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

An Evidence-Based Consensus for the Use of Neurostimulation for the Treatment of Non-Surgical Low Back Pain: The NEURON Group

Introduction

The use of electrical neuromodulation has often been limited to those with previous back surgery, peripheral neuropathy, and complex regional pain syndrome. Many patients with severe intractable low back pain were thought to be candidates for spinal cord stimulation (SCS), dorsal root ganglion stimulation, or peripheral nerve stimulation but did not meet the criteria. Recently, additional high-level data has supported the use of SCS in non-surgical low back pain (NSLBP), and United States Food and Drug Administration approval has been granted. The American Society of Pain and Neuroscience (ASPN) executive committee realized an unmet need to develop criteria for patient selection for this specific patient population. This is a NEURON project (neuroscience, education, utilization, risk mitigation, optimal outcomes, and neuromodulation), a living guideline for evolving therapies and indications, and is focused on the use of neuraxial stimulation for the treatment of refractory pain.

Methods

After board approval, the society accepted nominees for the project, with an emphasis on experience, publication, research, and diversity. The team created an outline for discussion, chose a grading system based on published guidelines, and created consensus points.

Results

The evidence led to several consensus points to best guide patient selection based on the level of evidence and expert opinion. The results will lead to improved safety and efficacy in implanted patients, and to a new standard for best practices.

Conclusion

The selection of patients for implantation in those who have NSLBP should be based on published literature, best practice, and expert opinion. This NEURON project will allow for regular updates to create a living guideline that will allow for better assimilation of information to improve safety and efficacy going forward.

Development and Feasibility Study of a Triage Tool for Early Referral to Spinal Cord Stimulation for Patients With Chronic Low Back and Leg Pain

BACKGROUND

In recent years, delayed elective care and growing waiting lists increasingly resulted in postponed surgeries for patients with chronic back and leg pain.

OBJECTIVE

To develop, implement, and evaluate the feasibility of a triage tool for patients with chronic back and/or leg pain to identify those eligible for referral to spinal cord stimulation (SCS) consultation.

METHODS

A triage tool was developed, based on Dutch SCS guidelines, literature review and expert panel consultation. The triage process was detected and implemented in collaboration with a multidisciplinary team, prior to first orthopaedic consultation. Feasibility, reliability and predictive accuracy were analysed as part of the evaluation of the triage tool.

RESULTS

The triage indicators included: Pain location (leg/mixed), DN4 > 3, pain duration ≥ 3 months, leg pain ≥ back pain and NPRS leg pain ≥ 5. The triage tool was applied on patients on the orthopaedic waiting list, followed by a full orthopaedic review if they were not excluded. A total of 1025 orthopaedic patients with chronic back and leg pain were assessed with the triage tool. The triage tool was evaluated as feasible (mean System Usability Score 74.2 [SD 11.5]), reliable (inter-rater reliability [Fleiss' Kappa 0.79], intra-rater reliability [Cohen's Kappa 0.89]) and accurate (sensitivity [100%], specificity [98.8%], positive predictive value [40%] and negative predictive value [100%]).

CONCLUSION

Early triage of potential SCS candidates potentially supports rapid and appropriate care allocation, shortens waiting list time and improves clinical outcomes. Future research should explore strategies to optimise the tool's performance in identifying patients most likely to benefit from SCS therapy.

SIGNIFICANCE

A novel triage tool was developed to identify patients with chronic back and leg pain for an early referral to SCS. This tool, evaluated for feasibility, reliability, and predictive accuracy, shows promise in reducing waiting times and improving patient selection. It can be a prelude to the further development of decision support for SCS and an acceleration in the care process for SCS candidates.

The Opinion of Healthcare Professionals About a Proposed European Registry of Neuromodulation for Chronic Pain: An Online Survey

INTRODUCTION

During the last decade, the complementary value of real-world data (through registries or medical records) and data from randomized clinical trials has been recognized as increasingly important. In the field of neuromodulation, only a few industry-independent nationwide neuromodulation registries are available. The interest in creating a European registry has increased but without a successful result. The goal of this online survey is to gain further insights into the need for and burden of a European registry for neuromodulation.

MATERIALS AND METHODS

An online survey was developed and distributed during the 3rd Joint Congress of the International Neuromodulation Society European Chapters in September 2023 (Hamburg, Germany). Healthcare professionals were asked to indicate the need for a European registry, the items that should be collected, and the restrictions to access of a European registry.

