurred in years 3 to 5 at a reduced rate. The cumulative mean cost for back pain over the 5 years following the initial diagnosis was $31,459 (SD $39,545). The majority of costs were from outpatient services. Almost a quarter of the high utilizers remained in the top quartile of back pain-related costs during years 3 to 5 after the initial diagnosis, and another 19% remained in the top quartile for 2 of the 3 subsequent years. For these two groups combined (42%), the 5-year cumulative mean cost for back pain was $43,818 (SD $48,270). Patient characteristics associated with a higher likelihood of remaining as high utilizers were diabetes, having a greater number of outpatient visits and pharmacologic prescriptions, and lower utilization of imaging services.

CONCLUSION

This is one of the first studies to use an administrative claims database to identify high healthcare resource utilizers among a population of United States individuals with nonsurgical, chronic low back pain and follow their utilization over time. There was a population of individuals who continued to experience high costs 5 years beyond their initial diagnosis, and the majority of individuals continued to seek outpatient services. Further longitudinal claims research that incorporates symptom severity is needed to understand the economic implications of this condition.

Is it possible to generate an additional pleasant and pain-relieving muscle stimulation when using a low-frequency spinal cord stimulation (SCS) for the treatment of lower back pain? Pilot study: A new technique: "MuscleSCS"

OBJECTIVE

The combined use of spinal cord stimulation (SCS) and muscle stimulation, in the treatment of chronic pain, using the same probe, could improve the clinical results. However, this technique has not been established as yet. It was our hypothesis that it is possible to generate muscle stimulation by using low frequencies with SCS electrodes and use it to additionally treat chronic back pain.

METHODS

We generated muscle stimulation in patients with previously implanted SCS electrodes, for the treatment of lower back pain, by using low frequencies (2, 4, 6, and 8 Hz) and different contact combinations of the electrodes. The results were evaluated by using visual inspection (videos), haptic control, surface electromyography (EMG), and sonographic recordings.

RESULTS

This pilot study (17 patients, seven females, age 36-87 years, 11 percutaneous paddle leads, and 6 octrodes) was performed at the Neurosurgical Department of the University of Tuebingen. The most preferred frequencies were 6 Hz (45.5% of percutaneous paddle leads) and 8 Hz (50% of octrodes) at contacts 3&4 or 5&6. The preference of frequencies differed significantly among genders (p = 0.023). Simultaneous EMG and ultrasonic recordings demonstrated the generation of muscle potentials and the stimulation of deeper muscle groups.

CONCLUSION

In this study, it has been shown that with low-frequency SCS stimulation, pleasant and pain-relieving muscle contractions of the lower and upper back can also be generated. This combined method has been coined by us as "MuscleSCS" technique. Clinical trials are necessary to establish the value of this combined technique and its subtypes.

Multifidus dysfunction and restorative neurostimulation: a scoping review

OBJECTIVE

Chronic low back pain (CLBP) is multifactorial in nature, with recent research highlighting the role of multifidus dysfunction in a subset of nonspecific CLBP. This review aimed to provide a foundational reference that elucidates the pathophysiological cascade of multifidus dysfunction, how it contrasts with other CLBP etiologies and the role of restorative neurostimulation.

METHODS

A scoping review of the literature.

RESULTS

In total, 194 articles were included, and findings were presented to highlight emerging principles related to multifidus dysfunction and restorative neurostimulation. Multifidus dysfunction is diagnosed by a history of mechanical, axial, nociceptive CLBP and exam demonstrating functional lumbar instability, which differs from other structural etiologies. Diagnostic images may be used to grade multifidus atrophy and assess other structural pathologies. While various treatments exist for CLBP, restorative neurostimulation distinguishes itself from traditional neurostimulation in a way that treats a different etiology, targets a different anatomical site, and has a distinctive mechanism of action.

CONCLUSIONS

Multifidus dysfunction has been proposed to result from loss of neuromuscular control, which may manifest clinically as muscle inhibition resulting in altered movement patterns. Over time, this cycle may result in potential atrophy, degeneration and CLBP. Restorative neurostimulation, a novel implantable neurostimulator system, stimulates the efferent lumbar medial branch nerve to elicit repetitive multifidus contractions. This intervention aims to interrupt the cycle of dysfunction and normalize multifidus activity incrementally, potentially restoring neuromuscular control. Restorative neurostimulation has been shown to reduce pain and disability in CLBP, improve quality of life and reduce health care expenditures.

International Society for the Advancement of Spine Surgery Statement: Restorative Neurostimulation for Chronic Mechanical Low Back Pain Resulting From Neuromuscular Instability

This International Society for the Advancement of Spine Surgery statement has been generated to respond to growing requests for background, supporting literature and evidence, and proper coding for restorative neurostimulation for chronic low back pain. Chronic low back pain describes the diverse experience of a significant proportion of the population. Conservative management of these patients remains the predominant care pathway, but for many patients, symptom relief is poor. The application of new techniques in patients who have exhausted traditional care paradigms should be undertaken with a detailed understanding of the pathology being treated, the mechanisms involved, and the data supporting efficacy. This statement on restorative neurostimulation places this technology in the context of the current understanding of the etiology of mechanical low back pain and the currently available evidence for this technique. In an appropriately selected cohort with a specific subset of chronic low back pain symptoms, this technique may provide benefit to payers and patients.

Analysis of Degenerative and Isthmic Lumbar Spondylolisthesis from the Difference of Pelvic Parameters and the Degree of Degeneration through Imaging Data

BACKGROUND

In previous studies, many imaging analyses have been conducted to explore the changes in the intervertebral disc degeneration (DD), facet joint osteoarthritis (FJOA), L4 inclination angle (L4IA), pelvis-related parameters, lumbar lordosis (LL), and paravertebral muscle (PVM) in the occurrence and development of degenerative spinal diseases via measuring the X-ray, CT, and MRI data of clinical patients. However, few studies have quantitatively investigated the pelvic parameters and the degree of spine degeneration in patients with degenerative lumbar spondylolisthesis (DLS) and isthmic lumbar spondylolisthesis (ILS). This study discusses the changes in the imaging parameters of DLS, ILS, and a control group; explores the correlation between different measurement parameters; and discusses their risk factors.

METHODS

We evaluated 164 patients with single L4-L5 grade 1 level degenerative lumbar spondylolisthesis (DLS group), 161 patients with single L4-L5 grade 1 level isthmic lumbar spondylolisthesis (ILS group), and 164 patients with non-specific back pain (control group). The grades of DD and FJOA as well as the percentage of the fat infiltration area (%FIA) of multifidus muscle (MM) at the L4-L5 level were measured via CT and MRI. Lumbar lordosis (LL), pelvic incidence (PI), pelvic tilt (PT), the L4 inclination angle (L4IA), and sacral slope (SS) were measured via X-ray film, and the differences among the DLS group, ILS group, and control group were analyzed. Furthermore, the risk factors related to the incidences of the DLS and ILS groups were discussed.

