Burst Spinal Cord Stimulation for Limb and Back Pain

A Visual and Narrative Timeline Review of Spinal Cord Stimulation Technology and US Food and Drug Administration Milestones

OBJECTIVES

The aim of this study was to present key technologic and regulatory milestones in spinal cord stimulation (SCS) for managing chronic pain on a narrative timeline with visual representation, relying on original sources to the extent possible.

MATERIALS AND METHODS

We identified technical advances in SCS that facilitated and enhanced treatment on the basis of scientific publications and approvals from the United States (US) Food and Drug Administration (FDA). We presented milestones limited to first use in key indications and in the context of new technology validation. We focused primarily on pain management, but other indications (eg, motor disorder in multiple sclerosis) were included when they affected technology development.

RESULTS

We developed a comprehensive visual and narrative timeline of SCS technology and US FDA milestones. Since its conception in the 1960s, the science and technology of SCS neuromodulation have continuously evolved. Advances span lead design (from paddle-type to percutaneous, and increased electrode contacts) and stimulator technology (from wireless power to internally powered and rechargeable, with miniaturized components, and programmable multichannel devices), with expanding stimulation program flexibility (such as burst and kilohertz stimulation frequencies), as well as usage features (such as remote programming and magnetic resonance imaging conditional compatibility).

CONCLUSIONS

This timeline represents the evolution of SCS technology alongside expanding FDA-approved indications for use.

Burst Stimulation Evokes Increased Bladder and Urethral Pressure in Patients With Sacral Neuromodulation, Indicating Potential Activation of the Autonomic Nervous System: A Pilot Study

OBJECTIVES

Currently, sacral neuromodulation (SNM) outcomes are often suboptimal, and changing stimulation parameters might improve SNM efficacy. Burst stimulation mimics physiological burst firing of the nervous system and might therefore benefit patients treated with SNM. The purpose of the present pilot study was to evaluate the effect of various Burst SNM paradigms on bladder and urethral pressure in patients with overactive bladder (OAB) or nonobstructive urinary retention (NOUR).

MATERIALS AND METHODS

The bladder was filled to 50% of its capacity under general anesthesia in six patients with an implanted sacral lead for SNM purposes. Bladder pressure, and mid- and proximal urethral pressure were measured using conventional (Con-) SNM and various Burst SNM paradigms (10-20-40 Hz interburst frequency) with increasing amplitudes up to 5 mA for Con-SNM and 4 mA for Burst SNM.

RESULTS

Burst SNM caused a substantial increase in both bladder and urethral pressure. In contrast, Con-SNM caused a milder increase in urethral pressure, and only one patient showed a modest increase in bladder pressure. Furthermore, the pressure increase was higher in the proximal urethra than in the midurethra using Burst-SNM, whereas Con-SNM caused comparable increases in proximal and midurethra pressure.

CONCLUSIONS

Burst SNM induces bladder contraction compared with Con-SNM and induces higher pressure increases in bladder and proximal urethra than does Con-SNM in patients with OAB or NOUR, indicating a higher degree of autonomic nervous system stimulation. The observed responses could not be fully explained by the total charge of the Burst SNM paradigms, which suggests the importance of individual Burst SNM parameters, such as frequency and amplitude. Future studies should assess the feasibility and efficacy of Burst SNM in awake patients.

Emotional and psychosocial function after dorsal column spinal cord stimulator implantation: a systematic review and meta-analysis

BACKGROUND

The efficacy of spinal cord stimulation (SCS) in chronic pain studies is traditionally assessed by pain scores, which do not reflect the multidimensional nature of pain perception. Despite the evidence of SCS's influence on emotional functioning comprehensive assessments of its effect remain lacking.

OBJECTIVE

To assess changes in emotional and psychosocial functioning in patients who underwent SCS implantation for chronic pain.

EVIDENCE REVIEW

Ovid MEDLINE, EMBASE, PsychINFO, Cochrane CENTRAL and Scopus databases were searched for original peer-reviewed publications reporting emotional functioning after SCS. The primary outcomes were a pooled mean difference (MD) in anxiety, depression, global functioning, mental well-being and pain catastrophizing at 12 months. The Grading of Recommendation, Assessment, Development, and Evaluation (GRADE) was used to determine the quality of evidence.

FINDINGS

Thirty-two studies were included in the primary analysis. Statistically significant improvements were observed in anxiety (MD -2.16; 95% CI -2.84 to -1.49; p<0.001), depression (MD -4.66; 95% CI -6.26 to -3.06; p<0.001), global functioning (MD 20.30; 95% CI 14.69 to 25.90; p<0.001), mental well-being (MD 4.95; 95% CI 3.60 to 6.31; p<0.001), and pain catastrophizing (MD -12.09; 95% CI -14.94 to -9.23; p<0.001). Subgroup analyses revealed differences in Global Assessment of Functioning and mental well-being based on study design and in depression based on waveform paradigm.

CONCLUSION

The results highlight the statistically and clinically significant improvements in emotional and psychosocial outcomes in patients with chronic pain undergoing SCS therapy. However, these results need to be interpreted with caution due to the very low certainty of evidence per the GRADE criteria.

PROSPERO REGISTRATION

CRD42023446326.

Spinal Cord Stimulation for Central Neuropathic Pain After Spinal Cord Injury: A Single-Center Case Series

Purpose

Central neuropathic pain (CNP) following spinal cord injury (SCI) presents a formidable therapeutic challenge, affecting over 50% of the patients post-SCI. For those who experience CNP, conventional treatments often prove insufficient. Spinal cord stimulation (SCS) emerges as a potential intervention for chronic pain after SCI that is unresponsive to pharmacotherapy and supportive measures. However, the efficacy of SCS in alleviating CNP is notably limited. The objective of our study was to evaluate novel stimulation paradigms in SCS for patients with severe CNP after SCI, based on our extensive experience.

Patients and Methods

From a pool of 112 patients treated with SCS for chronic neuropathic pain in the Department of Neurosurgery and Neurology, we selected eight individuals (4 males and 4 females) with CNP for our case series. Burst and high frequency SCS was applied. The assessment involved utilizing the Numeric Rating Scale (NRS), the Neuropathic Pain Symptom Inventory (NPSI), and the EQ-5D quality of life scale before surgery and during a 12-month follow-up period.

Results

Over the course of the one-year follow-up, only two patients experienced satisfactory relief from pain, demonstrating the effectiveness of the stimulation. Moreover, high-frequency and burst SCS failed to show improvement in the remaining six patients.

Conclusion

Our findings suggest that, despite the incorporation of new stimulation paradigms such as burst stimulation and high-frequency stimulation, SCS does not exhibit significant effectiveness in treating neuropathic pain in patients after SCI. These findings highlight the ongoing challenge of treating CNP and emphasize the importance of investigating alternative therapeutic strategies for this group.

The deep and the deeper: Spinal cord and deep brain stimulation for neuropathic pain

Neuropathic pain occurs in people experiencing lesion or disease affecting the somatosensorial system. It is present in 7 % of the general population and may not fully respond to first- and second-line treatments in up to 40 % of cases. Neuromodulation approaches are often proposed for those not tolerating or not responding to usual pharmacological management. These approaches can be delivered surgically (invasively) or non-invasively. Invasive neuromodulation techniques were the first to be employed in neuropathic pain. Among them is spinal cord stimulation (SCS), which consists of the implantation of epidural electrodes over the spinal cord. It is recommended in some guidelines for peripheral neuropathic pain. While recent studies have called into question its efficacy, others have provided promising data, driven by advances in techniques, battery capabilities, programming algorithms and software developments. Deep brain stimulation (DBS) is another well-stablished neuromodulation therapy routinely used for movement disorders; however, its role in pain management remains limited to specific research centers. This is not only due to variable results in the literature contesting its efficacy, but also because several different brain targets have been explored in small trials, compromising comparisons between these studies. Structures such as the periaqueductal grey, posterior thalamus, anterior cingulate cortex, ventral striatum/anterior limb of the internal capsule and the insula are the main targets described to date in literature. SCS and DBS present diverse rationales for use, mechanistic backgrounds, and varying levels of support from experimental studies. The present review aims to present their methodological details, main mechanisms of action for analgesia and their place in the current body of evidence in the management of patients with neuropathic pain, as well their particularities, effectiveness, safety and limitations.