RESULTS

In total, 125 respondents opened the link to the survey, of whom 104 completed (at least partly) the survey. Of the 104 responses, 91% indicated that there is a need for a European registry, whereas 6% indicated there is no need. The main reasons for establishing a registry on a European level were the possibility of collecting real-world evidence (84%), the potential to collect big data from European patients (82%), to evaluate safety in neuromodulation (70%), and the possibility of reporting yearly on European activity in neuromodulation (51%). Indications for neuromodulation, patient characteristics, and follow-up assessments were most often stated as items that should be collected. Access should not only be granted to implanters but also to nurses, the assessment team, and other physicians, as agreed on by 64%, 52%, and 51%, respectively.

DISCUSSION

More than 90% of the respondents believed that a European registry for neuromodulation is needed, mainly to obtain real-world (big) data about the effectiveness and safety of this therapy. This survey clearly pointed to the need for a European registry for which it seems key to ensure financial and logistical support, in addition to in-depth legal guidance in developing this registry.

A digital tool for multidimensional assessment and prediction of treatment effectiveness in chronic pain management

Given the multidimensional aspect of pain, the assessment of treatment efficacy is challenging. The prospective observational multicenter PREDIBACK study aimed to assess, compare, and predict the effectiveness of different treatments for persistent spinal pain syndrome type 2 (PSPS-T2) using a digital tool and the Multidimensional Clinical Response Index (MCRI) including pain intensity, functional disability, quality of life, anxiety and depression, and pain surface. Results indicated that neurostimulation was the most effective treatment at 3-, 6-, 9-, and 12-month follow-up compared to baseline, leading to significant improvements in pain, function, and quality of life, whereas optimized medical management (OMM) and spinal reoperation showed no significant benefits. Additionally, the study identified pain surface, BMI, and smoking status as predictors of treatment outcomes. These findings highlight the potential of digital medicine to improve patient care by providing data-driven insights and personalized treatment recommendations for PSPS-T2.

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.

Differential target multiplexed spinal cord stimulation in patients with Persistent Spinal Pain Syndrome Type II: a study protocol for a 12-month multicentre cohort study (DETECT)

INTRODUCTION

Differential target multiplexed spinal cord stimulation (DTM SCS) is a new stimulation paradigm for chronic pain management with the aim of modulating glial cells and neurons in order to rebalance their interactions. Animal studies revealed positive effects of this type of stimulation; however, studies in humans are still scarce, pointing towards the need for an evaluation of the effectiveness and safety of DTM SCS in clinical settings. Furthermore, the differential target multiplexed (DTM) algorithm consists of a combination of several programmes, which will presumably consume more energy from the spinal cord stimulation (SCS) battery. Therefore, the objective of DETECT is to investigate the feasibility, effectiveness and safety of DTM SCS in patients with Persistent Spinal Pain Syndrome Type II through a longitudinal cohort study.

METHODS AND ANALYSIS

DETECT is a prospective multicentre cohort study (n≥250) with a follow-up until 12 months after receiving DTM SCS. The study initiated in October 2021 and is currently still recruiting patients. Self-reporting outcome variables were evaluated at baseline (before SCS) and at 1, 6 and 12 months of DTM SCS. The primary effectiveness endpoint is overall pain intensity, measured with the visual analogue scale. Secondary effectiveness outcome measures are back pain intensity, leg pain intensity, disability, health-related quality of life, pain medication use, functional disability, clinical holistic responder status, self-management, impression of change, work status, pain catastrophising, symptoms of central sensitisation, anxiety, depression and healthcare utilisation. Time spent in different body postures and SCS stimulation parameters will be read out from the pulse generator. The prevalence of technical issues, recharge frequency, (serious) adverse events and the proportion of successful DTM trials will be collected as well. Longitudinal mixed models will be calculated to evaluate the effectiveness of DTM SCS over time.

ETHICS AND DISSEMINATION

The study protocol was approved by the central Ethics Committee of the Universitair Ziekenhuis Brussel, Vrije Universiteit Brussel (B.U.N.1432021000563) and the Ethics Committees of each participating centre. Research findings will be disseminated to key stakeholders through peer-reviewed publications in scientific journals and presentations to clinical audiences.

TRIAL REGISTRATION NUMBER

NCT05068011.

Pain medication tapering for patients with Persistent Spinal Pain Syndrome Type II, treated with Spinal Cord Stimulation: A RCT-study protocol of the PIANISSIMO study

BACKGROUND

Spinal Cord Stimulation (SCS) may provide pain relief in patients with therapy-refractory Persistent Spinal Pain Syndrome Type II (PSPS-T2). Despite the evidence that SCS can reduce disability and reduce pain medication usage, only 25% of the patients is able to completely omit pain medication usage after 12 months of SCS. To tackle the high burden of patients who consume a lot of pain medication, tapering programs could be initiated before starting a trajectory with SCS. The current objective is to examine whether a pain medication tapering program before SCS alters disability in PSPS-T2 patients compared to no tapering program.