RESULTS

First, the pelvis-related parameters of DLS and ILS patients were 51.91 ± 12.23 and 53.28 ± 11.12, respectively, while those of the control group were 40.13 ± 8.72 (p1 < 0.001, p2 < 0.001). Lumbar lordosis (LL) in DLS patients (39.34 ± 8.57) was significantly lower than in the control group (44.40 ± 11.79, p < 0.001). On the contrary, lumbar lordosis (LL) in the ILS group (55.16 ± 12.31) was significantly higher than in the control group (44.40 ± 11.79, p < 0.001). Secondly, the three groups of patients were characterized by significant variations in the L4 inclination angle (L4IA), disc degeneration (DD), facet joint osteoarthritis (FJOA), pelvis-related parameters, and paravertebral muscle (PVM) (p < 0.05). Finally, logistic regression suggests that the L4IA, FJOA, and PT may be risk factors for the occurrence of DLS, and the occurrence of ILS is correlated with the L4IA, FJOA, DD, PT, and LL.

CONCLUSIONS

Compared with the control group, there are changes in pelvic parameters, the L4IA, LL, DD, FJOA, and PVM in DLS and ILS patients, and the degree is different. The parameters within the same group are related to each other, and DLS and ILS have different risk factors. The mechanical stability of the spine is affected by the parameter and angle changes, which may be of great significance for explaining the cause of spondylolisthesis, evaluating the health of the lumbar spine, and guiding the lifestyles of patients.

ReActiv8 Stimulation Therapy vs. Optimal Medical Management: A Randomized Controlled Trial for the Treatment of Intractable Mechanical Chronic Low Back Pain (RESTORE Trial Protocol)

INTRODUCTION

Chronic low back pain (CLBP) is the leading cause of years lived with disability globally. The role of restorative neurostimulation in the treatment of patients with refractory mechanical CLBP and multifidus muscle dysfunction has been established in one randomized controlled trial (RCT) and several clinical studies that demonstrated both safety and clinical benefit. This post-market trial provides a direct comparison to optimized medical management to test the hypothesis that the addition of restorative neurostimulation to current care paradigms results in significant improvements in back pain-related disability.

METHODS AND ANALYSIS

This trial will include people who have reported significant levels of back pain and back pain-related disability with symptoms that have persisted for longer than 6 months prior to enrollment and resulted in pain on most days in the 12 months prior to enrollment. Eligible patients will be randomized to either optimal medical management or optimal medical management plus ReActiv8® restorative neurostimulation therapy. Patient-reported outcomes will be collected at regular intervals out to the 1-year primary endpoint, at which time the patients in the control arm will be offered implantation with the ReActiv8 system. Assessment of each group will continue for an additional year.

ETHICS AND DISSEMINATION

The RESTORE trial follows the principles of the Declaration of Helsinki. The WCG IRB acts as the Central Institutional Review Board (IRB) for most sites and some sites will receive local IRB approval prior to enrollment of patients. Each IRB assessed the protocol and related documentation. The protocol complies with Good Clinical Practice (GCP). All patients provide written informed consent to participate in the trial.

PROTOCOL VERSION

Version C, 07 Sep 2022.

CLINICALTRIALS

gov registration number. NCT04803214 registered March 17, 2021.

Best Practices for Dorsal Root Ganglion Stimulation for Chronic Pain: Guidelines from the American Society of Pain and Neuroscience

With continued innovations in neuromodulation comes the need for evolving reviews of best practices. Dorsal root ganglion stimulation (DRG-S) has significantly improved the treatment of complex regional pain syndrome (CRPS), and it has broad applicability across a wide range of other conditions. Through funding and organizational leadership by the American Society for Pain and Neuroscience (ASPN), this best practices consensus document has been developed for the selection, implantation, and use of DRG stimulation for the treatment of chronic pain syndromes. This document is composed of a comprehensive narrative literature review that has been performed regarding the role of the DRG in chronic pain and the clinical evidence for DRG-S as a treatment for multiple pain etiologies. Best practice recommendations encompass safety management, implantation techniques, and mitigation of the potential complications reported in the literature. Looking to the future of neuromodulation, DRG-S holds promise as a robust intervention for otherwise intractable pain.

Three-Year Durability of Restorative Neurostimulation Effectiveness in Patients With Chronic Low Back Pain and Multifidus Muscle Dysfunction

BACKGROUND

Restorative neurostimulation is a rehabilitative treatment for patients with refractory chronic low back pain (CLBP) associated with dysfunction of the lumbar multifidus muscle resulting in impaired neuromuscular control. The ReActiv8-B randomized, sham-controlled trial provided evidence of the effectiveness and safety of an implanted, restorative neurostimulator. The two-year analysis previously published in this journal demonstrated accrual of clinical benefits and long-term durability.

OBJECTIVE

Evaluation of three-year effectiveness and safety in patients with refractory, disabling CLBP secondary to multifidus muscle dysfunction and no indications for spine surgery.

MATERIALS AND METHODS

Prospective, observational follow-up of the 204 implanted trial participants. Low back pain visual analog scale (VAS), Oswestry Disability Index (ODI), EuroQol quality of life survey, and opioid intake were assessed at baseline, six months, and one, two, and three years after activation. The mixed-effects model repeated measures approach was used to provide implicit imputations of missing data for continuous outcomes and multiple imputation for proportion estimates.

RESULTS

Data were collected from 133 participants, and 16 patients missed their three-year follow-up because of coronavirus disease restrictions but remain available for future follow-up. A total of 62% of participants had a ≥ 70% VAS reduction, and 67% reported CLBP resolution (VAS ≤ 2.5cm); 63% had a reduction in ODI of ≥ 20 points; 83% had improvements of ≥ 50% in VAS and/or ≥ 20 points in ODI, and 56% had these substantial improvements in both VAS and ODI. A total of 71% (36/51) participants on opioids at baseline had voluntarily discontinued (49%) or reduced (22%) opioid intake. The attenuation of effectiveness in the imputed (N = 204) analyses was relatively small and did not affect the statistical significance and clinical relevance of these results. The safety profile remains favorable, and no lead migrations have been observed to date.

CONCLUSION

At three years, 83% of participants experienced clinically substantial improvements in pain, disability, or both. The results confirm the long-term effectiveness, durability, and safety of restorative neurostimulation in patients with disabling CLBP associated with multifidus muscle dysfunction.

CLINICAL TRIAL REGISTRATION

The Clinicaltrials.gov registration number for the study is NCT02577354.

Long-Term Outcomes of Restorative Neurostimulation in Patients With Refractory Chronic Low Back Pain Secondary to Multifidus Dysfunction: Two-Year Results of the ReActiv8-B Pivotal Trial

BACKGROUND

Impaired neuromuscular control and degeneration of the multifidus muscle have been linked to the development of refractory chronic low back pain (CLBP). An implantable restorative-neurostimulator system can override the underlying multifidus inhibition by eliciting episodic, isolated contractions. The ReActiv8-B randomized, active-sham-controlled trial provided effectiveness and safety evidence for this system, and all participants received therapeutic stimulation from four months onward.

