High‐Dose Spinal Cord Stimulation for Treatment of Chronic Low Back Pain and Leg Pain in Patients With FBSS, 12‐Month Results: A Prospective Pilot Study

Machine learning predicts spinal cord stimulation surgery outcomes and reveals novel neural markers for chronic pain

Spinal cord stimulation (SCS) is a well-accepted therapy for refractory chronic pain. However, predicting responders remain a challenge due to a lack of objective pain biomarkers. The present study applies machine learning to predict which patients will respond to SCS based on intraoperative electroencephalogram (EEG) data and recognized outcome measures. The study included 20 chronic pain patients who were undergoing SCS surgery. During intraoperative monitoring, EEG signals were recorded under SCS OFF (baseline) and ON conditions, including tonic and high density (HD) stimulation. Once spectral EEG features were extracted during offline analysis, principal component analysis (PCA) and a recursive feature elimination approach were used for feature selection. A subset of EEG features, clinical characteristics of the patients and preoperative patient reported outcome measures (PROMs) were used to build a predictive model. Responders and nonresponders were grouped based on 50% reduction in 3-month postoperative Numeric Rating Scale (NRS) scores. The two groups had no statistically significant differences with respect to demographics (including age, diagnosis, and pain location) or PROMs, except for the postoperative NRS (worst pain: p = 0.028; average pain: p < 0.001) and Oswestry Disability Index scores (ODI, p = 0.030). Alpha-theta peak power ratio differed significantly between CP3-CP4 and T3-T4 (p = 0.019), with the lowest activity in CP3-CP4 during tonic stimulation. The decision tree model performed best, achieving 88.2% accuracy, an F1 score of 0.857, and an area under the curve (AUC) of the receiver operating characteristic (ROC)  of 0.879. Our findings suggest that combination of subjective self-reports, intraoperatively obtained EEGs, and well-designed machine learning algorithms might be potentially used to distinguish responders and nonresponders. Machine and deep learning hold enormous potential to predict patient responses to SCS therapy resulting in refined patient selection and improved patient outcomes.

Cylindrical vs Paddle Leads in Spinal Cord Stimulation for the Long-term Treatment of Chronic Pain: A Systematic Review and Meta-analysis

OBJECTIVES

This systematic review compares the long-term efficacy of cylindrical-lead spinal cord stimulation (CL-SCS) vs paddle-lead spinal cord stimulation (Paddle-SCS) for chronic pain management.

MATERIALS AND METHODS

We included prospective and retrospective studies with at least ten patients reporting on the efficacy of either lead type. Primary outcomes were pain score reduction (measured by the visual analog scale [VAS] and numeric rating scale [NRS]) and 50% pain relief after at least 12 months. Secondary outcomes included functional disability and complications, such as lead migration and infection rates. Meta-analyses compared effect sizes, while meta-regression and subgroup analyses addressed heterogeneity.

RESULTS

A total of 96 studies, comprising 7726 patients, met the inclusion criteria. Paddle-SCS demonstrated superior pain reduction, with a standardized mean difference (SMD) of 5.37 (95% CI [5.35, 5.38]) compared with CL-SCS, which had an SMD of 4.09 (95% CI [4.08, 4.10]) on the VAS. However, CL-SCS outperformed Paddle-SCS on the NRS, with SMDs of 4.39 vs 2.35, respectively. For 50% pain relief, Paddle-SCS had a success rate of 41.4%, as opposed to 35.4% for CL-SCS. Paddle-SCS showed a lower migration rate (4.3% vs 7.2% for CL-SCS) but higher infection rates (5.0% vs 3.3%).

CONCLUSIONS

Paddle-SCS offers superior pain reduction (as measured by the VAS) and a lower migration rate, but a higher infection risk compared with CL-SCS. CL-SCS showed better outcomes as measured by the NRS. The choice between Paddle-SCS and CL-SCS should be individualized according to patient-specific factors and treatment goals. Further research with rigorous study designs is needed to provide clearer comparisons between these interventions.