METHODS AND DESIGN

A three-arm, parallel-group multicenter randomized controlled trial will be conducted including 195 patients who will be randomized (1:1:1) to either (a) a standardized pain medication tapering program, (b) a personalized pain medication tapering program, or (c) no tapering program before SCS implantation, all with a follow-up period until 12 months after implantation. The primary outcome is disability. The secondary outcomes are pain intensity, health-related quality of life, participation, domains affected by substance use, anxiety and depression, medication usage, psychological constructs, sleep, symptoms of central sensitization, and healthcare expenditure.

DISCUSSION

Within the PIANISSIMO project we propose a way to reduce the risks of adverse events, medication-induced hyperalgesia, tolerance, and dependence by providing pain medication tapering before SCS. Due to the lack of a commonly accepted in-hospital tapering approach, two different tapering programs will be evaluated in this study. If pain medication tapering programs are deemed to be more effective than no tapering on disability, this would add to the evidence towards an improved patient-centered care model in this patient group and set a clear path to advocate for pain medication tapering before SCS as the new standard treatment guideline for these patients.

TRIAL REGISTRATION

ClinicalTrials.gov NCT05861609. Registered on May 17, 2023.

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.

Opinions of Health Care Providers About Neuromodulation for Pain: Results of an Online Survey at the 2nd Joint Congress of the International Neuromodulation Society European Chapters

INTRODUCTION

Neuromodulation for pain has been successfully applied for decades, in that the goals and expectations that patients aim to achieve are clearly described. Nevertheless, the point of view of health care providers is less clear. Therefore, this study aimed to explore the goals, expectations, and definition of success for neuromodulation for pain according to health care providers.

MATERIALS AND METHODS

An online survey was developed and spread at the 2nd Joint Congress of the International Neuromodulation Society (INS) European Chapters in September 2021 in Paris. Respondents were asked 1) to select the goals to treat patients with neuromodulation for pain, 2) to indicate factors that they expect to change according to neuromodulation for pain, and 3) to provide their definition of success of neuromodulation for pain.

RESULTS

We approached 101 respondents, of whom 88 health care providers at least partly completed the survey. Increasing mobility/functionality (26.7%), decreasing pain intensity (24.5%), and decreasing medication use (16.6%) were the most frequently reported goals of neuromodulation. The same top three variables were selected as factors that health care providers expected to change. For the definition of success, quality of life of patients outranked other definitions. Other highly ranked definitions, in descending order, were obtaining pain relief, increasing functionality, and increasing patient satisfaction.

DISCUSSION

Goals and expectations of health care providers are not completely in line with previously explored goals of patients that are related to pain relief and improving walking abilities. Health care providers seem to put a high emphasis on the quality of life of the patient when evaluating the success of neuromodulation, which is not completely aligned with the currently used reimbursement rules that are mainly focusing on pain relief instead of incorporating health-related quality of life.

CLINICAL TRIAL REGISTRATION

The Clinicaltrials.gov registration number for the study is NCT05013840.

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.

Physical functioning following spinal cord stimulation: a systematic review and meta-analysis

BACKGROUND

Spinal cord stimulation (SCS) has emerged as an important treatment for chronic pain disorders. While there is evidence supporting improvement in pain intensity with SCS therapy, efforts to synthesize the evidence on physical functioning are lacking.

OBJECTIVE

The primary objective of this meta-analysis was to assess long-term physical function following 12 months of SCS for chronic back pain.

EVIDENCE REVIEW

PubMed, EMBASE, Scopus, and CENTRAL databases were searched for original peer-reviewed publications investigating physical function following SCS. The primary outcome was physical function at 12 months following SCS therapy for chronic back pain compared with baseline. A random effects model with an inverse variable method was used. The Grading of Recommendation, Assessment, Development, and Evaluation (GRADE) framework was used to determine the certainty of evidence.

FINDINGS

A total of 518 studies were screened, of which 36 were included. Twenty-two studies were pooled in the meta-analysis. There was a significant reduction in Oswestry Disability Index (ODI) scores at all time frames up to 24 months following implantation. Pooled results revealed significant improvement in ODI scores at 12 months with a mean difference of -17.00% (95% CI -23.07 to -10.94, p<0.001). There was a very low certainty of evidence in this finding as per the GRADE framework. There was no significant difference in subgroup analyses based on study design (randomised controlled trials (RCTs) vs non-RCTs), study funding, or stimulation type.

CONCLUSION

This meta-analysis highlights significant improvements in physical function after SCS therapy. However, this finding was limited by a very low GRADE certainty of evidence and high heterogeneity.

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.