OBJECTIVE

This study aimed to evaluate the two-year effectiveness of this restorative neurostimulator in patients with disabling CLBP secondary to multifidus muscle dysfunction and no indications for spine surgery.

MATERIALS AND METHODS

Open-label follow-up of 204 participants implanted with a restorative neurostimulation system (ReActiv8, Mainstay Medical, Dublin, Ireland) was performed. Pain intensity (visual analog scale [VAS]), disability (Oswestry disability index [ODI]), quality-of-life (EQ-5D-5L), and opioid intake were assessed at baseline, six months, one year, and two years after activation.

RESULTS

At two years (n = 156), the proportion of participants with ≥50% CLBP relief was 71%, and 65% reported CLBP resolution (VAS ≤ 2.5 cm); 61% had a reduction in ODI of ≥20 points, 76% had improvements of ≥50% in VAS and/or ≥20 points in ODI, and 56% had these substantial improvements in both VAS and ODI. A total of 87% of participants had continued device use during the second year for a median of 43% of the maximum duration, and 60% (34 of 57) had voluntarily discontinued (39%) or reduced (21%) opioid intake.

CONCLUSIONS

At two years, 76% of participants experienced substantial, clinically meaningful improvements in pain, disability, or both. These results provide evidence of long-term effectiveness and durability of restorative neurostimulation in patients with disabling CLBP, secondary to multifidus muscle dysfunction.

CLINICAL TRIAL REGISTRATION

The study is registered on clinicaltrials.gov with identifier NCT02577354.

The American Society of Pain and Neuroscience (ASPN) Evidence-Based Clinical Guideline of Interventional Treatments for Low Back Pain

Introduction

Painful lumbar spinal disorders represent a leading cause of disability in the US and worldwide. Interventional treatments for lumbar disorders are an effective treatment for the pain and disability from low back pain. Although many established and emerging interventional procedures are currently available, there exists a need for a defined guideline for their appropriateness, effectiveness, and safety.

Objective

The ASPN Back Guideline was developed to provide clinicians the most comprehensive review of interventional treatments for lower back disorders. Clinicians should utilize the ASPN Back Guideline to evaluate the quality of the literature, safety, and efficacy of interventional treatments for lower back disorders.

Methods

The American Society of Pain and Neuroscience (ASPN) identified an educational need for a comprehensive clinical guideline to provide evidence-based recommendations. Experts from the fields of Anesthesiology, Physiatry, Neurology, Neurosurgery, Radiology, and Pain Psychology developed the ASPN Back Guideline. The world literature in English was searched using Medline, EMBASE, Cochrane CENTRAL, BioMed Central, Web of Science, Google Scholar, PubMed, Current Contents Connect, Scopus, and meeting abstracts to identify and compile the evidence (per section) for back-related pain. Search words were selected based upon the section represented. Identified peer-reviewed literature was critiqued using United States Preventive Services Task Force (USPSTF) criteria and consensus points are presented.

Results

After a comprehensive review and analysis of the available evidence, the ASPN Back Guideline group was able to rate the literature and provide therapy grades to each of the most commonly available interventional treatments for low back pain.

Conclusion

The ASPN Back Guideline represents the first comprehensive analysis and grading of the existing and emerging interventional treatments available for low back pain. This will be a living document which will be periodically updated to the current standard of care based on the available evidence within peer-reviewed literature.

Restorative Neurostimulation: A Clinical Guide for Therapy Adoption

In this review, we present a comprehensive clinical approach to restorative neurostimulation, a novel form of stimulation for refractory chronic mechanical low back pain, targeting impaired neuromuscular control and degeneration of the multifidus muscle. We focus on patient identification, technique guidance, and review of the scientific background and clinical evidence. As our understanding of back pain grows, there is clear evidence that impaired neuromuscular control and consequent degeneration of the multifidus muscle contribute to mechanical low back pain development and maintenance. We provide clinical guidance regarding an implantable restorative neurostimulation system that targets impaired neuromuscular control. Supported by results from a randomized, active-sham-controlled clinical trial with long-term follow-up, we provide clinicians with a comprehensive overview and practical clinical guidance for the adoption of this therapy modality.

Clinical utility and reproducibility of surface electromyography in individuals with chronic low back pain: a protocol for a systematic review and meta-analysis

INTRODUCTION

Chronic low back pain (CLBP) is one of the most common disorders presenting in primary healthcare. Kinematic studies of low lumbar pelvic mobility allied with surface electromyography (sEMG) may assist in the assessment and management of CLBP. However, the applicability in the use of sEMG in the clinical setting remains uncertain. In this protocol, we aim to review the clinical utility and reproducibility of the sEMG component of these kinematic studies in patients with CLBP.

METHODS AND ANALYSIS

This protocol was informed by the Preferred Reporting Items for Systematic review and Meta-Analysis Protocols (PRISMA-P) and results will be reported in line with the PRISMA. Searches will be conducted on PubMed, Scopus, Web of Science, Embase, CINAHL and Google Scholar databases, along with a comprehensive review of grey literature. Two reviewers will conduct the searches and independently screen them, according to title and abstract. Two independent reviewers will then assess the full-text versions of those selected articles and assess the risk of bias using the defined protocol inclusion criteria. The risk of bias within the studies included will be assessed via the Quality Assessment of Diagnostic Accuracy Studies tool, V.2 and the Grading of Recommendations Assessment, Development and Evaluation guidelines will be used to assess certainty of evidence for recommendations based on the risk of bias findings. Meta-analysis will be conducted where appropriate on groups of studies with low heterogeneity. In instances of higher heterogeneity, meta-synthesis will instead be completed, comparing results in terms of increased or decreased clinical utility and/or reproducibility of sEMG.

ETHICS AND DISSEMINATION

Ethics approval was not required for this research. It is anticipated that the results will influence the use, interpretation and further development of sEMG in management and assessment of these patients.

PROSPERO REGISTRATION NUMBER

CRD42021273936.

Non-Spinal Neuromodulation of the Lumbar Medial Branch Nerve for Chronic Axial Low Back Pain: A Narrative Review

Chronic low back pain remains highly prevalent, costly, and the leading cause of disability worldwide. Symptoms are complex and treatment involves an interdisciplinary approach. Due to diverse anatomical etiologies, treatment outcomes with interventional options are highly variable. A novel approach to treating chronic axial low back pain entails the use of peripheral nerve stimulation to the lumbar medial branch nerve, and this review examines the clinical data of the two different, commercially available, non-spinal neuromodulation systems. This review provides the clinician a succinct narrative that presents up-to-date data objectively. Our review found ten clinical studies, including one report of two cases, six prospective studies, and three randomized clinical trials published to date. Currently, there are different proposed mechanisms of action to address chronic axial low back pain with different implantation techniques. Evidence suggests that peripheral nerve stimulation of the lumbar medial branch nerve may be effective in improving pain and function in patients with chronic axial low back pain symptoms at short and long term follow up, with good safety profiles. Further long-term data is needed to consider this intervention earlier in the pain treatment algorithm, but initial data are promising.