Socioeconomic Determinants of Initiating Neuromodulation for Chronic Pain: A Systematic Review

OBJECTIVES

Neuromodulation is an effective treatment for chronic pain; however, socioeconomic differences may influence decision-making to initiate this therapy. This review investigated potential differences in accessibility of neuromodulation for patients with chronic pain due to socioeconomic determinants.

MATERIALS AND METHODS

Four electronic databases were used for this systematic review: MEDLINE, Embase, Scopus, and Web of Science. Risk of bias was assessed using the modified version of the Downs and Black checklist. The study protocol was prospectively registered on PROSPERO (CRD42023426035).

RESULTS

The initial database search identified a total of 1118 unique studies, of which 36 were eventually included in the systematic review. Of the 36 included studies, six studies reported on education, 24 on employment status, ten on insurance, five on household income, and three on miscellaneous topics. Neuromodulation seems accessible for patients with different education levels and different types of insurance. Additionally, it is not restricted to patients who are (un)employed. When comparing patients who initiated neuromodulation with those who did not, a significantly higher number of patients in the top quartile for education were found in the group without neuromodulation. Regarding insurance, inconclusive evidence was found.

CONCLUSIONS

Although neuromodulation was accessible for patients with varying levels of socioeconomic determinants, disparities were noted. When comparing the socioeconomic profiles of patients who receive neuromodulation and those who do not, education levels differ. Health-related inequality should be carefully monitored in chronic pain management with neuromodulation to ensure that potential disparities do not increase.

Spinal Cord Stimulator Inequities Within the US Military Health System

OBJECTIVES

Although studies have described inequities in spinal cord stimulation (SCS) receipt, there is a lack of information to inform system-level changes to support health care equity. This study evaluated whether Black patients exhaust more treatment options than do White patients, before receiving SCS.

MATERIALS AND METHODS

This retrospective cohort study included claims data of Black and non-Latinx White patients who were active-duty service members or military retirees who received a persistent spinal pain syndrome (PSPS) diagnosis associated with back surgery within the US Military Health System, January 2017 to January 2020 (N = 8753). A generalized linear model examined predictors of SCS receipt within two years of diagnosis, including the interaction between race and number of pain-treatment types received.

RESULTS

In the generalized linear model, Black patients (10.3% [8.7%, 12.0%]) were less likely to receive SCS than were White patients (13.6% [12.7%, 14.6%]) The interaction term was significant; White patients who received zero to three different types of treatments were more likely to receive SCS than were Black patients who received zero to three treatments, whereas Black and White patients who received >three treatments had similar likelihoods of receiving a SCS.

CONCLUSIONS

In a health care system with intended universal access, White patients diagnosed with PSPS tried fewer treatment types before receiving SCS, whereas the number of treatment types tried was not significantly related to SCS receipt in Black patients. Overall, Black patients received SCS less often than did White patients. Findings indicate the need for structured referral pathways, provider evaluation on equity metrics, and top-down support.

Variables associated with nonresponders to high-frequency (10 kHz) spinal cord stimulation

INTRODUCTION

The use of spinal cord stimulation (SCS) therapy to treat chronic pain continues to rise. Optimal patient selection remains one of the most important factors for SCS success. However, despite increased utilization and the existence of general indications, predicting which patients will benefit from neuromodulation remains one of the main challenges for this therapy. Therefore, this study aims to identify the variables that may correlate with nonresponders to high-frequency (10 kHz) SCS to distinguish the subset of patients less likely to benefit from this intervention.

MATERIALS AND METHODS

This was a retrospective single-center observational study of patients who underwent 10 kHz SCS implant. Patients were divided into nonresponders and responders groups. Demographic data and clinical outcomes were collected at baseline and statistical analysis was performed for all continuous and categorical variables between the two groups to calculate statistically significant differences.