Proportion of clinical holistic responders in patients with persistent spinal pain syndrome type II treated by subthreshold spinal cord stimulation compared to best medical treatment: a study protocol for a multicentric randomised controlled trial (TRADITION)

BACKGROUND

Integrating information on bodily functions, pain intensity and quality of life into one composite measure of a holistic responder has recently been proposed as a useful method to evaluate treatment efficacy of spinal cord stimulation (SCS) in patients with therapy-refractory persistent spinal pain syndrome type II (PSPS-T2). Previous studies already demonstrated the efficacy of standard SCS over best medical treatment (BMT) and the superiority of new subthreshold (i.e. paresthesia free) SCS paradigms compared to standard SCS. Nevertheless, the efficacy of subthreshold SCS compared to BMT has not yet been investigated in patients with PSPS-T2, neither with unidimensional outcomes nor with a composite measure. The current objective is to examine whether subthreshold SCS, compared to BMT, provided to patients with PSPS-T2 results in a different proportion of clinical holistic responders (as composite measure) at 6 months.

METHODS

A two-arm multicentre randomised controlled trial will be conducted whereby 114 patients will be randomised (1:1) to (a) BMT or (b) paresthesia-free SCS. After a follow-up period of 6 months (primary time endpoint), patients receive the opportunity to cross over towards the other treatment group. The primary outcome is the proportion of clinical holistic responders at 6 months (i.e. a composite measure of pain intensity, medication, disability, health-related quality of life and patient satisfaction). The secondary outcomes are work status, self-management, anxiety, depression and healthcare expenditure.

DISCUSSION

Within the TRADITION project, we propose to shift the focus from a unidimensional outcome measure towards a composite measure as primary outcome measure to evaluate the efficacy of currently used subthreshold SCS paradigms. The lack of methodologically rigorous trials exploring the clinical efficacy and socio-economic consequences of subthreshold SCS paradigms is pressing, especially in light of the growing burden of PSPS-T2 on the society.

TRIAL REGISTRATION

ClinicalTrials.gov NCT05169047. Registered on December 23, 2021.

The Association Between Bodily Functions and Cognitive/Emotional Factors in Patients With Chronic Pain Treated With Neuromodulation: A Systematic Review and Meta-Analyses

OBJECTIVES

To date, pain relief in general continues to be the most prominent outcome measurement in daily routine care and clinical research. Nevertheless, the awareness of a shift toward more functional outcomes and/or emotional and cognitive outcomes has been raised. The interplay between bodily functions (such as pain intensity) and emotional or cognitive factors, however, has not yet been fully elucidated. The aim of this study was to systematically review the evidence for associations between bodily functions and cognitive and emotional factors in patients with chronic pain who are treated with neuromodulation.

MATERIALS AND METHODS

Four data bases were consulted for this systematic literature review: PubMed, Web of Science, Scopus, and Embase. The Downs and Black Checklist (modified) was used to assess the risk of bias. The study protocol was prospectively registered at the International prospective register of systematic reviews (PROSPERO, CRD42021226803). If two or more studies reported correlation coefficients for a specific association, a meta-analysis based on correlation coefficients was performed for that specific association.

RESULTS

The initial data base search identified a total of 1432 studies, of which 19 studies were eventually included in the systematic review. Evidence was found for two associations: 1) a positive correlation between pain intensity and anxiety (r = 0.42; 95% CI, 0.34 to 0.50) and 2) a positive correlation between pain intensity and depression (r = 0.32; 95% CI, 0.10 to 0.51). The association between pain intensity and catastrophizing was not statistically significant (r = 0.23; 95% CI, -0.36 to 0.69).

CONCLUSIONS

On the basis of the associations between pain intensity and anxiety/depression, a biopsychosocial approach might be the most suitable in clinical practice to properly address all aspects of the International Classification of Functioning, Disability, and Health framework in patients who are treated with neuromodulation.

Spinal Cord Stimulation-Naïve Patients vs Patients With Failed Previous Experiences With Standard Spinal Cord Stimulation: Two Distinct Entities or One Population?

INTRODUCTION

Nowadays, the success of spinal cord stimulation (SCS) is evaluated separately in patients who have previous experiences with standard SCS and in SCS-naïve patients. Nevertheless, it is yet to be evaluated whether both patient groups are effectively distinct patient groups. Therefore, the aims of this study are twofold: 1) Are there clusters in the data to distinguish between both patient groups? 2) Can we discriminate both patient groups based on routinely collected clinical parameters?

MATERIALS AND METHODS

Baseline data from the Discover study were used, in which 263 patients with persistent spinal pain syndrome type 2 were included (185 neurostimulation-naïve patients and 78 patients with previous SCS experience). Pain intensity scores for low back and leg pain, functional disability, medication use, and health-related quality of life utility scores were used in the analysis. Model-based clustering was performed on standardized data. Discriminant analysis was performed with linear and quadratic discriminant analysis, with leave-one-out cross-validation to evaluate model performance.