EEG-Based Cortical Alterations in Individuals With Chronic Knee Pain Secondary to Osteoarthritis: A Cross-sectional Investigation

Chronic painful knee osteoarthritis (OA) is a disabling physical health condition. Alterations in brain responses to arthritic changes in the knee may explain persistent pain. This study investigated source localized, resting-state electroencephalography activity and functional connectivity in people with knee OA, compared to healthy controls. Adults aged 44 to 85 years with knee OA (n = 37) and healthy control (n = 39) were recruited. Resting-state electroencephalography was collected for 10 minutes and decomposed into infraslow frequency (ISF) to gamma frequency bands. Standard low-resolution electromagnetic brain tomography statistical nonparametric maps were conducted, current densities of regions of interest were compared between groups and correlation analyses were performed between electroencephalography (EEG) measures and clinical pain and functional outcomes in the knee OA group. Standard low-resolution electromagnetic brain tomography nonparametric maps revealed higher (P = .006) gamma band activity over the right insula (RIns) in the knee OA group. A significant (P < .0001) reduction in ISF band activity at the pregenual anterior cingulate cortex, whereas higher theta, alpha, beta, and gamma band activity at the dorsal anterior cingulate cortex, pregenual anterior cingulate cortex, the somatosensory cortex, and RIns in the knee OA group were identified. ISF activity of the dorsal anterior cingulate cortex was positively correlated with pain measures and psychological distress scores. Theta and alpha activity of RIns were negatively correlated with pain interference. In conclusion, aberrations in infraslow and faster frequency EEG oscillations at sensory discriminative, motivational-affective, and descending inhibitory cortical regions were demonstrated in people with chronic painful knee OA. Moreover, EEG oscillations were correlated with pain and functional outcome measures. PERSPECTIVE: This study confirms alterations in the rsEEG oscillations and its relationship with pain experience in people with knee OA. The study provides potential cortical targets and the EEG frequency bands for neuromodulatory interventions for managing chronic pain experience in knee OA.

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

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

Integrative approaches in spinal cord stimulation: Neuropathic pain management and motor recovery in spinal cord injury. A narrative review

Introduction

Spinal cord stimulation is a widespread treatment of chronic neuropathic pain from different conditions. Several novel and improving technologies have been recently developed to increase the effect of neuromodulation in patients refractory to pharmacological therapy.

Research question

To explore spinal cord stimulation's mechanisms of action, indications, and management.

Material and methods

The paper initially explores the mechanism of action of this procedure based on the generation of an electric field between electrodes placed on the posterior dural surface of the spinal cord probably interfering with the transmission of pain stimuli to the brain. Subsequently, the most consolidated criteria for selecting patients for surgery, which constitute a major issue of debate, were defined. Thereafter, the fundamental patterns of stimulation were summarized by exploring the advantages and side effects. Lastly, the most common side effects and the related management were discussed.

Results

Proper selection of the patient is of paramount importance to achieve the best results from this specific neuromodulation treatment. Regarding the different types of stimulation patterns, no definite evidence-based guidelines exist on the most appropriate approach in relation to the specific type of neuropathic pain. Both burst stimulation and high-frequency stimulation are innovative techniques that reduce the risk of paresthesias compared with conventional stimulation.

Discussion and conclusion

Novel protocols of stimulation (burst stimulation and high frequency stimulation) may improve the trade-off between therapeutic benefits and potential side effects. Likewise, decreasing the rates of hardware-related complications will be also useful to increase the application of neuromodulation in clinical settings.

Combined behavioral and EEG evidence for the 70 Hz frequency selection of short-term spinal cord stimulation in disorders of consciousness

OBJECTIVES

This study investigated the prognostic effect of electroencephalography (EEG) instant effects of single spinal cord stimulation (SCS) on clinical outcome in disorders of consciousness (DOC) and the time-dependent brain response during the recovery of consciousness prompted by SCS.

METHODS

Twenty three patients with DOC underwent short-term SCS (stSCS) implantation operation. Then, all patients received the postoperative EEG test including EEG record before (T1) and after (T2) single SCS session. Subsequently, 2 weeks stSCS treatment was performed and revised coma recovery scale (CRS-R) and EEG data were collected. Finally, they were classified into effective and ineffective groups at 3-month follow-up (T6).

RESULTS

The parietal-occipital (PO) connectivity and clustering coefficients (CC) in the beta band of the effective group at the 1 week after the treatment (T5) were found to be higher than preoperative assessment (T0). Correlation analysis showed that the change in beta CC at T1/T2 was correlated with the change in CRS-R at T0/T6. In addition, the change in PO connectivity and CC in the beta at T0/T5 were also correlated with the change in CRS-R at T0/T5.

CONCLUSION

SCS may facilitate the recovery of consciousness by enhancing local information interaction in posterior brain regions. And the recovery can be predicted by beta CC in the EEG test.

Exploratory evaluation of spinal cord stimulation with dynamic pulse patterns: a promising approach to improve stimulation sensation, coverage of pain areas, and expected pain relief

Background

The societal burden of chronic pain and the contribution-in-part to the opioid crisis, is a strong motivation to improve and expand non-addictive treatments, including spinal cord stimulation (SCS). For several decades standard SCS has consisted in delivery of tonic pulses with static parameter settings in frequency, pulse width, and amplitude. These static parameters have limited ability to personalize the quality of paresthesia, the dermatomal coverage, and thus may affect SCS efficacy. Further, static settings may contribute to the build-up of tolerance or loss of efficacy of the therapy over time in some patients.

Methods

We conducted an acute exploratory study to evaluate the effects of SCS using time-dynamic pulses as compared to time-static (conventional tonic) stimulation pulses, with the hypotheses that dynamic pulse SCS may enable beneficial tailoring of the sensation and the patient's expectation for better pain relief with SCS. During a single clinic visit, consented subjects undergoing a standard SCS trial had their implanted leads temporarily connected to an investigational external stimulator capable of delivering time-static and six categories of time-dynamic pulse sequences, each characterized by continuously varying a stimulation parameter. Study subjects provided several assessments while blinded to the stimulation pattern, including: drawing of paresthesia maps, descriptions of sensation, and ratings for comfort and helpfulness to pain relief.

Results

Even without optimization of the field location, a majority of subjects rated sensations from dynamic stimulation as better or equal to that of static stimulation for comfortableness and for helpfulness to pain relief. The initial data showed a gender and/or pain dermatomal location related preference to a stimulation pattern. In particular, female subjects and subjects with pain at higher dermatomes tended to rank the sensation from dynamic stimulation better. Dynamic stimulation produced greater pain coverage without optimization; in 70% (9/13) of subjects, maximal pain coverage was achieved with a dynamic stimulation pattern. There was also greater variety in the words used by patients to describe stimulation sensation in the free text and free form verbal descriptions associated with dynamic stimulation.

Conclusions

With the same electrode configuration and comparable parameter settings, acute SCS using dynamic pulses produced more positive ratings, expanded paresthesia coverage, and greater variation in sensation as compared to SCS using static pulses, suggesting that dynamic stimulation has the potential to improve capabilities of SCS for the treatment of chronic pain. Further study is warranted.

Trial Registration

This study was registered at ClinicalTrials.gov under ID NCT02988713, November 2016 (URL: https://clinicaltrials.gov/ct2/show/NCT02988713).

Burst Spinal Cord Stimulation as Compared With L2 Dorsal Root Ganglion Stimulation in Pain Relief for Nonoperated Discogenic Low Back Pain: Analysis of Two Prospective Studies

INTRODUCTION

Chronic discogenic low back pain (CD-LBP) is caused by degenerated disks marked by neural and vascular ingrowth. Spinal cord stimulation (SCS) has been shown to be effective for pain relief in patients who are not responsive to conventional treatments. Previously, the pain-relieving effect of two variations of SCS has been evaluated in CD-LBP: Burst SCS and L2 dorsal root ganglion stimulation (DRGS). The aim of this study is to compare the effectivity in pain relief and pain experience of Burst SCS with that of conventional L2 DRGS in patients with CD-LBP.