RESULTS

The study population comprised of 237 patients, of which 67.51% were responders and 32.49% were nonresponders. There was a statistically significant difference of high levels of kinesiophobia, high self-perceived disability, greater pain intensity, and clinically relevant pain catastrophizing at baseline in the nonresponders compared to the responders. A few variables deemed potentially relevant, such as age, gender, history of spinal surgery, diabetes, alcohol use, tobacco use, psychiatric illness, and opioid utilization at baseline were not statistically significant.

CONCLUSION

Our study is the first in the neuromodulation literature to raise awareness to the association of high levels of kinesiophobia preoperatively in nonresponders to 10 kHz SCS therapy. We also found statistically significant differences with greater pain intensity, higher self-perceived disability, and clinically relevant pain catastrophizing at baseline in the nonresponders relative to responders. It may be appropriate to screen for these factors preoperatively to identify patients who are less likely to respond to SCS. If these modifiable risk factors are present, it might be prudent to consider a pre-rehabilitation program with pain neuroscience education to address these factors prior to SCS therapy, to enhance successful outcomes in neuromodulation.

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

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

MicroRNA-29a Mitigates Laminectomy-Induced Spinal Epidural Fibrosis and Gait Dysregulation by Repressing TGF-β1 and IL-6

Spinal epidural fibrosis is one of the typical features attributable to failed back surgery syndrome, with excessive scar development in the dura and nerve roots. The microRNA-29 family (miR-29s) has been found to act as a fibrogenesis-inhibitory factor that reduces fibrotic matrix overproduction in various tissues. However, the mechanistic basis of miRNA-29a underlying the overabundant fibrotic matrix synthesis in spinal epidural scars post-laminectomy remained elusive. This study revealed that miR-29a attenuated lumbar laminectomy-induced fibrogenic activity, and epidural fibrotic matrix formation was significantly lessened in the transgenic mice (miR-29aTg) as compared with wild-type mice (WT). Moreover, miR-29aTg limits laminectomy-induced damage and has also been demonstrated to detect walking patterns, footprint distribution, and moving activity. Immunohistochemistry staining of epidural tissue showed that miR-29aTg was a remarkably weak signal of IL-6, TGF-β1, and DNA methyltransferase marker, Dnmt3b, compared to the wild-type mice. Taken together, these results have further strengthened the evidence that miR-29a epigenetic regulation reduces fibrotic matrix formation and spinal epidural fibrotic activity in surgery scars to preserve the integrity of the spinal cord core. This study elucidates and highlights the molecular mechanisms that reduce the incidence of spinal epidural fibrosis, eliminating the risk of gait abnormalities and pain associated with laminectomy.

Spinal Cord Stimulation Meets Them All: An Effective Treatment for Different Pain Conditions. Our Experience and Literature Review

IntroductionSpinal Cord Stimulation (SCS) is an emerging minimally invasive technique which uses neuromodulation to manage different forms of intractable pain. SCS is a well-established option for the treatment of various pain conditions, and nowadays, indications are ever increasing.Materials and MethodsIn this study, we present our case series of 49 patients who underwent SCS at our Institution for the treatment of pain from different etiologies, and discuss our 10-year experience in SCS. For the purpose of this study, we also performed a systematic review of current indications and new perspectives in SCS.ResultsAmong our case series, patients were differentiated into two groups upon prior spinal surgery: patients who had undergone prior spinal surgery for back pain were defined as the "FBSS (failed back surgery syndrome) group," instead patient suffering from different types of pain but who had never undergone surgery were defined as the "naive group." As regards clinical response to SCS, 20 patients out of 36 (55.56%) were classified as responders in the FBSS group; in the "naïve" group, 10 patients out of 13 (76.92%) were classified as responders. Among the "not responders" group, several patients suffered from infections.Of the recent literature about SCS, 2124 records were screened and 37 studies were finally included in the qualitative synthesis for our systematic review.DiscussionIn case of FBSS, surgical revision is often associated with a high morbidity and corresponding low rates of success. Unfortunately, patients affected by chronic pain often become refractory to conservative treatments. Spinal Cord Stimulation (SCS) is nowadays considered as an effective therapy for several chronic and neuropathic pain conditions, such as failed back surgery syndrome. As regards the economic impact of SCS, implantation of an SCS system results in short-term costs increase, but the annual cumulative costs decrease during the following years after implantation, when compared to the costs of conventional management. Beyond the application for the treatment of FBSS, SCS has also been used for the treatment of other types of chronic non-oncological pain such as neuropathic pain and chronic back pain ineligible for surgical intervention. This evidence paved the way to establishing the potential role of SCS also for the treatment of oncological pain. However, the effectiveness and relative safety of SCS for cancer-related pain has not yet been adequately established.ConclusionsSpinal Cord Stimulation is a well-established treatment option in for FBSS. Beyond that, SCS has also been used for the treatment of "naive" patients, suffering from other types of chronic, both oncological and non-oncological, medical-refractory pain such as neuropathic pain and chronic back pain ineligible for surgical intervention.