RESULTS

Model-based clustering revealed two different clusters in the data. None of the clusters clearly separated SCS-naïve patients from patients with previous SCS experience. Linear discriminant analysis resulted in a leave-one-out cross-validation error rate of 30.0% to discriminate between both patient groups, based on routinely collected clinical parameters.

CONCLUSIONS

Clustering analysis did not result in clusters that separate SCS-naïve patients from patients with previous SCS experience. This may suggest that both patient groups should not be considered as two different patient groups when comparing them on routine clinical parameters, with potentially profound implications for research and clinical settings.

CLINICAL TRIAL REGISTRATION

The Clinicaltrials.gov registration number for the Discover study is NCT02787265.

Gradation of Clinical Holistic Response as New Composite Outcome to Evaluate Success in Spinal Cord Stimulation Studies for Pain

INTRODUCTION

The most prominent outcome measurement in the field of neuromodulation is pain relief. Nevertheless, the number of studies that rely on composite outcomes has increased. The aims of this study are twofold: (1) to evaluate which measures are important to include in a composite outcome and (2) to develop this new composite outcome to evaluate the degree of being a clinical holistic responder with a corresponding minimal clinical important difference (MCID).

MATERIALS AND METHODS

Data from patients with persistent spinal pain syndrome type 2 treated with High-Dose Spinal Cord Stimulation (HD-SCS) were used. Pain intensity for low back and leg pain, disability, health-related quality of life, medication use, and patient satisfaction were measured at baseline and after 12 months of HD-SCS. Exploratory and Confirmatory Factor Analyses were used to evaluate which measures should be included in the composite outcome. Anchor-based and distribution-based methods were applied to determine the MCID of the newly developed outcome measurement.

RESULTS

A three-factor model was the most appropriate for this data set, in which leg pain intensity, EQ5D VAS, and disability had the largest loading on these factors. A clinical holistic outcome was created with a total score ranging from 0 (=better [no pain, no disability, and perfect health status]) to 300 (=worse [maximal pain, maximal disability, and worst health status]). The MCID value based on an absolute change score from baseline up to 12 months of HD-SCS was 87.97. When calculating with percentage changes, a MCID value of 48.4% was revealed.

CONCLUSIONS

This new composite outcome evaluating the degree of deviation from being a holistic responder is a step toward a meaningful, overall outcome assessment for patients who are treated with SCS. Further studies to evaluate the psychometric properties and the generalizability toward other patient populations still need to be performed.

Cross-Country Differences in Pain Medication Before and After Spinal Cord Stimulation: A Pooled Analysis of Individual Patient Data From Two Prospective Studies in the United Kingdom and Belgium

OBJECTIVES

Spinal cord stimulation (SCS) can reduce the need for opioids; however, the influence on the full spectrum of pain medication is less known. The aims of this study were to explore general prescription practices for patients scheduled for SCS, potential differences in prescriptions between Belgium and United Kingdom, and the influence of SCS on pain medication.

MATERIALS AND METHODS

Individual patient data from the TRIAL-STIM study in the United Kingdom and DISCOVER in Belgium were pooled. Medication use was collected before SCS and three months after SCS from 180 chronic pain patients. The Medication Quantification Scale III (MQS) was used to calculate a total score for medication use, as well as subscores for several classes. Differences in prescription practices between United Kingdom and Belgium were evaluated with two-sided Wilcoxon tests. To evaluate differences in medication use after three months of SCS between United Kingdom and Belgium, Tweedie-generalized linear models were calculated.

RESULTS

There was a statistically significant difference (-6.40 [95% CI from -3.40 to -9.10]) between the median total MQS score in United Kingdom and Belgium before SCS. Additionally, a significant difference was found for nonsteroidal anti-inflammatory drugs (NSAIDs) (-3.40 [95% CI -3.40 to -6.80]), neuropathic agents (-2.30 [95% CI -0.40 to -3.80]), and benzodiazepines (1.83e-05 [95% CI 2.64-05 to 7.45-05]) between United Kingdom and Belgium, before SCS. Tweedie-generalized models revealed a statistically significant interaction between country and time for MQS, neuropathic agents, and opioids.

CONCLUSIONS

Our combined analysis revealed differences in prescription practice in patients scheduled for SCS implantation between Belgium and United Kingdom. NSAIDs and neuropathic mood agents are more frequently used in the United Kingdom, presumably due to easier access to repeat prescriptions and over the counter medications. After three months of SCS, a decrease in medication use is observed in both countries, with higher reductions in Belgium, presumably due to strict regulations concerning reimbursement criteria.