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.

Restorative Neurostimulation for Chronic Mechanical Low Back Pain: Results from a Prospective Multi-centre Longitudinal Cohort

INTRODUCTION

Low back pain impacts most people throughout the course of their lives and contributes significantly to the global burden of disease. In some patients, symptoms resolve with little intervention, while others are amenable to surgical intervention, some cases are intractable to current care paradigms. Restorative neurostimulation is an emerging therapy for chronic mechanical low back pain.

METHODS

We conducted a prospective post-market follow-up of 42 patients treated for longstanding chronic mechanical low back pain with restorative neurostimulation. Patients were followed up at 45, 90, and 180 days and 1 and 2 years following activation of the device. Pain, disability, and health-related quality of life were recorded.

RESULTS

Among the 37 patients completing 2-year follow-up, numerical rating scale (NRS) pain scores improved from 7.0 ± 0.2 to 3.5 ± 0.3 (p < 0.001), Oswestry Disability Index (ODI) scores improved from 46.2 ± 2.2 to 29.2 ± 3.1 (p < 0.001), and health-related quality of life (measured by the EuroQol 5-Dimension 5-Level questionnaire-EQ-5D-5L) improved from 0.426 ± 0.035 to 0.675 ± 0.030 (p < 0.001). Additionally, 57% of patients experienced a greater than 50% reduction in pain, and 51% of patients benefited by a greater than 15-point reduction in ODI, both substantial improvements.

CONCLUSION

This real-world sample of patients shows that restorative neurostimulation can provide substantial and durable benefit to a cohort of patients that have traditionally had few reliable treatment options. Our findings support the continued used of this therapy in well-selected patients.

TRIAL REGISTRATION

ClinicalTrials.gov Identifier: NCT01985230.

Updates on the Role of Spinal Cord Stimulation in the Management of Non-Surgical Chronic Lower Back Pain

Studies have shown that spinal cord stimulation (SCS) therapy is effective in the management of chronic low back pain. It plays a role by minimizing the intensity of chronic pain, improving the quality of life index, reducing the intake of narcotic analgesics, and increasing the functional improvement in the working environment. However, spinal cord stimulation therapy is not universal because of the complications in the procedure itself, the invasive nature of the treatment, and cost-effectiveness. Therefore, the proper selection of the patients is necessary to get the maximum benefit from the treatment. The study's main objective is to determine the role of spinal cord stimulation in treating non-surgical patients with chronic low back pain. The article will review the mechanism, outcomes, efficacy, predisposing factors in the success and failure of the treatment and indications, contraindications, and selection of patients undergoing spinal cord stimulation therapy. A manual search of the literature was done using databases like Google Scholar and PubMed using the keywords: spinal cord, stimulation, chronic, and low back pain. A total of 37 articles were included in the study after considering the inclusion and exclusion criteria. Spinal cord stimulation therapy effectively treats refractory lower back pain, considering the technology and mechanism of action. The authors conclude that spinal cord stimulation therapy can be used to manage chronic low back pain, other neuropathic pain, and ischemic pain when other standard treatment methods have failed and the pain persisted for more than six months.

The Added Value of Subcutaneous Peripheral Nerve Field Stimulation Combined with SCS, as Salvage Therapy, for Refractory Low Back Pain Component in Persistent Spinal Pain Syndrome Implanted Patients: A Randomized Controlled Study (CUMPNS Study) Based on 3D-Mapping Composite Pain Assessment

While Spinal Cord Stimulation (SCS) provides satisfaction to almost 2/3 of Persistent Spinal Pain Syndrome-Type 2 (PSPS-T2) patients implanted for refractory chronic back and/or leg pain, when not adequately addressed the back pain component, leaves patients in a therapeutic cul-de-sac. Peripheral Nerve field Stimulation (PNfS) has shown interesting results addressing back pain in the same population. Far from placing these two techniques in opposition, we suggest that these approaches could be combined to better treat PSPS-T2 patients. We designed a RCT (CUMPNS), with a 12-month follow-up, to assess the potential added value of PNfS, as a salvage therapy, in PSPS-T2 patients experiencing a "Failed SCS Syndrome" in the back pain component. Fourteen patients were included in this study and randomized into 2 groups ("SCS + PNfS" group/n = 6 vs. "SCS only" group/n = 8). The primary objective of the study was to compare the percentage of back pain surface decrease after 3 months, using a computerized interface to obtain quantitative pain mappings, combined with multi-dimensional SCS outcomes. Back pain surface decreased significantly greater for the "SCS + PNfS" group (80.2% ± 21.3%) compared to the "SCS only" group (13.2% ± 94.8%) (p = 0.012), highlighting the clinical interest of SCS + PNfS, in cases where SCS fails to address back pain.

An implantable restorative-neurostimulator for refractory mechanical chronic low back pain: a randomized sham-controlled clinical trial

ABSTRACT

Chronic low back pain can be caused by impaired control and degeneration of the multifidus muscles and consequent functional instability of the lumbar spine. Available treatment options have limited effectiveness and prognosis is unfavorable. We conducted an international randomized, double-blind, sham-controlled trial at 26 multidisciplinary centers to determine safety and efficacy of an implantable, restorative neurostimulator designed to restore multifidus neuromuscular control and facilitate relief of symptoms (clinicaltrials.gov identifier: NCT02577354). Two hundred four eligible participants with refractory mechanical (musculoskeletal) chronic LBP and a positive prone instability test indicating impaired multifidus control were implanted and randomized to therapeutic (N = 102) or low-level sham (N = 102) stimulation of the medial branch of the dorsal ramus nerve (multifidus nerve supply) for 30 minutes twice daily. The primary endpoint was the comparison of responder proportions (≥30% relief on the LBP visual analogue scale without analgesics increase) at 120 days. After the primary endpoint assessment, participants in the sham-control group switched to therapeutic stimulation and the combined cohort was assessed through 1 year for long-term outcomes and adverse events. The primary endpoint was inconclusive in terms of treatment superiority (57.1% vs 46.6%; difference: 10.4%; 95% confidence interval, -3.3% to 24.1%, P = 0.138). Prespecified secondary outcomes and analyses were consistent with a modest but clinically meaningful treatment benefit at 120 days. Improvements from baseline, which continued to accrue in all outcome measures after conclusion of the double-blind phase, were clinically important at 1 year. The incidence of serious procedure- or device-related adverse events (3.9%) compared favorably with other neuromodulation therapies for chronic pain.