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.

Effectiveness of high dose spinal cord stimulation for non-surgical intractable lumbar radiculopathy - HIDENS Study

OBJECTIVES

Spinal cord stimulation (SCS) is being increasingly used in non-surgical intractable low back pain. This study was designed to evaluate the efficacy of high-dose (HD) SCS utilizing sub-perception stimulation with higher frequency and pulse width in non-surgical predominant low-back pain population at 12 months.

MATERIALS AND METHODS

A total of 20 patients were recruited (280 screened between March 2017 and July 2018) to undergo percutaneous fluoroscopic-guided SCS (Medtronic 8 contact standard leads and Restore^R IPG), with T8 and T9 midline anatomical parallel placement. Sixteen patients completed 12 months follow-up (500 Hz frequency, 500 μs pulse width, and 25% pulse density). Differences in patients' clinical outcome (NRS back, NRS leg, ODI, PGIC, and PSQ) and medication usage (MQS) at 1, 3, and 12 months from the baseline were assessed using non-parametric Wilcoxon paired test.

RESULTS

The mean NRS scores for back pain (baseline 7.53) improved significantly at 1, 3, and 12 months; 2.78 (p < 0.001), 4.45 (p = 0.002), and 3.85 (p = 0.002), respectively. The mean NRS score for leg pain (baseline 6.09) improved significantly at 1 and 3 months; 1.86 (p < 0.001) and 3.13 (p = 0.010), respectively. Mean NRS for leg pain at 12 months was 3.85 (p = 0.057). ODI and sleep demonstrated significant improvement as there was consistent improvement in medication particularly opioid usage (MQS) at 12 months.

CONCLUSIONS

This study demonstrates that anatomical placement of leads with sub-perception HD stimulation could provide effective pain relief in patients who are not candidates for spinal surgery.

High-dose spinal cord stimulation for patients with failed back surgery syndrome: a multicenter effectiveness and prediction study

ABSTRACT

The use of high-dose spinal cord stimulation (HD-SCS) has increased drastically during the past few years, with positive results. However, there remains a deficit of real-world data of the effectiveness of HD-SCS. Therefore, the primary aim was to evaluate the effectiveness of HD-SCS in patients with failed back surgery syndrome (FBSS). The second aim was to develop a prediction model for a holistic responder. One hundred ninety-four patients were recruited to a multicenter real-world registry. Self-reporting outcome variables were evaluated at baseline (before SCS) and at 1, 3, and 12 months of HD-SCS implant. Outcome measures were the mean pain intensity over time, sleep quality, disability, health-related quality of life, and medication use. Besides the effectiveness, logistic regression and decision tree analysis were performed to define a holistic responder (pain intensity reduction, medication reduction, Oswestry disability index reduction, and EQ5D improvement) after 12 months of HD-SCS. Of 185 FBSS patients who underwent a baseline visit, 75.13% had a successful HD trial. At 12 months, 92 patients were still receiving HD-SCS. Both low back and leg pain significantly decreased at 12 months. All outcome measures revealed a significant time-dependent effect from baseline to 12 months. Holistic responders could be predicted with a sensitivity and specificity of 90%. Clinically significant and sustained pain relief over a period of 12 months was achieved with HD-SCS in patients with FBSS. In addition, HD-SCS also achieved an improvement in sleep quality, functionality, and a decrease in pain medication.