Personalised rehabilitation to improve return to work in patients with persistent spinal pain syndrome type II after spinal cord stimulation implantation: a study protocol for a 12-month randomised controlled trial-the OPERA study

BACKGROUND

For patients with therapy-refractory persistent spinal pain syndrome type II (PSPS-T2), spinal cord stimulation (SCS) may serve as an effective minimally invasive treatment. Despite the evidence that SCS can improve return to work (RTW), only 9.5 to 14% of patients implanted with SCS are effectively capable of returning to work. Thus, it seems that current post-operative interventions are not effective for achieving RTW after SCS implantation in clinical practice. The current objective is to examine whether a personalised biopsychosocial rehabilitation programme specifically targeting RTW alters the work ability in PSPS-T2 patients after SCS implantation compared to usual care.

METHODS

A two-arm, parallel-group multicentre randomised controlled trial will be conducted including 112 patients who will be randomised (1:1) to either (a) a personalised biopsychosocial RTW rehabilitation programme of 14 weeks or (b) a usual care arm, both with a follow-up period until 12 months after the intervention. The primary outcome is work ability. The secondary outcomes are work status and participation, pain intensity, health-related quality of life, physical activity and functional disability, functional capacities, sleep quality, kinesiophobia, self-management, anxiety, depression and healthcare expenditure.

DISCUSSION

Within the OPERA project, we propose a multidisciplinary personalised biopsychosocial rehabilitation programme specifically targeting RTW for patients implanted with SCS, to tackle the high socio-economic burden of patients that are not re-entering the labour market. The awareness is growing that the burden of PSPS-T2 on our society is expected to increase over time due to the annual increase of spinal surgeries. However, innovative and methodologically rigorous trials exploring the potential to decrease the socio-economic burden when patients initiate a trajectory with SCS are essentially lacking.

TRIAL REGISTRATION

ClinicalTrials.gov NCT05269212. Registered on 7 March 2022.

Health-related quality of life in persons post-COVID-19 infection in comparison to normative controls and chronic pain patients

The Coronavirus disease 2019 (COVID-19) pandemic exerted a tremendous pressure on the healthcare system, people's social life, mental health and financial status with profound implications for the general population. The exact impact of the pandemic on the overall physical, mental and social wellbeing of COVID-19 infection survivors on the long term has not yet been explored in a thorough way. Based on the reporting of persistent pain, fatigue and dyspnea symptoms by these survivors, it is our hypothesis that their quality of life will be extremely impacted, as is observed in patients with chronic pain. Therefore, the first aim of this study was to perform an in-depth evaluation of the quality of life of post-COVID-19 infected persons. The second aim was to compare the quality of life of these persons with a normative population and with patients with chronic pain. Health-related quality of life, as a measure for a person's overall physical, mental, and social wellbeing, was measured with the 3-level EQ5D in 547 post-COVID-19 infected persons. These data were compared to reference data from normal population records for Belgium and to data from patients with chronic pain after spinal surgery with two-way analyses of variance. In total, 89.58% of the post-COVID-19 infected persons reported pain/discomfort and 82.45% indicated limitations when performing usual activities, when evaluated 287 days (SD: 150) after the infection. Self-care was preserved in most post-COVID-19 persons, whereby only 13.16% indicated problems. The mean EQ5D-3L index score was 0.57 (SD: 0.23) and EQ5D VAS mean score was 56.6 (SD: 18.2). The mean index score for the normative population was significantly higher than for COVID-19 infected persons [mean difference of 0.31 (95% from 0.29 to 0.33), p < 0.01] while the mean score of chronic pain patients was significantly lower than the score of COVID-19 infected persons [mean difference of -0.31 (95% from -0.29 to -0.33), p < 0.01]. Compared to age-and sex adjusted reference data, health-related quality of life of persons with long COVID is severely impacted. In relation to patients with chronic pain after spinal surgery, the quality of life of post-COVID-19 infected persons seemed to be better.

Clinical trial registration

https://www.clinicaltrials.gov/, identifier: NCT04912778.