Understanding the role of patient preference in the treatment algorithm for chronic low back pain: results from a survey-based study

Aims: Interventional pain treatments range from injections to established radiofrequency ablation techniques and finally neuromodulation. In addition to safety, efficacy and cost dominance, patient preference for type of treatment is important. Methods: Chronic pain patients (n = 129) completed a preference scale to determine which interventional pain management procedures they would prefer from among radiofrequency ablation, temporary (60-day) peripheral nerve stimulation (PNS), conventional PNS and spinal cord stimulation/dorsal root ganglion stimulation. A second survey (n = 347) specific to assessing the preference for radiofrequency ablation or temporary PNS treatment was completed by patients with low back pain. Results: On the basis of mean rank, temporary PNS percutaneously implanted for up to 60 days was the most preferred treatment compared with the other options presented (p = 0.002). Conclusions: Patient preference should be unbiased and considered as an independent variable for physician discussion in treatment options and future research.

A Paramedian Approach for Dorsal Root Ganglion Stimulation Placement Developed to Limit Lead Migration and Fracture

INTRODUCTION

Dorsal root ganglion stimulation (DRG-S), has demonstrated superiority in the treatment of complex regional pain syndrome and causalgia. Lead migration and fracture impact DRG-S therapeutic stability. Lead anchoring reduces DRG-S lead migration without increasing lead fracture. Lead fracture may be related to lead entrapment in the superficial fascial plane. A novel medialized approach for lead placement and anchoring is presented to address these issues.

METHODS

We suggest an alternative technique for implanting percutaneous DRG-S leads at the T10-L5 levels.

RESULTS

A novel medialized ipsilateral technique for lead placement and anchoring for single, bilateral, and adjacent segment placement is presented. The Tuohy needle puncture site is medial to the pedicle and adjacent to the spinous process, two vertebral levels caudad to the target foramen. Trajectory is maintained in the sagittal plane, to access the caudad interlaminar space near the midline. This technique allows for ipsilateral or contralateral lead placement. After epidural access, the introducer sheath is rotated toward the targeted foramen and advanced. The guidewire followed by the lead is passed, and once lead position is confirmed, tension 'S' loops are created, followed by anchoring to the deep fascia.

CONCLUSION

We describe a new paramedian technique for DRG-S lead placement. We propose it will decrease DRG-S complication rates through anchoring to reduce migration and by avoiding the fascial planes thought to be responsible for fracture. Long-term outcomes applying our proposed techniques are required for determining the true impact, however, early anecdotal results suggest that these new techniques are favorable.

New Advances in Neurostimulation for Chronic Pain

Around 50 million people in the United States live with-and suffer from-chronic pain. While some pain patients receive relief from physical therapy, medication, or surgery, others aren't helped by these treatments. "It's a debilitating situation," says Ryan Lakin, divisional vice president of R&D at Abbott. "Patients have trouble just living a normal life, doing a lot of things that we take for granted."

Durability of the Therapeutic Effect of Restorative Neurostimulation for Refractory Chronic Low Back Pain

Objectives

The purpose of the ongoing follow‐up of ReActiv8‐A clinical trial is to document the longitudinal benefits of episodic stimulation of the dorsal ramus medial branch and consequent contraction of the lumbar multifidus in patients with refractory mechanical chronic low back pain (CLBP). We report the four‐year outcomes of this trial.

Materials and Methods

ReActiv8‐A is a prospective, single‐arm trial performed at nine sites in the United Kingdom, Belgium, and Australia. Eligible patients had disabling CLBP (low back pain Numeric Rating Scale [NRS] ≥6; Oswestry Disability Index [ODI] ≥25), no indications for spine surgery or spinal cord stimulation, and failed conventional management including at least physical therapy and medications for low back pain. Fourteen days postimplantation, stimulation parameters were programmed to elicit strong, smooth contractions of the multifidus, and participants were given instructions to activate the device for 30‐min stimulation‐sessions twice daily. Annual follow‐up through four years included collection of NRS, ODI, and European Quality of Life Score on Five Dimensions (EQ‐5D). Background on mechanisms, trial design, and one‐year outcomes were previously described.

Results

At baseline (N = 53) (mean ± SD) age was 44 ± 10 years; duration of back pain was 14 ± 11 years, NRS was 6.8 ± 0.8, ODI 44.9 ± 10.1, and EQ‐5D 0.434 ± 0.185. Mean improvements from baseline were statistically significant (p < 0.001) and clinically meaningful for all follow‐ups. Patients completing year 4 follow‐up, reported mean (±standard error of the mean) NRS: 3.2 ± 0.4, ODI: 23.0 ± 3.2, and EQ‐5D: 0.721 ± 0.035. Moreover, 73% of participants had a clinically meaningful improvement of ≥2 points on NRS, 76% of ≥10 points on ODI, and 62.5% had a clinically meaningful improvement in both NRS and ODI and 97% were (very) satisfied with treatment.

Conclusions

In participants with disabling intractable CLBP who receive long‐term restorative neurostimulation, treatment satisfaction remains high and improvements in pain, disability, and quality‐of‐life are clinically meaningful and durable through four years.

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.

Mechanism of Action of Peripheral Nerve Stimulation

PURPOSE OF REVIEW

The number of applications for peripheral nerve stimulation (PNS) in the pain management field is ever-growing. With the increasing number of clinical applications for peripheral nerve stimulation, the purpose of this article is to review the mechanism of action surrounding PNS, the recent literature from January 2018 to January 2021, and pertinent clinical outcomes.

RECENT FINDINGS

The authors searched articles identified from PubMed (January 2018-January 2021), Cochrane Central Register of Controlled Trials databases (January 2018-January 2021), and Scopus (January 2018-January 2021) databases, and manually searched references of identified publications. Broad MeSH terms and Boolean operators were queried in each search, including the following terms and their respective synonyms: peripheral nerve stimulation, mechanism of action, biochemical pathway, and pain pathway. 15 consensus articles were selected for in-depth review and inclusion for qualitative analysis. PNS may activate and modulate higher central nervous system (CNS) centers, including the dorsal lateral prefrontal cortex, somatosensory cortex, anterior cingulate cortex, and parahippocampal areas. Neuromodulatory effects from PNS may also extend into the spinal columns. Also, PNS may lead to changes in endogenous neurotransmitters and affect the plasticity of NMDA pathways.