MATERIALS AND METHODS

Subjects were implanted with either Burst SCS (n = 14) or L2 DRGS with conventional stimulation (n = 15). Patients completed the numeric pain rating score (NRS) for back pain and Oswestry disability index (ODI) and EuroQoL 5D (EQ-5D) questionnaires at baseline, and at three, six, and 12 months after implantation. Data were compared between time points and between groups.

RESULTS

Both Burst SCS and L2 DRGS significantly decreased NRS, ODI, and EQ-5D scores as compared with baseline. L2 DRGS resulted in significantly lower NRS scores at 12 months and significantly increased EQ-5D scores at six and 12 months.

CONCLUSIONS

Both L2 DRGS and Burst SCS resulted in reduction of pain and disability, and increased quality of life in patients with CD-LBP. L2 DRGS provided significantly increased pain relief and improvement in quality of life when compared with Burst SCS.

CLINICAL TRIAL REGISTRATION

The clinical trial registration numbers for the study are NCT03958604 and NL54405.091.15.

Current Waveforms in Spinal Cord Stimulation and Their Impact on the Future of Neuromodulation: A Scoping Review

BACKGROUND

Neuromodulation is a standard and well-accepted treatment for chronic refractory neuropathic pain. There has been progressive innovation in the field over the last decade, particularly in areas of spinal cord stimulation (SCS) and dorsal root ganglion stimulation. Improved outcomes using proprietary waveforms have become customary in the field, leading to an unprecedented expansion of these products and a plethora of options for the management of pain. Although advances in waveform technology have improved our fundamental understanding of neuromodulation, a scoping review describing new energy platforms and their associated clinical effects and outcomes is needed. The authors submit that understanding electrophysiological neuromodulation may be important for clinical decision-making and programming selection for personalized patient care.

OBJECTIVE

This review aims to characterize ways differences in mechanism of action and clinical outcomes of current spinal neuromodulation products may affect contemporary clinical decision-making while outlining a possible path for the future SCS.

STUDY DESIGN

The study is a scoping review of the literature about newer generation SCS waveforms.

MATERIALS AND METHODS

A literature report was performed on PubMed and chapters to include articles on spine neuromodulation mechanism of action and efficacy.

RESULTS

A total of 8469 studies were identified, 75 of which were included for the scoping review after keywords defining recent waveform technology were added.

CONCLUSIONS

Clinical data suggest that neuromodulation remains a promising tool in the treatment of chronic pain. The evidence for SCS for treating chronic pain seems compelling; however, more long-term and comparative data are needed for a comparison of waveforms when it comes to the etiology of pain. In addition, an exploration into combination waveform therapy and waveform cycling may be paramount for future clinical studies and the development of new technologies.

Bilateral T12 Dorsal Root Ganglion Stimulation for the Treatment of Low Back Pain With 20-Hz and 4-Hz Stimulation, a Retrospective Study

OBJECTIVES

Chronic low back pain (CLBP) is one of the most common chronic pain conditions that cause both individual suffering and a burden to society. For these patients, several interventional treatment options such as surgery, blocks, radiofrequency, and spinal cord stimulation are available. Lately, dorsal root ganglion stimulation (DRG-S) also has been mentioned as an option by targeting bilateral T12 dorsal ganglia. In this study, we present the outcome of 11 patients with CLBP treated with bilateral T12 DRG-S.

MATERIALS AND METHODS

Thirteen patients with CLBP with and without leg pain were treated with bilateral T12 DRG-S. Three of the patients also received a third lumbar lead owing to leg pain. Eleven of the patients had >50% pain relief during the peri- or/and postoperative testing and received a fully implantable neurostimulator. Pain intensity, general health status, quality of life, pain catastrophizing, mental status, sleeping disorder, physical activity, and patient satisfaction were followed using numeric rating scale (NRS), Patient-Reported Outcomes Measurement Information System 29 version 2.1, Pain Catastrophizing Score, Generalized Anxiety Disorder 7-item scale, Patient Health Questionnaire Depression Module, Insomnia Severity Index, and Patient Satisfaction Questionnaire at baseline before implantation and at three months and six months. The results were analyzed on the basis of six domains: pain relief, sleeping disorder, social ability, mental status, physical activity, and satisfaction. To be identified as a responder, the patients should show a significant improvement in the pain relief domain together with at least two other domains. All responders also were given the opportunity to test 4-Hz DRG-S and compare it with traditional 20-Hz stimulation.

RESULTS

All 11 patients were identified as responders at six months. Five of the patients had >80% pain relief, with an average NRS score reduction of 71% for the whole group. Significant improvement could be observed in three domains for one patient, four domains for three patients, five domains for six patients, and six domains for one patient. Seven patients chose to try 4-Hz stimulation. All seven identified 4-Hz stimulation as at least as good as or better than 20-Hz stimulation and chose to continue with 4-Hz stimulation.

CONCLUSIONS

Bilateral T12 DRG-S seems to be an effective treatment for chronic low back pain, with significant beneficial effect not only on pain but also on quality of life, pain catastrophizing, mental status, sleeping disorder, and physical activity. 4-Hz DRG-S gave a result comparable with or better than 20-Hz stimulation.

Evaluation of Patient's Quality of Life before and after Implantation of Abbott's Proclaim™ XR Spinal Cord Stimulator with BurstDR™ Stimulation in Chronic Pain Syndrome

Background and Objectives: In case of the ineffectiveness of pharmacological and non-pharmacological treatments in managing chronic neuropathic pain, spinal cord stimulation (SCS) with BurstDR™ stimulation may reduce pain and increase the quality of life. The term "burst" refers to a series of stimulation impulses that are compressed into small packets and separated by intervals of latency. Materials and Methods: A group of 30 consecutive patients who received the BurstDR™ stimulator using the minimally invasive percutaneous method was selected. Patients selected for our study underwent numerous spinal surgeries before SCS implantation. In the study, analgesics and co-analgesics and their doses used by patients before and 6 months after SCS implantation were examined and compared. Using the visual analogue scale (VAS), pain was compared before and after the procedure. Patients` quality of life was assessed using the Oswestry Disability Index (ODI). Results: We observed a significant reduction in opioid daily doses by an average of 32.4% (±36.1%) and a reduction in paracetamol daily doses by an average of 40% (±33.4%). There was a reduction in pregabalin doses as well. Ketoprofen daily dose reduction was 85.4 mg. The mean VAS difference before and after procedure was 3.9 (±2.3), and the mean difference in ODI was 12.9 (±9), which benefits operative treatment. The VAS and ODI results were statistically significant as well. Conclusions: According to our research, BurstDR™ stimulation improves the quality of life by reducing doses of analgesics and the level of pain.

A Bibliometric Analysis of Top-Cited Journal Articles Related to Neuromodulation for Chronic Pain

OBJECTIVES

Since its foundation in the 1960s, neuromodulation has become an increasingly used treatment option for chronic pain. This bibliometric analysis examines the most cited research in this field with the aim of uncovering existing trends and future directions.

MATERIALS AND METHODS

Clarivate's Web of Science data base was searched for the top 25 most cited studies focusing on neuromodulation for chronic pain. Various bibliometric parameters were then extracted and analyzed. Randomized controlled trials (RCTs) were compared with non-RCTs.

RESULTS

The top 25 articles had a mean of 347 citations and 22.2 citations per year, with more recent articles having a higher citation rate. Most were published in the last two decades and predominantly originated from the United States. There were 13 RCTs, which were significantly more recent (p = 0.004) and more cited per year (p = 0.001) than the 12 non-RCTs. Sources included 15 journals with a mean impact factor of 13.896. The most studied modality was spinal cord stimulation with 20 articles (76.9%), followed by intrathecal drug delivery (15.4%), dorsal root ganglion stimulation (3.8%), and peripheral nerve stimulation (3.8%).

CONCLUSIONS

Analysis of the most cited articles on neuromodulation reveals a focal shift from historical reports to innovative RCTs that have increasingly guided pain practice in the recent years. As novel techniques and technologies continue to develop, high-quality evidence coupled with broadening indications will likely direct further expansion of this field.