Combining Awake Anesthesia with Minimal Invasive Surgery Optimizes Intraoperative Surgical Spinal Cord Stimulation Lead Placement

Spinal cord stimulation (SCS) is an effective and validated treatment to address chronic refractory neuropathic pain in persistent spinal pain syndrome-type 2 (PSPS-T2) patients. Surgical SCS lead placement is traditionally performed under general anesthesia due to its invasiveness. In parallel, recent works have suggested that awake anesthesia (AA), consisting of target controlled intra-venous anesthesia (TCIVA), could be an interesting tool to optimize lead anatomical placement using patient intra-operative feedback. We hypothesized that combining AA with minimal invasive surgery (MIS) could improve SCS outcomes. The goal of this study was to evaluate SCS lead performance (defined by the area of pain adequately covered by paraesthesia generated via SCS), using an intraoperative objective quantitative mapping tool, and secondarily, to assess pain relief, functional improvement and change in quality of life with a composite score. We analyzed data from a prospective multicenter study (ESTIMET) to compare the outcomes of 115 patients implanted with MIS under AA (MISAA group) or general anesthesia (MISGA group), or by laminectomy under general anesthesia (LGA group). All in all, awake surgery appears to show significantly better performance than general anesthesia in terms of patient pain coverage (65% vs. 34-62%), pain surface (50-76% vs. 50-61%) and pain intensity (65% vs. 35-40%), as well as improved secondary outcomes (quality of life, functional disability and depression). One step further, our results suggest that MISAA combined with intra-operative hypnosis could potentialize patient intraoperative cooperation and could be proposed as a personalized package offered to PSPS-T2 patients eligible for SCS implantation in highly dedicated neuromodulation centers.

Goals, Expectations, and the Definition of Success for Neuromodulation for Pain According to Representatives of Neuromodulation Device Manufacturers

Representatives of neuromodulation device manufacturers are expected to facilitate the relationship between patients and healthcare providers. Nevertheless, the goals, expectations, and definition of success for neuromodulation for pain have not yet been explored. Representatives present at the 2nd Joint Congress of the INS European Chapters in September 2021 completed a survey to ascertain their opinions about the goals to achieve with neuromodulation, the factors that they expect to change, and their definition of success for neuromodulation. In total, 39 representatives completed the survey. To provide excellent service for patients (22.4%), to become a trusted partner for physicians (21.5%), and to provide excellent service for physicians (20.7%) were the highest ranked goals. The most frequently reported factors that were expected to change were pain intensity (23.1%), patient satisfaction (19.7%), mobility/functioning (14.5%), and capacity to return to work (13.7%). Within the definitions of success, increased quality of life of the patient was stated in 21% of the definitions, closely followed by pain control (19.3%) and happiness/patient satisfaction (15.8%). The goals of representatives of neuromodulation device manufacturers seem to focus on ensuring a good relationship with physicians on the one hand and providing good service towards patients on the other hand, whereby pain control, quality of life, and patient satisfaction seem to be important for company representatives.

Patient Selection for Spinal Cord Stimulation in Treatment of Pain: Sequential Decision-Making Model - A Narrative Review

Despite the well-known efficacy of spinal cord stimulation (SCS) in chronic pain management, patient selection in clinical practice remains challenging. The aim of this review is to provide an overview of the factors that can influence the process of patient selection for SCS treatment. A sequential decision-making model is presented within a tier system that operates in clinical practice. The first level incorporates the underlying disease as a primary indication for SCS, country-related reimbursement rules, and SCS screening-trial criteria in combination with underlying psychological factors as initial selection criteria in evaluating patient eligibility for SCS. The second tier is aligned with the individualized approach within precision pain medicine, whereby individual goals and expectations and the potential need for preoperative optimizations are emphasized. Additionally, this tier relies on results from prediction models to provide an estimate of the efficacy of SCS in the long term. In the third tier, selection bias, MRI compatibility, and ethical beliefs are included, together with recent technological innovations, superiority of specific stimulation paradigms, and new feedback systems that could indirectly influence the decision-making of the physician. Both patients and physicians should be aware of the different aspects that influence patient selection in relation to SCS for pain management to make an independent decision on whether or not to initiate a treatment trajectory with SCS.

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

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

A New Direction for Closed-Loop Spinal Cord Stimulation: Combining Contemporary Therapy Paradigms with Evoked Compound Action Potential Sensing

Spinal cord stimulation (SCS) utilizes the delivery of mild electrical pulses via epidural electrodes placed on the dorsal side of the spinal cord, typically to treat chronic pain. The first clinical use of SCS involved the delivery of paresthesia inducing, low-frequency waveforms to the neural targets corresponding to the painful areas. Contemporary SCS therapies now leverage novel therapeutic pathways to limit paresthesia and deliver superior clinical outcomes. Historically, SCS has largely been delivered with fixed stimulation parameters. This approach, referred to as open-loop (OL) SCS, does not account for the fluctuations in spacing-driven by postural changes and activity-between the electrodes and the cord. These fluctuations result in variability in the delivered dose and the volume of tissue activation (VTA) that manifests with each stimulation pulse. Inconsistent dosing may lead to suboptimal therapeutic efficacy and durability. To address this clinical need, closed-loop (CL) SCS systems have been developed to automatically adjust stimulation parameters to compensate for this variability. The evoked compound action potential (ECAP), a biopotential generated by the synchronous activation of dorsal column fibers, is indicative of the VTA resulting from the stimulation pulse. The ECAP may be utilized as a control signal in CL SCS systems to adjust stimulation parameters to reduce variability in the ECAP, and in turn, variability in the VTA. While investigational CL SCS systems with ECAP sensing have so far focused solely on managing paresthesia-based SCS, such systems must also incorporate the stimulation approaches that now define the contemporary clinical practice of SCS. Accordingly, we describe here a flexible, next-generation framework for neural responsive SCS that blends science-based methodologies for pain management with real-time CL control for biophysical variation. We conclude with a clinical example of such a system and the associated performance characteristics.