Slacklining as therapy to address non-specific low back pain in the presence of multifidus arthrogenic muscle inhibition

Low back pain (LBP) represents the most prevalent, problematic and painful of musculoskeletal conditions that affects both the individual and society with health and economic concerns. LBP is a heterogeneous condition with multiple diagnoses and causes. In the absence of consensus definitions, partly because of terminology inconsistency, it is further referred to as non-specific LBP (NSLBP). In NSLBP patients, the lumbar multifidus (MF), a key stabilizing muscle, has a depleted role due to recognized myocellular lipid infiltration and wasting, with the potential primary cause hypothesized as arthrogenic muscle inhibition (AMI). This link between AMI and NSLBP continues to gain increasing recognition. To date there is no 'gold standard' or consensus treatment to alleviate symptoms and disability due to NSLBP, though the advocated interventions are numerous, with marked variations in costs and levels of supportive evidence. However, there is consensus that NSLBP management be cost-effective, self-administered, educational, exercise-based, and use multi-modal and multi-disciplinary approaches. An adjuvant therapy fulfilling these consensus criteria is 'slacklining', within an overall rehabilitation program. Slacklining, the neuromechanical action of balance retention on a tightened band, induces strategic indirect-involuntary therapeutic muscle activation exercise incorporating spinal motor control. Though several models have been proposed, understanding slacklining's neuro-motor mechanism of action remains incomplete. Slacklining has demonstrated clinical effects to overcome AMI in peripheral joints, particularly the knee, and is reported in clinical case-studies as showing promising results in reducing NSLBP related to MF deficiency induced through AMI (MF-AMI). Therefore, this paper aims to: rationalize why and how adjuvant, slacklining therapeutic exercise may positively affect patients with NSLBP, due to MF-AMI induced depletion of spinal stabilization; considers current understandings and interventions for NSLBP, including the contributing role of MF-AMI; and details the reasons why slacklining could be considered as a potential adjuvant intervention for NSLBP through its indirect-involuntary action. This action is hypothesized to occur through an over-ride or inhibition of central down-regulatory induced muscle insufficiency, present due to AMI. This subsequently allows neuroplasticity, normal neuro-motor sequencing and muscle re-activation, which facilitates innate advantageous spinal stabilization. This in-turn addresses and reduces NSLBP, its concurrent symptoms and functional disability. This process is hypothesized to occur through four neuro-physiological processing pathways: finite neural delay; movement-control phenotypes; inhibition of action and the innate primordial imperative; and accentuated corticospinal drive. Further research is recommended to investigate these hypotheses and the effect of slacklining as an adjuvant therapy in cohort and control studies of NSLBP populations.

Development and Description of a New Multifidus-Sparing Radiofrequency Neurotomy Technique for Facet Joint Pain

INTRODUCTION

The technique of radiofrequency neurotomy (RFN) of the facet joints has been used for decades to treat persistent low back pain to good effect in carefully selected patients. Traditionally, the target is the medial branches of the dorsal root supplying the facet joint. An alternative denervation target is the facet joint capsule. Capsule-targeting techniques may spare the multifidus muscle, a possible unintended target of traditional RFN that is thought to be important in recovering from low back pain, and have shown promising results.

METHODS

A modified RFN technique that targets the capsule and spares the multifidus (multifidus-sparing RFN) is described here, along with a brief report of its application in patients with symptomatic facet joint low back pain as compared to traditional medial branch RFN (MBRF).

RESULTS

Over a 2-year period, a total of 401 initial multifidus-sparing RFN and 94 initial MBRF procedures were performed on patients attending a multidisciplinary pain clinic. The proportion of repeat procedures was similar: 28.4% of multifidus-sparing procedures and 23.4% of MBRF procedures. The median repeat interval was 12 months for both groups and interquartile range was 10 months (8-18 months) for multifidus-sparing RFN and 4 months (11-15 months) for MBRF. Effectiveness and safety profiles appear to be similar, although limited, retrospective outcome information prevented robust analysis.

CONCLUSION

Multifidus-sparing RFN represents an intriguing technique to denervate the facet joint pain generator while maintaining normal multifidus function. Further study is warranted, particularly in order to identify the appropriate patient criteria and long-term outcomes.

Current Perspectives on Neurostimulation for the Management of Chronic Low Back Pain: A Narrative Review

Neurostimulation techniques for the treatment of chronic low back pain (LBP) have been rapidly evolving; however, questions remain as to which modalities provide the most efficacious and durable treatment for intractable axial symptoms. Modalities of spinal cord stimulation, such as traditional low-frequency paresthesia based, high-density or high dose (HD), burst, 10-kHz high-frequency therapy, closed-loop, and differential target multiplexed, have been limitedly studied to determine their efficacy for the treatment of axial LBP. In addition, stimulation methods that target regions other than the spinal cord, such as medial branch nerve stimulation of the multifidus muscles and the dorsal root ganglion may also be viable treatment options. Here, current scientific evidence behind neurostimulation techniques have been reviewed with a focus on the management of chronic axial LBP.

The Politics of Chronic LBP: Can We Rely on a Proxy-Vote? Linking Multifidus Intra-Myo-Cellular Lipid (IMCL) Fatty Infiltration With Arthrogenic Muscle Inhibition (AMI)-induced Chronic Nonspecific Low Back Pain

STUDY DESIGN

Retrospective review of the literature.

OBJECTIVE

To update recent trends in the use of magnetic resonance spectroscopy (MRS) analysis for CLBP.

SUMMARY OF BACKGROUND DATA

The lumbar multifidus (MF) muscle has drawn sustained interest for some time, particularly related to its structure, role in spinal stability, and its association and clinical significance with CLBP. Additionally, the presence of MF-arthrogenic muscle inhibition (AMI) and its relation to induced CLBP, through depleted lumbar stabilization, has gained increased recognition. In contrast, the differential diagnostic use of MRS analysis has suggested specific links between the presence of MF myo-cellular lipid (MCL) infiltration and CLBP patients.

METHODS

Review of the literature related to CLBP with the keywords MCL, MRS analysis, and MF-AMI.

RESULTS

No articles discussed CLBP using the three key concepts in a single context. The use of MRS analysis has the capacity to distinguish between Extra-MCL (EMCL) and intra-MCL (IMCL) infiltration within the lumbar MF. It is suggested that EMCLs are more likely to be associated with age-related change, while the IMCLs appear more likely to be associated with the presence of CLBP. The increased recognition of MF-AMI as a primary cause of CLBP, and the potential that AMI parallels the presence of IMCLs, facilitates possible use of MRS as a means to quantify the basis of lumbar MF-AMI CLBP, and that proportional IMCL changes in the MF could serve as a 'proxy' to indicate the effectiveness of interventions directed at MF activation.

CONCLUSIONS

It may be possible for IMCLs to serve as a 'proxy' prognostic marker of lumbar MF-AMI in CLBP patients. Further, if this assertion were correct, then reductions in IMCLs could potentially quantify recovery and the efficacy of rehabilitation management strategies directed at lumbar MF activation.Level of Evidence: 5.

Transvenous Phrenic Nerve Stimulation for Treatment of Central Sleep Apnea: Five-Year Safety and Efficacy Outcomes

BACKGROUND

The remedē System Pivotal Trial was a prospective, multi-center, randomized trial demonstrating transvenous phrenic nerve stimulation (TPNS) therapy is safe and effectively treats central sleep apnea (CSA) and improves sleep architecture and daytime sleepiness. Subsequently, the remedē System was approved by FDA in 2017. As a condition of approval, the Post Approval Study (PAS) collected clinical evidence regarding long-term safety and effectiveness in adults with moderate to severe CSA through five years post implant.