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

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

Blockage of pain by electrical spinal cord stimulation

BACKGROUND

Electrical spinal cord stimulation (SCS) is an alternative to conventional medication for chronic pain relief. Several hypotheses exist concerning the neurophysiological, vascular, and neurochemical mechanism behind SCS.

METHODS

The excitation and blockade effects of the three common SCS waveforms (tonic, burst, and high-frequency stimulation) on the nerve fibers bypassing the region of the electrodes are analyzed in a computational study. The simulations are based on the model of Hodgkin and Huxley which is fitted to spike durations of 1 ms.

RESULTS

SCS is a FDA approved technique for pain relief, but the mechanisms of action are still under investigation. The first element in the chain of mechanisms is the generation and the block of spikes in nerve fibers close to the stimulating electrode. For these "primary fibers" computer simulations showed that conventional SCS generates sharply synchronized spikes whereas the spread of the spiking times by burst stimulation is expected to cause the suppression of paresthesia. This rather uniform spread of spiking times (in comparison to tonic stimulation) is a consequence of more pulses (5 vs. 1), longer pulses, and increasing intensities within each train of 5 pulses.

CONCLUSIONS

High-frequency stimulation can block the conduction of spikes but the distance of the fiber to the lead is a critical factor.

Epidural Laterality and Pain Relief With Burst Spinal Cord Stimulation

INTRODUCTION

Burst spinal cord stimulation (SCS) can achieve excellent clinical reduction of pain, alongside improvements in function, quality of life, and related outcomes. Good outcomes likely depend on good lead placement, thereby enabling recruitment of the relevant neural targets. Several competing approaches exist for lead implantation, such as the use of single vs bilateral leads and leads lateralized vs placed at midline. The objective of this study was to examine the relationship between paresthesia locations and pain relief with burst SCS in a prospective double-blind crossover design.

MATERIALS AND METHODS

All participants had bilateral back and leg pain, with more intense pain experienced on one side of the body. A trial SCS system was placed, during which brief intraoperative mapping with conventional stimulation was used to characterize paresthesia locations. Two programs for subperception burst SCS treatment were then applied for two days each, in random order: bilateral paresthesia coverage vs unilateral paresthesia coverage contralateral to the side of the body with more intense pain. Pain ratings (visual analog scale [VAS]) and pain reductions (scaling pain relief [SPR]) were reported for each.

RESULTS

Of the 30 participants who completed the study, 24 (80%) had good pain relief with at least one program. A baseline VAS score of 8.75 was reduced to 5.98 with contralateral stimulation and to 2.88 with bilateral stimulation; with SPR, this equated to 31.25% and 67.50% improvement, respectively. The incremental benefit of bilateral stimulation over contralateral stimulation was statistically significant (p < 0.001). Of the 24 participants, 87.5% preferred bilateral stimulation, whereas 12.5% preferred unilateral stimulation. The six participants who failed the trial had no preference.

DISCUSSION

When burst stimulation is delivered to spinal targets that can generate paresthesias contralateral to the side of worst pain, suboptimal therapy is achieved. Thus, attention to laterality and pain coverage is critical for successful therapy, and it may be important to carefully consider lead implantation techniques.

Treatment of Refractory Low Back Pain Using Passive Recharge Burst in Patients Without Options for Corrective Surgery: Findings and Results From the DISTINCT Study, a Prospective Randomized Multicenter Controlled Trial

OBJECTIVE

Spinal cord stimulation (SCS) is effective for relieving chronic intractable pain conditions. The Dorsal spInal cord STImulatioN vs mediCal management for the Treatment of low back pain study evaluates the effectiveness of SCS compared with conventional medical management (CMM) in the treatment of chronic low back pain in patients who had not undergone and were not candidates for lumbar spine surgery.

METHODS AND MATERIALS

Patients were randomized to passive recharge burst therapy (n = 162) or CMM (n = 107). They reported severe pain and disability for more than a decade and had failed a multitude of therapies. Common diagnoses included degenerative disc disease, spondylosis, stenosis, and scoliosis-yet not to a degree amenable to surgery. The six-month primary end point compared responder rates, defined by a 50% reduction in pain. Hierarchical analyses of seven secondary end points were performed in the following order: composite responder rate (numerical rating scale [NRS] or Oswestry Disability Index [ODI]), NRS, ODI, Pain Catastrophizing Scale responder rate, Patient Global Impression of Change (PGIC) responder rate, and Patient-Reported Outcome Measure Information System-29 in pain interference and physical function.

RESULTS

Intention-to-treat analysis showed a significant difference in pain responders on NRS between SCS (72.6%) and CMM (7.1%) arms (p < 0.0001). Of note, 85.2% of those who received six months of therapy responded on NRS compared with 6.2% of those with CMM (p < 0.0001). All secondary end points indicated the superiority of burst therapy over CMM. A composite measure on function or pain relief showed 91% of subjects with SCS improved, compared with 16% of subjects with CMM. A substantial improvement of 30 points was observed on ODI compared with a

CONCLUSIONS

This study found substantial improvement at six months in back pain, back pain-related disability, pain-related emotional suffering, PGIC, pain interference, and physical function in a population with severe, debilitating back pain for more than a decade. These improvements were reported in conjunction with reduced opioid use, injection, and ablation therapy.

CLINICAL TRIAL REGISTRATION

The Clinicaltrials.gov registration number for the study is NCT04479787.

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Key Words

• composite outcomes
• persistent spinal pain syndrome
• refractory chronic low back pain
• spinal cord stimulation

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MESH Headings

• Humans
• Low Back Pain/therapy
• Low Back Pain/psychology
• Treatment Outcome
• Prospective Studies
• Back Pain
• Spinal Cord Stimulation/methods
• Chronic Pain/diagnosis
• Chronic Pain/therapy

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Grants

• K08 CA228039 NCI NIH HHS

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Affiliation(s)

Timothy Deer The Spine and Nerve Center of the Virginias, Charleston, WV, USA
Christopher Gilligan Brigham & Women's Hospital, Boston, MA, USA
Steven Falowski Center for Interventional Pain & Spine, Lancaster, PA, USA
Mehul Desai International Spine, Pain & Performance Center, Washington, DC, USA
Julie Pilitsis Florida Atlantic University, FL, USA
Jessica Jameson Axis Spine Center, ID, USA
Susan Moeschler Mayo Clinic, Rochester, NY, USA
Robert Heros Spinal Diagnostics, OR, USA
Edward Tavel Clinical Trials of South Carolina, Charleston, SC, USA
Anne Christopher Saint Louis Pain Consultants, Chesterfield, MO, USA
Denis Patterson Nevada Advanced Pain Specialists, Reno, NV, USA
Sayed Wahezi Montefiore Medical Center-Waters Place, New York, NY, USA
Jacqueline Weisbein Napa Valley Orthopedic Medical Group, Napa, CA, USA
Ajay Antony The Orthopaedic Institute, FL, USA
Robert Funk Indiana Spine Group, IN, USA
Mohab Ibrahim Banner University Medical Center Tucson Campus, Tucson, AZ, USA
Chi Lim Carolina Orthopaedic & Neurosurgical Associates, SC, USA
Derron Wilson Goodman Campbell Brain & Spine, IN, USA
Michael Fishell Advanced Pain Care, NV, USA
Keith Scarfo Rhode Island Hospital, Providence, RI, USA
David Dickerson Northshore University HealthSystem, Chicago, IL, USA
Edward Braun Kansas University Medical Center, KS, USA
Patrick Buchanan Spanish Hills Interventional Pain Specialists, Camarillo, CA, USA
Robert M Levy Anesthesia Pain Care Consultants-Tamarac
Nathan Miller Coastal Pain & Spinal Diagnostics Medical Group, Carlsbad, CA, USA
Jonathan Duncan Burkhart Research Institute for Orthopaedics, San Antonio, TX, USA
Jijun Xu The Cleveland Clinic Foundation, OH, USA
Kenneth Candido Chicago Anesthesia Associates, SC, Chicago, IL, USA
Scott Kreiner Barrow Brain & Spine-Ahwatukee, Phoenix, AZ, USA
Marie E Fahey Abbott Labs, Austin, TX, USA
James Yue Connecticut Orthopaedics, CT, USA