Exploration of High and Low Frequency Options for Subperception Spinal Cord Stimulation Using Neural Dosing Parameter Relationships: The HALO Study

OBJECTIVES

Subperception spinal cord stimulation (SCS) is described mostly utilizing waveforms that require high energy. However, the necessity of these waveforms for effective subperception has not been established. We aimed to explore whether effective subperception pain relief can be achieved using frequencies below 1 kHz.

MATERIALS AND METHODS

Thirty chronic pain patients implanted with SCS were enrolled as part of a multicenter, real-world, consecutive, observational case series. An effective stimulation location was determined using a novel electric field shape designed to preferentially modulate dorsal horn elements. Subsequently, programs at lower frequencies (600, 400, 200, 100, 50, and 10 Hz) were provided with pulse-width and amplitude adjusted to optimize response.

RESULTS

All tested frequencies (1 kHz down to 10 Hz) provided effective subperception relief, yielding a mean of 66-72% reduction in back, leg, and overall pain. It was found that to maintain analgesia, as frequency was decreased, the electrical or "neural" dose had to be adjusted according to parameter relationships described herein. With the reduction of frequency, we observed a net reduction of charge-per-second, which enabled energy savings of 74% (200 Hz) and 97% (10 Hz) relative to 1 kHz. Furthermore, pain reduction was sustained out to one year, with 85% of patients reporting a preference for frequencies of 400 Hz or below.

CONCLUSIONS

We have derived an electric field configuration and, along with previous learnings in the kHz range, a set of neural dosing parameter relationships (10-10,000 Hz), which enable the expansion of effective subperception SCS to low frequency and achieve major energy savings.

Long-Term Efficacy of a Novel Spinal Cord Stimulation Clinical Workflow Using Kilohertz Stimulation: Twelve-Month Results From the Vectors Study

BACKGROUND AND OBJECTIVES

Multiple variables play a role in spinal cord stimulation (SCS) treatment outcomes, including patient anatomy, pain pattern, lead location, stimulation parameters, and so on. A wide range of stimulation parameters are considered safe and on-label, and as a result a growing number of new frequencies and frequency-combinations are being incorporated into standard practice. A standardized approach to therapy delivery may provide more consistent outcomes for more patients. The Vectors study evaluated whether there is significant sustained improvement in pain and functional outcomes when therapy is delivered using a standardized approach.

MATERIALS AND METHODS

Vectors, a post-market, single-arm study evaluated the safety and efficacy of SCS with an implantable neurostimulator starting with 1 kHz stimulation, targeting the T9-T10 disc space following paresthesia mapping. Subjects with chronic intractable low back and leg pain (visual analogue scale [VAS] ≥ 50 mm) were enrolled. The primary endpoint was change in overall pain (VAS) at the three-month visit compared to baseline. Subjects were followed through 12 months. Secondary endpoints included changes in low back and leg pain, quality of life (European Quality of Life - Five Dimensions, EQ-5D-5L), disability (Oswestry Disability Index, ODI), individual subject goals, and subject satisfaction.

RESULTS

There was a significant reduction in overall pain (VAS; 45.4 mm) through the three-month visit, which was sustained through 12 months. At 12 months, 79% of subjects had ≥50% improvement in at least one pain domain (overall, lowback or leg) with 85% of subjects reporting therapy satisfaction. There was a decrease in disability and an improvement in quality of life with 70% of subjects achieving a personal activity goal by the three-month visit.

CONCLUSIONS

Long-term pain relief and improvement in quality of life and function were achieved when following a standardized workflow.