METHODS

Patients remaining in the Pivotal Trial at the time of FDA approval were invited to enroll in the PAS and consented to undergo sleep studies (scored by a central laboratory), complete the Epworth Sleepiness Scale (ESS) questionnaire to assess daytime sleepiness, and safety assessment. All subjects (treatment and former control group) receiving active therapy were pooled; data from both trials were combined for analysis.

RESULTS

Fifty-three of the original 151 Pivotal Trial patients consented to participate in the PAS and 52 completed the 5-year visit. Following TPNS therapy, the apnea-hypopnea index (AHI), central-apnea index (CAI), arousal index, oxygen desaturation index, and sleep architecture showed sustained improvements. Comparing 5 years to baseline, AHI and CAI decreased significantly (AHI baseline median 46 events/hour vs 17 at 5 years; CAI baseline median 23 events/hour vs 1 at 5 years), though residual hypopneas were present. In parallel, the arousal index, oxygen desaturation index and sleep architecture improved. The ESS improved by a statistically significant median reduction of 3 points at 5 years. Serious adverse events related to implant procedure, device or delivered therapy were reported by 14% of patients which include 16 (9%) patients who underwent a pulse generator reposition or lead revision (primarily in the first year). None of the events caused long-term harm. No unanticipated adverse device effects or related deaths occurred through 5 years.

CONCLUSION

Long-term TPNS safely improves CSA, sleep architecture and daytime sleepiness through 5 years post implant.

CLINICAL TRIAL REGISTRATION

ClinicalTrials.gov Identifier: NCT01816776.

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

PURPOSE

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

MATERIALS AND METHODS

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

RESULTS

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

CONCLUSION

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

A Review of Peripheral Nerve Stimulation Techniques Targeting the Medial Branches of the Lumbar Dorsal Rami in the Treatment of Chronic Low Back Pain

OBJECTIVES

The lumbar medial branch nerve has historically been a focus for ablative techniques in the treatment of chronic low back pain (CLBP) of facetogenic origin. Recent developments in the field of neuromodulation have been employed to target these nerves for analgesia and/or functional restoration in broader populations of CLBP patients. The objective of this article was to provide an introductory review of procedural techniques and devices employed for peripheral nerve stimulation (PNS) of the lumbar medial branch of the dorsal ramus for the treatment of CLBP.

METHODS

A literature search via PubMed.gov was performed through September 2019 with key words focusing on peripheral nerve stimulation for chronic low back pain. This was refined to include only those articles that focused specifically on stimulation of the lumbar medial branch of the dorsal ramus. References within selected articles and unpublished data currently in the peer review process were also utilized.

RESULTS

Ninety articles from PubMed.gov were obtained. Two approaches to PNS of the medial branch of the dorsal ramus were identified.

CONCLUSIONS

Our review of the current literature regarding techniques for neuromodulation of the medial branch of the dorsal ramus revealed two dominant methods: a temporarily implanted percutaneous coiled-lead approach and a permanently implanted system. The two techniques share some similarities, such as targeting the medial branch of the dorsal ramus, and also have some differences, such as indwelling time, stimulation parameters, duration of treatment, image guidance, and degrees of invasiveness, but they are both demonstrating promising results in clinical trials.

A review of the bioelectronic implications of stimulation of the peripheral nervous system for chronic pain conditions

Background

Peripheral Nerve Stimulation has been used to treat human disease including pain for several decades. Innovation has made it a more viable option for treatment of common chronic pain processes, and interest in the therapy is increasing.

Main body

While clinical data is forthcoming, understanding factors that influence successful outcomes in the use of PNS still needs to be delineated. This article reviews the evolution and bioelectronic principles of peripheral nerve stimulation including patient selection, nerve targets, techniques and guidance of target delivery. We collate the current evidence for outcomes and provide recommendations for salient topics in PNS.

Conclusion

Peripheral nerve stimulation has evolved from a surgically invasive procedure to a minimally invasive technique that can be used early in the treatment of peripheral nerve pain. This review identifies and addresses many of the variables which influence the success of PNS in the clinical setting.

The association between pain intensity and disability in patients with failed back surgery syndrome, treated with spinal cord stimulation

OBJECTIVE

Pain researchers demonstrated that pain intensity is not the most reliable measure of the success of chronic-pain treatment. Several research groups have proposed "core outcome domains", such as measurements of disability, to assess the effect of an intervention in pain patients. Up till now, studies investigating the relation between pain intensity and disability in patients treated with spinal cord stimulation (SCS) are lacking. Therefore, the current objective is to examine which pain-reporting strategy, routinely used in pain research, associates best with the degree of disability in these patients.

METHODS

Eighty-one failed back surgery syndrome patients (37 males and 44 females, mean age 54.6 years), treated with high-dose spinal cord stimulation (HD-SCS) are recruited. Pain intensity was scored on an 11-point numerical rating scale (NRS) for leg and back pain, while disability was assessed with the Oswestry disability index (ODI). The association between both variables was investigated with Spearman's correlation and Cramér's V.

RESULTS

Significant correlations (p < 0.001) are found between the absolute and relative differences of the ODI and NRS. Significant associations were found between reported cut-offs in literature (≤3, ≤5, and 50% pain relief) and the degree of disability. Finally, a significant association (p < 0.001) was found between the minimal clinical important difference.

CONCLUSIONS

In this study, we showed that the degree of disability was strongly associated with the pain intensity as measured using different methods. The standard method for reporting pain intensity reduction (50%) seems to associate the strongest with the degree of disability. However, a low degree of disability does not always reflect a low pain intensity.Implications for rehabilitationThe degree of disability reveals a good association with the reporting methods of pain intensity from the literature.The Oswestry disability index could serve as a valid tool to measure the effect of spinal cord stimulation on pain.Disability measures offer a better insight in the clinical profile of chronic pain patients than a pain intensity score.

Transcranial direct current stimulation for nonspecific low back pain: double-blind randomized sham-controlled trial

Introduction: Low back pain is recognized as a major cause of morbidity worldwide. Between 70 and 80% of adults experience at least one occasion of low back pain with duration of 3 months or longer in their lifetime. Aside from the classic treatment methods, there are other new techniques yet to be clinically investigated. Transcranial direct current stimulation (tDCS) has been reported to alleviate pain by affecting the central nervous system. To date only a small number of studies have been published on the effects of tDCS on chronic low back pain. Some of these were pilot studies and others were low-powered in terms of their inference. Therefore the clinical application of tDCS requires further careful evaluation. Objective: To assess the efficacy of transcranial direct current stimulation for treatment of chronic nonspecific low back pain. Materials and methods: We carried out a double-blind randomized sham-controlled trial in a University Hospital. In total 70 people (15 women) with low back pain were randomized to either active or sham stimulation. The primary outcome was intensity of low back pain on the Visual Analog Scale. We also used the Oswestry Disability Questionnaire to evaluate the effects of back pain on daily activities. For the active stimulation group we administered 2 mA tDCS, 20 minutes for each session, once daily, 5 days per week for 2 weeks, totaling 10 sessions. For the sham stimulation group a similar program was followed with no stimulation. Both groups used analgesic medication. Results: Within-group analysis showed that an initial decrease in pain intensity was significant in both groups (both p < 0.001). However, pain reduction became stable only in the active treatment group. There was a significant difference in the pattern of change in mean pain scores in favor of tDCS (p < 0.001). Active treatment also significantly reduced disability scores (all p values < 0.001), whereas participants in the sham treatment group did not experience functional recovery. Mixed ANOVA indicated that the pattern of change in mean scores of disability differed between the two groups throughout the study course, in favor of active stimulation (p < 0.001). Conclusion: Transcranial direct current stimulation is an effective and safe initial treatment for chronic nonspecific low back pain, and the benefits remain for at least several months.