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Fully Implantable Neurostimulation System for Long-Term Behavioral Animal Study

Spinal cord stimulation (SCS) is an emerging therapeutic option for patients with neuropathic pain due to spinal cord injury (SCI). Numerous studies on pain relief effects with SCS have been conducted and demonstrated promising results while the mechanisms of analgesic effect during SCS remain unclear. However, an experimental system that enables large-scale long-term animal studies is still an unmet need for those mechanistic studies. This study proposed a fully wireless neurostimulation system that can efficiently support a long-term animal study for neuropathic pain relief. The developed system consists of an implantable stimulator, an animal cage with an external charging coil, and a wireless communication interface. The proposed device has the feature of remotely controlling stimulation parameters via radio-frequency (RF) communication and wirelessly charging via magnetic induction in freely moving rats. Users can program stimulation parameters such as pulse width, intensity, and duration through an interface on a computer. The stimulator was packaged with biocompatible epoxy to ensure long-term durability under in vivo conditions. Animal experiments using SCI rats were conducted to demonstrate the functionality of the device, including long-term usability and therapeutic effects. The developed system can be tailored to individual user needs with commercially available components, thus providing a cost-effective solution for large-scale long-term animal studies on neuropathic pain relief.

Pain Education and Knowledge (PEAK) Consensus Guidelines for Neuromodulation: A Proposal for Standardization in Fellowship and Training Programs

The need to be competent in neuromodulation is and should be a prerequisite prior to completing a fellowship in interventional pain medicine. Unfortunately, many programs lack acceptable candidates for these advanced therapies, and fellows may not receive adequate exposure to neuromodulation procedures. The American Society of Pain and Neuroscience (ASPN) desires to create a consensus of experts to set a minimum standard of competence for neurostimulation procedures, including spinal cord stimulation (SCS), dorsal root ganglion stimulation (DRG-S), and peripheral nerve stimulation (PNS). The executive board of ASPN accepted nominations for colleagues with excellence in the subject matter of neuromodulation and physician education. This diverse group used peer-reviewed literature and, based on grading of evidence and expert opinion, developed critical consensus guides for training that all accredited fellowship programs should adopt. For each consensus point, transparency and recusal were used to eliminate bias, and an author was nominated for evidence grading oversight and bias control. Pain Education and Knowledge (PEAK) Consensus Guidelines for Neuromodulation sets a standard for neuromodulation training in pain fellowship training programs. The consensus panel has determined several recommendations to improve care in the United States for patients undergoing neuromodulation. As neuromodulation training in the United States has evolved dramatically, these therapies have become ubiquitous in pain medicine. Unfortunately, fellowship programs and the Accreditation Council for Graduate Medical Education (ACGME) pain program requirements have not progressed training to match the demands of modern advancements. PEAK sets a new standard for fellowship training and presents thirteen practice areas vital for physician competence in neuromodulation.

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

Background and objectives

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

Literature review

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

Case report

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

Conclusion

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

BurstDR spinal cord stimulation rebalances pain input and pain suppression in the brain in chronic neuropathic pain

OBJECTIVE

Chronic pain is processed by at least three well-known pathways, two pain provoking pathways including a medial 'suffering' and lateral 'painfulness' pathway. A third descending pain pathway modulates pain but is predominantly inhibitory. Chronic pain can be seen as an imbalance between the two pain-provoking and the pain inhibitory pathways. If this assumption is correct, then the imbalance between pain input and pain suppression should reverse and normalize in response to successful, i.e., pain reducing burstDR spinal cord stimulation, one of the current treatment options for neuropathic pain.

MATERIALS AND METHODS

Fifteen patients, who received spinal cord stimulation for failed back surgery were included in this study, using source localized electrical brain activity and connectivity recording via EEG to identify the purported imbalance.

RESULTS

BurstDR spinal cord stimulation induces a significant change in EEG activity in both the left and right somatosensory cortex (SSC) for both θ and γ oscillations. In the dorsal anterior cingulate cortex (dACC), we observed a significant drop in both α and β oscillations. This reduction is accompanied by a change in pain intensity and suffering. BurstDR spinal cord stimulation is also associated with a reduction in θ at the pregenual anterior cingulate cortex (pgACC). Analyzing effective connectivity indicates that for the θ band, more information is sent from the pgACC to the left and right SSC. For α, increased information is sent from the pgACC to the dACC and both the left and right SSC. This is associated with a reduced θ-γ coupling in the SSC and reduced α-β coupling in dACC.

CONCLUSION

This study suggests that chronic pain is indeed an imbalance between the ascending and descending pathways in the brain and that burst spinal cord stimulation can normalize this imbalance in the brain.

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

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

Evidence-based consensus guidelines on patient selection and trial stimulation for spinal cord stimulation therapy for chronic non-cancer pain

Spinal cord stimulation (SCS) has demonstrated effectiveness for neuropathic pain. Unfortunately, some patients report inadequate long-term pain relief. Patient selection is emphasized for this therapy; however, the prognostic capabilities and deployment strategies of existing selection techniques, including an SCS trial, have been questioned. After approval by the Board of Directors of the American Society of Regional Anesthesia and Pain Medicine, a steering committee was formed to develop evidence-based guidelines for patient selection and the role of an SCS trial. Representatives of professional organizations with clinical expertize were invited to participate as committee members. A comprehensive literature review was carried out by the steering committee, and the results organized into narrative reports, which were circulated to all the committee members. Individual statements and recommendations within each of seven sections were formulated by the steering committee and circulated to members for voting. We used a modified Delphi method wherein drafts were circulated to each member in a blinded fashion for voting. Comments were incorporated in the subsequent revisions, which were recirculated for voting to achieve consensus. Seven sections with a total of 39 recommendations were approved with 100% consensus from all the members. Sections included definitions and terminology of SCS trial; benefits of SCS trial; screening for psychosocial characteristics; patient perceptions on SCS therapy and the use of trial; other patient predictors of SCS therapy; conduct of SCS trials; and evaluation of SCS trials including minimum criteria for success. Recommendations included that SCS trial should be performed before a definitive SCS implant except in anginal pain (grade B). All patients must be screened with an objective validated instrument for psychosocial factors, and this must include depression (grade B). Despite some limitations, a trial helps patient selection and provides patients with an opportunity to experience the therapy. These recommendations are expected to guide practicing physicians and other stakeholders and should not be mistaken as practice standards. Physicians should continue to make their best judgment based on individual patient considerations and preferences.

Research hotspots and trends on spinal cord stimulation for pain treatment: a two-decade bibliometric analysis

Background

Chronic pain poses a significant social burden. Spinal cord stimulation (SCS) is considered to be the most promising treatment for refractory pain. The aim of this study was to summarize the current research hotspots on SCS for pain treatment during the past two decades and to predict the future research trends by bibliometric analysis.

Methods

The literature over the last two decades (2002-2022) which was related to SCS in pain treatment was obtained from the Web of Science Core Collection. Bibliometric analyses were conducted based on the following aspects: (1) Annual publication and citation trends; (2) Annual publication changes of different publication types; (3) Publications and citations/co-citations of different country/institution/journal/author; (4) Citations/co-citation and citation burst analysis of different literature; and (5) Co-occurrence, cluster, thematic map, trend topics, and citation burst analysis of different keywords. (6) Comparison between the United States and Europe. All analyses were performed on CiteSpace, VOSviewer, and R bibliometrix package.

Results

A total of 1,392 articles were included in this study, with an increasing number of publications and citations year by year. The most highly published type of literature was clinical trial. United States was the country with the most publications and citations; Johns Hopkins University was the institution with the most publications; NEUROMODULATION published the most papers; the most published author was Linderoth B; and the most cited paper was published in the PAIN by Kumar K in 2007. The most frequently occurring keywords were "spinal cord stimulation," "neuropathic pain," and "chronic pain," etc.