CLINICAL TRIAL REGISTRATION

The Clinicaltrials.gov registration number for the study is NCT03345472.

Long-term quality of life and work status after high-dose spinal cord stimulation in patients with failed back surgery syndrome: a secondary analysis of real-world data

OBJECTIVE

In recent years, the use of high-dose spinal cord stimulation (HD-SCS) as a treatment option for patients with failed back surgery syndrome (FBSS) has drastically increased. However, to the authors' knowledge a thorough evaluation of health-related quality of life (HRQOL) and work status in these patients has not yet been performed. Moreover, it is unclear whether patients who are treated with HD-SCS can regain the same levels of HRQOL as the general population. Therefore, the aims of this study were to compare the HRQOL of patients who receive HD-SCS to HRQOL values in an age- and sex-adjusted population without FBSS and to evaluate work status in patients who are receiving HD-SCS.

METHODS

HRQOL, measured with the 3-level EQ-5D (EQ-5D-3L), and work status were evaluated in 185 FBSS patients at baseline (i.e., before SCS) and at 1, 3, and 12 months of treatment with HD-SCS. Difference scores in utility values between patients and an age- and sex-adjusted normal population were calculated. One-sample Wilcoxon tests were used to assess the EQ-5D-3L difference scores. Mixed models were used to evaluate the evolution over time in EQ-5D-3L utility scores and EQ-5D visual analog scale (VAS) scores in patients and matched controls. Quality-adjusted life-years (QALYs) were calculated using the area under the curve method.

RESULTS

An overall significant increase in EQ-5D-3L utility scores and EQ-5D VAS scores was found over time in the patient group. Wilcoxon tests indicated that the difference scores in utility values between patients and the normal population were significantly different from zero at all time points. The median incremental QALY after 12 months of HD-SCS was 0.228 (Q1-Q3: 0.005-0.487) in comparison to continued conservative treatment. At 12 months, 13.75% of patients resumed work.

CONCLUSIONS

HD-SCS may lead to significantly increased HRQOL at 12 months in patients with FBSS. Despite the increase, reaching the HRQOL level of matched controls was not achieved. Only a limited number of patients were able to return to work. This finding indicates that specialized programs to enhance return to work may be beneficial for patients undergoing SCS.

High-Dose Spinal Cord Stimulation Reduces Long-Term Pain Medication Use in Patients With Failed Back Surgery Syndrome Who Obtained at Least 50% Pain Intensity and Medication Reduction During a Trial Period: A Registry-Based Cohort Study

OBJECTIVES

High-dose spinal cord stimulation (HD-SCS) revealed positive results for obtaining pain relief in patients with failed back surgery syndrome (FBSS). However, it is less clear whether HD-SCS also is able to reduce pain medication use. The aim of this registry-based cohort study is to explore the impact of HD-SCS on pain medication use in FBSS patients.

MATERIALS AND METHODS

Data from the Discover registry was used in which the effectiveness of HD-SCS was explored in neurostimulation-naïve FBSS patients as well as in rescue patients. All neurostimulation-naïve FBSS patients positively responded to a four-week SCS trial period in which at least 50% pain relief and 50% medication reduction were obtained. Medication use was measured with the Medication Quantification Scale III (MQS) in 259 patients at baseline and at 1, 3, and 12 months of HD-SCS. Additionally, defined daily doses (DDD) and morphine milligram equivalents (MME) were calculated as well.

RESULTS

One hundred thirty patients reached the visit at 12 months. In neurostimulation-naïve patients, a statistically significant decrease in MQS (χ² = 62.92, p < 0.001), DDD (χ² = 11.47, p = 0.009), and MME (χ² = 21.55, p < 0.001) was found. In rescue patients, no statistically significant improvements were found. In both patient groups, statistically significant reductions in the proportion of patients on high-risk MME doses ≥90 were found over time. At the intraindividual level, positive correlations were found between MSQ scores and pain intensity for back (r = 0.56, r = 0.31, p < 0.001) and leg pain (r = 0.61, r = 0.22, p < 0.001) in neurostimulation-naïve and rescue patients, respectively.