Changes in Spinal and Corticospinal Excitability in Patients with Chronic Ankle Instability: A Systematic Review with Meta-Analysis

The objective of this systematic review with meta-analysis was to determine alterations in spinal and corticospinal excitability of ankle muscles in patients with chronic ankle instability (CAI) compared to uninjured controls. Independent researchers performed comprehensive literature searches of electronic databases and included studies that compared groups with and without CAI and investigated neural excitability with Hoffmann reflex (H-reflex) and/or transcranial magnetic stimulation (TMS). A fixed-effect meta-analysis was conducted to determine group differences for (1) soleus and fibularis maximal H-reflex (Hmax)/maximal M-wave (Mmax)-ratios, and (2) soleus and fibularis longus cortical motor thresholds (CMTs). Seventeen studies were included in the current meta-analysis. They showed that the Hmax/Mmax-ratios of the soleus and the fibularis longus in the CAI group were significantly lower than those in the uninjured control group (soleus: d = −0.41, p < 0.001; fibularis longus: d = −0.27, p = 0.04). There was no evidence for changes in the CMT. This systematic review is the first to demonstrate evidence that patients with CAI present decreased spinal reflex excitability in the soleus and fibularis longus. However, there is no evidence of changes in supraspinal excitability when considering only the CMT. The latter result needs to be interpreted with caution as all except one study demonstrate some changes at the supraspinal level with CAI.

Glucocorticoid injections for greater trochanteric pain syndrome: a randomised double-blind placebo-controlled (GLUTEAL) trial

Small observational studies suggest that local glucocorticoid (GC) injection may be effective in the management of the greater trochanteric pain syndrome (GTPS). The objective was to perform the first randomised double-blind placebo-controlled trial to investigate the efficacy of local GC injection in the management of GTPS. The trial was conducted between November 2011 and May 2015. Inclusion criteria included lateral hip pain (LHP) for greater than 1 month, a LHP score of ≥ 4/10 and typical LHP reproduced by palpation of the greater trochanter. Participants were randomised in a 1:1 ratio to injection with a combination of local anaesthetic and GC (intervention) or injection with normal saline solution (placebo). The primary outcome of interest was the difference in pain intensity at 4 weeks post-injection between the two groups. Patients were followed for 6 months. A total of 46 patients were included. There were no significant differences between the two groups in terms of pain reduction at 1 month (p = 0.23). When including all measures in the first 4 weeks and using multilevel regression, there was a trend towards improvement in pain scores in favour of the intervention group (p = 0.08). There were no significant differences in pain scores between groups at 3 and 6 months. In the management of GTPS, local glucocorticoid injections are of no greater efficacy than injection of normal saline solution. Given the lack of long-term improvement and the potential for cortisone-related side effects, this intervention is of limited benefit.

New Therapy for Refractory Chronic Mechanical Low Back Pain-Restorative Neurostimulation to Activate the Lumbar Multifidus: One Year Results of a Prospective Multicenter Clinical Trial

Objectives

The purpose of the international multicenter prospective single arm clinical trial was to evaluate restorative neurostimulation eliciting episodic contraction of the lumbar multifidus for treatment of chronic mechanical low back pain (CMLBP) in patients who have failed conventional therapy and are not candidates for surgery or spinal cord stimulation (SCS).

Materials and Methods

Fifty‐three subjects were implanted with a neurostimulator (ReActiv8, Mainstay Medical Limited, Dublin, Ireland). Leads were positioned bilaterally with electrodes close to the medial branch of the L2 dorsal ramus nerve. The primary outcome measure was low back pain evaluated on a 10‐Point Numerical Rating Scale (NRS). Responders were defined as subjects with an improvement of at least the Minimal Clinically Important Difference (MCID) of ≥2‐point in low back pain NRS without a clinically meaningful increase in LBP medications at 90 days. Secondary outcome measures included Oswestry Disability Index (ODI) and Quality of Life (QoL; EQ‐5D).

Results

For 53 subjects with an average duration of CLBP of 14 years and average NRS of 7 and for whom no other therapies had provided satisfactory pain relief, the responder rate was 58%. The percentage of subjects at 90 days, six months, and one year with ≥MCID improvement in single day NRS was 63%, 61%, and 57%, respectively. Percentage of subjects with ≥MCID improvement in ODI was 52%, 57%, and 60% while those with ≥MCID improvement in EQ‐5D was 88%, 82%, and 81%. There were no unanticipated adverse events (AEs) or serious AEs related to the device, procedure, or therapy. The initial surgical approach led to a risk of lead fracture, which was mitigated by a modification to the surgical approach.

Conclusions

Electrical stimulation to elicit episodic lumbar multifidus contraction is a new treatment option for CMLBP. Results demonstrate clinically important, statistically significant, and lasting improvement in pain, disability, and QoL.

Muscle Control and Non-specific Chronic Low Back Pain

Objectives

Chronic low back pain (CLBP) is the most prevalent of the painful musculoskeletal conditions. CLBP is a heterogeneous condition with many causes and diagnoses, but there are few established therapies with strong evidence of effectiveness (or cost effectiveness). CLBP for which it is not possible to identify any specific cause is often referred to as non‐specific chronic LBP (NSCLBP). One type of NSCLBP is continuing and recurrent primarily nociceptive CLBP due to vertebral joint overload subsequent to functional instability of the lumbar spine. This condition may occur due to disruption of the motor control system to the key stabilizing muscles in the lumbar spine, particularly the lumbar multifidus muscle (MF).

Methods

This review presents the evidence for MF involvement in CLBP, mechanisms of action of disruption of control of the MF, and options for restoring control of the MF as a treatment for NSCLBP.

Results

Imaging assessment of motor control dysfunction of the MF in individual patients is fraught with difficulty. MRI or ultrasound imaging techniques, while reliable, have limited diagnostic or predictive utility. For some patients, restoration of motor control to the MF with specific exercises can be effective, but population results are not persuasive since most patients are unable to voluntarily contract the MF and may be inhibited from doing so due to arthrogenic muscle inhibition.

Conclusions

Targeting MF control with restorative neurostimulation promises a new treatment option.