Conclusion

The positive effect of SCS on pain treatment has continued to arouse the enthusiasm of researchers in this field. Future research should focus on the development of new technologies, innovative applications, and clinical trials for SCS. This study might facilitate researchers to comprehensively understand the overall perspective, research hotspots, and future development trends in this field, as well as seek collaboration with other researchers.

Supraorbital Nerve Stimulation for Facial Pain

PURPOSE OF REVIEW

Chronic facial pain is considered one of the conditions that affect quality of daily life of patients significantly and makes them seek medical help. Intractable facial pain with failed trials of medical treatment and other pain management therapies presents a challenge for neurologists, pain specialists, and neurosurgeons. We describe the possibility of proposing peripheral nerve stimulation of the supraorbital nerves to treat patients with medically intractable facial pain. Stimulation of the supraorbital nerves is performed using percutaneously inserted electrodes that are positioned in the epi-fascial plane, traversing the course of the supraorbital nerves. The procedure has two phases starting with a trial by temporary electrodes that are inserted under fluoroscopic guidance and are anchored to the skin. This trial usually lasts for a few days to 2 weeks. If successful, we proceed to the insertion of a permanent electrode that is tunneled under the skin behind the ear toward the infraclavicular region in which we make a pocket for the implantable pulse generator.

RECENT FINDINGS

This procedure has been used in multiple patients with promising results which was published in literature. Literature shows that it provides relief of medically intractable pain, without the need for destructive procedures or more central modulation approaches with a preferable safety profile compared to other invasive procedures. Supraorbital nerve stimulation is now considered a valid modality of treatment for patients with medically intractable facial pain and can be offered as a reliable alternative for the patients while discussing the proper plan of management.

The Peripheral Nerve Surgeon's Role in the Management of Neuropathic Pain

Neuropathic pain (NP) underlies significant morbidity and disability worldwide. Although pharmacologic and functional therapies attempt to address this issue, they remain incompletely effective for many patients. Peripheral nerve surgeons have a range of techniques for intervening on NP. The aim of this review is to enable practitioners to identify patients with NP who might benefit from surgical intervention. The workup for NP includes patient history and specific physical examination maneuvers, as well as imaging and diagnostic nerve blocks. Once diagnosed, there is a range of options surgeons can utilize based on specific causes of NP. These techniques include nerve decompression, nerve reconstruction, nerve ablative techniques, and implantable nerve-modulating devices. In addition, there is an emerging role for preoperative involvement of peripheral nerve surgeons for cases known to carry a high risk of inducing postoperative NP. Lastly, we describe the ongoing work that will enable surgeons to expand their armamentarium to better serve patients with NP.

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.

Narrative review of current neuromodulation modalities for spinal cord injury

Neuromodulation is a developing field of medicine that includes a vast array of minimally invasive and non-invasive therapies including transcranial magnetic stimulation (TMS), transcranial direct current stimulation (tDCS), vagus nerve stimulation (VNS), peripheral nerve stimulation, and spinal cord stimulation (SCS). Although the current literature surrounding the use of neuromodulation in managing chronic pain is abundant, there is an insufficient amount of evidence specifically regarding neuromodulation in patients with spinal cord injury (SCI). Given the pain and functional deficits that these patients face, that are not amenable to other forms conservative therapy, the purpose of this narrative review is to examine and assess the use of various neuromodulation modalities to manage pain and restore function in the SCI population. Currently, high-frequency spinal cord stimulation (HF-SCS) and burst spinal cord stimulation (B-SCS) have been shown to have the most promising effect in improving pain intensity and frequency. Additionally, dorsal root ganglion stimulation (DRG-S) and TMS have been shown to effectively increase motor responses and improve limb strength. Although these modalities carry the potential to enhance overall functionality and improve a patient's degree of disability, there is a lack of long-term, randomized-controlled trials in the current space. Additional research is warranted to further support the clinical use of these emerging modalities to provide improved pain management, increased level of function, and ultimately an overall better quality of life in the SCI population.

Spinal cord stimulation for low back pain

BACKGROUND

Spinal cord stimulation (SCS) is a surgical intervention used to treat persistent low back pain. SCS is thought to modulate pain by sending electrical signals via implanted electrodes into the spinal cord. The long term benefits and harms of SCS for people with low back pain are uncertain.

OBJECTIVES

To assess the effects, including benefits and harms, of SCS for people with low back pain.

SEARCH METHODS

On 10 June 2022, we searched CENTRAL, MEDLINE, Embase, and one other database for published trials. We also searched three clinical trials registers for ongoing trials.

SELECTION CRITERIA

We included all randomised controlled trials and cross-over trials comparing SCS with placebo or no treatment for low back pain. The primary comparison was SCS versus placebo, at the longest time point measured in the trials. Major outcomes were mean low back pain intensity, function, health-related quality of life, global assessment of efficacy, withdrawals due to adverse events, adverse events, and serious adverse events. Our primary time point was long-term follow-up (≥ 12 months).

DATA COLLECTION AND ANALYSIS

We used standard methodological procedures expected by Cochrane.

MAIN RESULTS

We included 13 studies with 699 participants: 55% of participants were female; mean age ranged from 47 to 59 years; and all participants had chronic low back pain with mean duration of symptoms ranging from five to 12 years. Ten cross-over trials compared SCS with placebo. Three parallel-group trials assessed the addition of SCS to medical management. Most studies were at risk of performance and detection bias from inadequate blinding and selective reporting bias. The placebo-controlled trials had other important biases, including lack of accounting for period and carryover effects. Two of the three parallel trials assessing SCS as an addition to medical management were at risk of attrition bias, and all three had substantial cross-over to the SCS group for time points beyond six months. In the parallel-group trials, we considered the lack of placebo control to be an important source of bias. None of our included studies evaluated the impact of SCS on mean low back pain intensity in the long term (≥ 12 months). The studies most often assessed outcomes in the immediate term (less than one month). At six months, the only available evidence was from a single cross-over trial (50 participants). There was moderate-certainty evidence that SCS probably does not improve back or leg pain, function, or quality of life compared with placebo. Pain was 61 points (on a 0- to 100-point scale, 0 = no pain) at six months with placebo, and 4 points better (8.2 points better to 0.2 points worse) with SCS. Function was 35.4 points (on a 0- to 100-point scale, 0 = no disability or best function) at six months with placebo, and 1.3 points better (3.9 points better to 1.3 points worse) with SCS. Health-related quality of life was 0.44 points out of 1 (0 to 1 index, 0 = worst quality of life) at six months with placebo, and 0.04 points better (0.16 points better to 0.08 points worse) with SCS. In that same study, nine participants (18%) experienced adverse events and four (8%) required revision surgery. Serious adverse events with SCS included infections, neurological damage, and lead migration requiring repeated surgery. We could not provide effect estimates of the relative risks as events were not reported for the placebo period. In parallel trials assessing SCS as an addition to medical management, it is uncertain whether, in the medium or long term, SCS can reduce low back pain, leg pain, or health-related quality of life, or if it increases the number of people reporting a 50% improvement or better, because the certainty of the evidence was very low. Low-certainty evidence suggests that adding SCS to medical management may slightly improve function and slightly reduce opioid use. In the medium term, mean function (0- to 100-point scale; lower is better) was 16.2 points better with the addition of SCS to medical management compared with medical management alone (95% confidence interval (CI) 19.4 points better to 13.0 points better; I2 = 95%; 3 studies, 430 participants; low-certainty evidence). The number of participants reporting opioid medicine use was 15% lower with the addition of SCS to medical management (95% CI 27% lower to 0% lower; I2 = 0%; 2 studies, 290 participants; low-certainty evidence). Adverse events with SCS were poorly reported but included infection and lead migration. One study found that, at 24 months, 13 of 42 people (31%) receiving SCS required revision surgery. It is uncertain to what extent the addition of SCS to medical management increases the risk of withdrawals due to adverse events, adverse events, or serious adverse events, because the certainty of the evidence was very low.

AUTHORS' CONCLUSIONS

Data in this review do not support the use of SCS to manage low back pain outside a clinical trial. Current evidence suggests SCS probably does not have sustained clinical benefits that would outweigh the costs and risks of this surgical intervention.