CONCLUSIONS

Registry data on HD-SCS in FBSS patients revealed a statistically significant and sustained decrease in pain medication use, not only on opioids, but also on anti-neuropathic agents in neurostimulation-naïve patients, who positively responded to an SCS trial period with at least 50% pain relief and 50% pain medication decrease, but not in rescue patients.

The Added Value of High Dose Spinal Cord Stimulation in Patients with Failed Back Surgery Syndrome after Conversion from Standard Spinal Cord Stimulation

Patients with Failed Back Surgery Syndrome (FBSS) report a considerably lower health- related quality of life (HRQoL), compared to the general population. Spinal cord stimulation (SCS) is an effective treatment to offer pain relief in those patients. Despite initial treatment success of SCS, its effect sometimes wears off over time. This study investigates the added value of high dose SCS (HD-SCS) in patients with unsatisfactory conventional SCS, from a quality of life perspective. Seventy-eight FBSS patients who were treated with conventional SCS that failed to provide pain relief, were recruited in 15 centers. HRQoL was assessed before converting to HD-SCS (baseline) and three times after converting to HD-SCS using the EuroQol-5D-3L. Quality adjusted life years (QALY) were calculated and compared with conventional SCS. An overall significant increase over time was seen in utility values of the EQ5D-3L, as the mean value at baseline 0.283 (±0.21) increased to 0.452 (±0.29) at 12 months of HD-SCS. This average increase in utility coincides with an average increase of 0.153 (±0.24) QALY’s in comparison to continued conventional SCS. Besides the potential of HD-SCS to salvage patients with failed responses to conventional SCS, this treatment seems to be a more efficient treatment than conventional SCS.

The Long-Term Response to High-Dose Spinal Cord Stimulation in Patients With Failed Back Surgery Syndrome After Conversion From Standard Spinal Cord Stimulation: An Effectiveness and Prediction Study

OBJECTIVES

Spinal cord stimulation (SCS) is nowadays available with several stimulation paradigms. New paradigms, such as high dose (HD-)SCS, have shown the possibility to salvage patients who lost their initial pain relief. The first aim of this study is to evaluate the effectiveness of HD-SCS after conversion from standard SCS. The second aim is to develop a model for prediction of long-term response of HD-SCS after unsatisfactory standard SCS.

MATERIALS AND METHODS

Seventy-eight patients with failed back surgery syndrome (FBSS) who are treated with standard SCS were enrolled in the study. Self-reporting questionnaires and outcomes were assessed before conversion and at 1, 3, and 12 months of HD-SCS. Longitudinal mixed models were used to determine the effectiveness of HD-SCS. Logistic regression and classification and decision tree analyses were performed to predict responders (NRS decrease ≥2/10) after 12 months of HD-SCS.

RESULTS

Significant time effects were found for both low back and leg pain responders, suggesting the effectiveness of HD-SCS after conversion. Logistic regression models revealed the importance of pain intensity scores, medication use, paresthesia coverage (for back pain) and EQ5D (for leg pain) as predictors for being a responder after 12 months of HD-SCS.

CONCLUSIONS

Converting patients with unsatisfactory responses from standard SCS to HD-SCS may be an effective strategy to obtain and maintain pain relief in a challenging subgroup of patients with FBSS refractory to standard SCS. The prediction models may guide clinicians in their decision making when considering conversion to HD-SCS in patients with FBSS experiencing inadequate response to standard SCS.

The influence of High Dose Spinal Cord Stimulation on the descending pain modulatory system in patients with failed back surgery syndrome

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For the first time, the influence of HD-SCS on the descending pathways was tested.

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rsfMRI and functional connectivity were used to evaluate this a priori hypothesis.

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HD-SCS does influence the descending pain modulatory system.