Neuropathic pain questionnaires for back pain, what do we know?

INTRODUCTION

Low back pain is a global public health concern, with an estimated lifetime prevalence of 84%. Axial low back pain refers to pain confined to an area in the low back and is different to radicular pain which radiates to extremities. Axial low back pain has traditionally been considered as nociceptive. However, research suggests it may have neuropathic components. Neuropathic axial low back pain is an unresolved, hotly contested topic due to controversies surrounding its aetiology, diagnosis, clinical course, prognosis and treatment options.

PURPOSE

The reference standard for diagnosing neuropathic pain is by medical history and clinical assessment (i.e., sensory testing), with optional neuropathic screening tools and selective, further diagnostic tests when clinically needed. Neuropathic screening tools are not always specific for neuropathic radiating low back pain, let alone neuropathic axial low back pain. Additionally, not all have been validated for the English language (e.g., PainDETECT). Research also suggests the percentage of patients identified as having neuropathic radiating low back pain may be dependent on the combination of reference standards used.

IMPLICATIONS

There is a need for research that works towards improving understanding of neuropathic axial low back pain and developing a standardised, validated and reliable system for assessing and identifying this condition. This body of research will promote earlier stratification and more rapid referral for appropriate treatment, and improve awareness, assessment and visibility of this condition amongst healthcare practitioners and in healthcare settings. This will lead to transformations in Pathways and health guidelines, ultimately improving patient outcomes.

Heterogeneous Cortical Effects of Spinal Cord Stimulation

OBJECTIVES

The understanding of the cortical effects of spinal cord stimulation (SCS) remains limited. Multiple studies have investigated the effects of SCS in resting-state electroencephalography. However, owing to the large variation in reported outcomes, we aimed to describe the differential cortical responses between two types of SCS and between responders and nonresponders using magnetoencephalography (MEG).

MATERIALS AND METHODS

We conducted 5-minute resting-state MEG recordings in 25 patients with chronic pain with active SCS in three sessions, each after a one-week exposure to tonic, burst, or sham SCS. We extracted six spectral features from the measured neurophysiological signals: the alpha peak frequency; alpha power ratio (power 7-9 Hz/power 9-11 Hz); and average power in the theta (4-7.5 Hz), alpha (8-12.5 Hz), beta (13-30 Hz), and low-gamma (30.5-60 Hz) frequency bands. We compared these features (using nonparametric permutation t-tests) for MEG sensor and cortical map effects across stimulation paradigms, between participants who reported low (< 5, responders) vs high (≥ 5, nonresponders) pain scores, and in three representative participants.

RESULTS

We found statistically significant (p < 0.05, false discovery rate corrected) increased MEG sensor signal power below 3 Hz in response to burst SCS compared with tonic and sham SCS. We did not find statistically significant differences (all p > 0.05) between the power spectra of responders and nonresponders. Our data did not show statistically significant differences in the spectral features of interest among the three stimulation paradigms or between responders and nonresponders. These results were confirmed by the MEG cortical maps. However, we did identify certain trends in the MEG source maps for all comparisons and several features, with substantial variation across participants.

CONCLUSIONS

The considerable variation in cortical responses to the various SCS treatment options necessitates studies with sample sizes larger than commonly reported in the field and more personalized treatment plans. Studies with a finer stratification between responders and nonresponders are required to advance the knowledge on SCS treatment effects.

The role of virtual reality as adjunctive therapy to spinal cord stimulation in chronic pain: A feasible concept?

Spinal cord stimulation and virtual reality therapy are established and promising techniques, respectively, for managing chronic pain, each with its unique advantages and challenges. While each therapy has been the subject of significant research interest, the prospect of combining the two modalities to offer a synergistic effect in chronic pain therapy is still in its infancy. In this narrative review, we assess the state of the field combining virtual reality as an adjunctive therapy to spinal cord stimulation in chronic pain. We also review the broader field of virtual reality therapy for acute and chronic pain, considering evidence related to feasibility in the Canadian healthcare system from cost and patient satisfaction perspectives. While early results show promise, there are unexplored aspects of spinal cord stimulation combined with virtual reality therapy, particularly long-term effects on analgesia, anxiolysis, and implications on the effectiveness and longevity of spinal cord stimulation. The infrastructure for billing virtual reality as a consult service or therapy must also catch up if it is eventually used to supplement spinal cord stimulation for chronic pain.

A Review of Effects of Spinal Cord Stimulation on Spectral Features in Resting-State Electroencephalography

BACKGROUND

Spinal cord stimulation (SCS) is an effective therapy for patients with refractory chronic pain syndromes. Although studies have shown that SCS has both spinal and supraspinal effects, the current understanding of cortical effects is still limited. Neuroimaging techniques, such as magnetoencephalography (MEG) and electroencephalography (EEG), combined here as M/EEG, can reveal modulations in ongoing resting-state cortical activity. We aim to provide an overview of available literature on resting-state M/EEG in patients with chronic pain who have been treated with SCS.

MATERIALS AND METHODS

We searched multiple online data bases for studies on SCS, chronic pain, and resting-state M/EEG. Primary outcome measures were changes in spectral features, combined with brain regions in which these changes occurred.

RESULTS

We included eight studies reporting various SCS paradigms (tonic, burst, high-dose, and high-frequency stimulation) and revealing heterogeneity in outcome parameters. We summarized changes in cortical activity in various frequency bands: theta (4-7 Hz), alpha (7-12 Hz), beta (13-30 Hz), and gamma (30-44 Hz). In multiple studies, the somatosensory cortex showed modulation of cortical activity under tonic, burst, and high-frequency stimulation. Changes in connectivity were found in the dorsal anterior cingulate cortex, dorsolateral prefrontal cortex, and parahippocampus.

CONCLUSIONS

The large heterogeneity observed in outcome measures is probably caused by the large variety in study designs, stimulation paradigms, and spectral features studied. Paresthesia-free paradigms have been compared with tonic stimulation in multiple studies. These studies suggest modulation of medial, lateral, and descending pathways for paresthesia-free stimulation, whereas tonic stimulation predominantly modulates lateral and descending pathways. Moreover, multiple studies have reported an increased alpha peak frequency, increased alpha power, and/or decreased theta power when SCS was compared with baseline, indicating modulation of thalamocortical pathways. Further studies with well-defined groups of responders and nonresponders to SCS are recommended to independently study the cortical effects of pain relief and SCS.

Effect of Spinal Cord Burst Stimulation vs Placebo Stimulation on Disability in Patients With Chronic Radicular Pain After Lumbar Spine Surgery: A Randomized Clinical Trial

IMPORTANCE

The use of spinal cord stimulation for chronic pain after lumbar spine surgery is increasing, yet rigorous evidence of its efficacy is lacking.

OBJECTIVE

To investigate the efficacy of spinal cord burst stimulation, which involves the placement of an implantable pulse generator connected to electrodes with leads that travel into the epidural space posterior to the spinal cord dorsal columns, in patients with chronic radiculopathy after surgery for degenerative lumbar spine disorders.

DESIGN, SETTING, AND PARTICIPANTS

This placebo-controlled, crossover, randomized clinical trial in 50 patients was conducted at St Olavs University Hospital in Norway, with study enrollment from September 5, 2018, through April 28, 2021. The date of final follow-up was May 20, 2022.

INTERVENTIONS

Patients underwent two 3-month periods with spinal cord burst stimulation and two 3-month periods with placebo stimulation in a randomized order. Burst stimulation consisted of closely spaced, high-frequency electrical stimuli delivered to the spinal cord. The stimulus consisted of a 40-Hz burst mode of constant-current stimuli with 4 spikes per burst and an amplitude corresponding to 50% to 70% of the paresthesia perception threshold.

MAIN OUTCOMES AND MEASURES

The primary outcome was difference in change from baseline in the self-reported Oswestry Disability Index (ODI; range, 0 points [no disability] to 100 points [maximum disability]; the minimal clinically important difference was 10 points) score between periods with burst stimulation and placebo stimulation. The secondary outcomes were leg and back pain, quality of life, physical activity levels, and adverse events.

RESULTS

Among 50 patients who were randomized (mean age, 52.2 [SD, 9.9] years; 27 [54%] were women), 47 (94%) had at least 1 follow-up ODI score and 42 (84%) completed all stimulation randomization periods and ODI measurements. The mean ODI score at baseline was 44.7 points and the mean changes in ODI score were -10.6 points for the burst stimulation periods and -9.3 points for the placebo stimulation periods, resulting in a mean between-group difference of -1.3 points (95% CI, -3.9 to 1.3 points; P = .32). None of the prespecified secondary outcomes showed a significant difference. Nine patients (18%) experienced adverse events, including 4 (8%) who required surgical revision of the implanted system.

CONCLUSIONS AND RELEVANCE

Among patients with chronic radicular pain after lumbar spine surgery, spinal cord burst stimulation, compared with placebo stimulation, after placement of a spinal cord stimulator resulted in no significant difference in the change from baseline in self-reported back pain-related disability.

TRIAL REGISTRATION

ClinicalTrials.gov Identifier: NCT03546738.

Spinal Cord Stimulation in Chronic Low Back Pain Syndrome: Mechanisms of Modulation, Technical Features and Clinical Application

Chronic low-back pain (CLBP) is a common disease with several negative consequences on the quality of life, work and activity ability and increased costs to the health-care system. When pharmacological, psychological, physical and occupational therapies or surgery fail to reduce CLBP, patients may be a candidate for Spinal Cord Stimulation (SCS). SCS consists of the transcutaneous or surgical implantation of different types of electrodes in the epidural space; electrodes are then connected to an Implanted Pulse Generator (IPG) that generates stimulating currents. Through spinal and supraspinal mechanisms based on the “gate control theory for pain transmission”, SCS reduces symptoms of CLBP in the almost totality of well-selected patients and its effect lasts up to eight years in around 75% of patients. However, the evidence in favor of SCS still remains weak, mainly due to poor trial methodology and design. This narrative review is mainly addressed to those professionals that may encounter patients with CLBP failing conventional treatments. For this reason, we report the mechanisms of pain relief during SCS, the technical features and some clinical considerations about the application of SCS in patients with CLBP.

Study protocol: Effects of active versus passive recharge burst spinal cord stimulation on pain experience in persistent spinal pain syndrome type 2: a multicentre randomized trial (BURST-RAP study)

Background

Spinal cord stimulation (SCS) has shown to be an effective treatment for patients with persistent spinal pain syndrome type 2 (PSPS Type 2). The method used to deliver electrical charge in SCS is important. One such method is burst stimulation. Within burst stimulation, a recharge pattern is used to prevent buildup of charge in stimulated tissues. Two variations of burst waveforms are currently in use: one that employs active recharge and one that uses passive recharge. It has been suggested that differences exist between active and passive recharge paradigms related to both efficacy of pain relief and their underlying mechanism of action. Active recharge has been shown to activate both the medial spinal pathway, engaging cortical sensorimotor areas involved in location and intensity of pain, and lateral pathway, reaching brain areas involved with cognitive-emotional aspects of pain. Passive recharge has been suggested to act via modulation of thalamic neurons, which fire in a similar electrical pattern, and thereby modulate activity in various cortical areas including those related to motivational and emotional aspects of pain. The objective of this randomized clinical trial is to assess and compare the effect of active versus passive recharge Burst SCS on a wide spectrum of pain in PSPS Type 2 patients.

Methods

This multicentre randomized clinical trial will take place in 6 Dutch hospitals. PSPS Type 2 patients (n=94) will be randomized into a group receiving either active or passive recharge burst. Following a successful trial period, patients are permanently implanted. Patients complete the Pain Catastrophizing Scale (PCS) (primary outcome at 6 months), Numeric Pain Rating Scale (NRS), Patient Vigilance and Awareness Questionnaire (PVAQ), Hospital Anxiety and Depression Scale (HADS), Quality of Life (EQ-5D), Oswestery Disability Index (ODI), Patient Global Impression of Change (PGIC) and painDETECT questionnaires (secondary outcomes) at baseline, after trial, 1, 3, 6 and 12 months following implantation.

Discussion

The BURST-RAP trial protocol will shed light on possible clinical differences and effectivity of pain relief, including emotional-motivational aspects between active and passive burst SCS in PSPS Type 2 patients.

Trial registration

ClinicalTrials.gov registration: NCT05421273. Registered on 16 June 2022. Netherlands Trial Register NL9194. Registered on 23 January 2021.

Spinal cord stimulation: Beyond pain management

INTRODUCTION

The gate control theory of pain was the starting point of the development of spinal cord stimulation (SCS). We describe the indications for the treatment in pain management and other uses not related to pain.

DEVELOPMENT

There are currently several paradigms for SCS: tonic, burst, and high frequency. The main difference lies in the presence of paraesthesias. SCS is most beneficial for treating neuropathic pain. Patients with failed back surgery syndrome show the best response rates, although a considerable reduction in pain is also observed in patients with complex regional pain syndrome, diabetic neuropathy, radiculopathy, and low back pain without previous surgery. Phantom pain or pain related to cardiovascular or peripheral vascular disease may improve, although there is a lack of robust evidence supporting generalisation of its use. SCS also improves cancer-related pain, although research on this issue is scarce. Non-pain-related indications for SCS are movement disorders, spasticity, and sequelae of spinal cord injury. The main limiting factors for the use of SCS are mechanical complications and the cost of the treatment.

CONCLUSION

In its 50-year history, SCS has progressed enormously. The perfection of hardware and software may improve its effectiveness and reduce the rate of complications. Indications for SCS could include other diseases, and its use could be expanded, if the costs of the technology are reduced.

Burst Spinal Cord Stimulation in the Management of Chronic Pain: Current Perspectives

Over the last several decades, opioid diversion, misuse, and over-prescription have run rampant in the United States. Spinal cord stimulation (SCS) has been FDA approved for treatment for a primary indication of neuropathic limb pain that is resistant to more conservative medical therapy. The disorders qualified for treatment include neuropathic, post-surgical, post-amputation, osteodegenerative, and pain related to vascular disease. Some of the most frequently cited conditions for treatment of SCS include failed back surgery syndrome, complex regional pain syndrome (CRPS) Type I and Type II, and post-herpetic neuralgias. Developments in SCS systems have led to the differentiation between the delivered electromechanical waveform patterns, including tonic, burst, and high-frequency. Burst SCS mitigates traditional paresthesia due to expedited action potential and offers improved pain relief. Burst SCS has been shown in available studies to be non-inferior to the traditional SCS, which can cause pain paresthesia in patients who already have chronic pain. Burst SCS does not seem to cause or need the paresthesia seen in traditional SCS, making SCS not tolerable to patients.

Moreover, some studies suggest that burst SCS may decrease opioid consumption in patients with chronic pain. This can make burst SCS an extremely useful tool in the battle against chronic pain and the raging opioid epidemic. As of now, more research needs to be performed to further delineate the effectiveness and long-term safety of this device.

The future perspectives of psychiatric neurosurgery

The future of psychiatric neurosurgery can be viewed from two separate perspectives: the immediate future and the distant future. Both show promise, but the treatment strategy for mental diseases and the technology utilized during these separate periods will likely differ dramatically. It can be expected that the initial advancements will be built upon progress of neuroimaging and stereotactic targeting while surgical technology becomes adapted to patient-specific symptomatology and structural/functional imaging parameters. This individualized approach has already begun to show significant promise when applied to deep brain stimulation for treatment-resistant depression and obsessive-compulsive disorder. If effectiveness of these strategies is confirmed by well designed, double-blind, placebo-controlled clinical studies, further technological advances will continue into the distant future, and will likely involve precise neuromodulation at the cellular level, perhaps using wireless technology with or without closed-loop design. This approach, being theoretically less invasive and carrying less risk, may ultimately propel psychiatric neurosurgery to the forefront in the treatment algorithm of mental illness. Despite prominent development of non-invasive therapeutic options, such as stereotactic radiosurgery or transcranial magnetic resonance-guided focused ultrasound, chances are there will still be a need in surgical management of patients with most intractable psychiatric conditions.