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

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

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

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

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.

A Novel Multi-Dimensional Clinical Response Index Dedicated to Improving Global Assessment of Pain in Patients with Persistent Spinal Pain Syndrome after Spinal Surgery, Based on a Real-Life Prospective Multicentric Study (PREDIBACK) and Machine Learning Techniques

The multidimensionality of chronic pain forces us to look beyond isolated assessment such as pain intensity, which does not consider multiple key parameters, particularly in post-operative Persistent Spinal Pain Syndrome (PSPS-T2) patients. Our ambition was to produce a novel Multi-dimensional Clinical Response Index (MCRI), including not only pain intensity but also functional capacity, anxiety-depression, quality of life and quantitative pain mapping, the objective being to achieve instantaneous assessment using machine learning techniques. Two hundred PSPS-T2 patients were enrolled in the real-life observational prospective PREDIBACK study with 12-month follow-up and received various treatments. From a multitude of questionnaires/scores, specific items were combined, as exploratory factor analyses helped to create a single composite MCRI; using pairwise correlations between measurements, it appeared to more accurately represent all pain dimensions than any previous classical score. It represented the best compromise among all existing indexes, showing the highest sensitivity/specificity related to Patient Global Impression of Change (PGIC). Novel composite indexes could help to refine pain assessment by informing the physician's perception of patient condition on the basis of objective and holistic metrics, and also by providing new insights regarding therapy efficacy/patient outcome assessments, before ultimately being adapted to other pathologies.

The Influence of Missing Data on Disabilities in Patients Treated with High-Dose Spinal Cord Stimulation: A Tipping Point Sensitivity Analysis

New waveforms have changed the field of Spinal Cord Stimulation (SCS) to optimize therapy outcomes, among which is High-Dose SCS (HD-SCS). Missing observations are often encountered when conducting clinical trials in this field. In this study, different approaches with varying assumptions were constructed to evaluate how conclusions may be influenced by these assumptions. The aim is to perform a tipping point sensitivity analysis to evaluate the influence of missing data on the overall conclusion regarding the effectiveness of HD-SCS on disability. Data from the Discover study were used, in which 185 patients with Failed Back Surgery Syndrome were included. Disability was evaluated before SCS and after 1, 3 and 12 months of HD-SCS. During the second, third and fourth visit, data from 130, 114 and 90 patients were available, respectively. HD-SCS resulted in a significant decrease in disability scores based on the analysis of observed data and with multiple imputations. The tipping point sensitivity analysis revealed that the shift parameter was 17. Thus, the conclusion concerning the time effect under a "missing at random" mechanism is robust when the shift parameter for the disability score is 17. From a clinical point of view, a shift of 17 points on disability is not very plausible. Therefore we tend to consider the conclusions drawn under "missing at random" as being robust.

Machine Learning Algorithms Provide Greater Prediction of Response to SCS Than Lead Screening Trial: A Predictive AI-Based Multicenter Study

Persistent pain after spinal surgery can be successfully addressed by spinal cord stimulation (SCS). International guidelines strongly recommend that a lead trial be performed before any permanent implantation. Recent clinical data highlight some major limitations of this approach. First, it appears that patient outco mes, with or without lead trial, are similar. In contrast, during trialing, infection rate drops drastically within time and can compromise the therapy. Using composite pain assessment experience and previous research, we hypothesized that machine learning models could be robust screening tools and reliable predictors of long-term SCS efficacy. We developed several algorithms including logistic regression, regularized logistic regression (RLR), naive Bayes classifier, artificial neural networks, random forest and gradient-boosted trees to test this hypothesis and to perform internal and external validations, the objective being to confront model predictions with lead trial results using a 1-year composite outcome from 103 patients. While almost all models have demonstrated superiority on lead trialing, the RLR model appears to represent the best compromise between complexity and interpretability in the prediction of SCS efficacy. These results underscore the need to use AI-based predictive medicine, as a synergistic mathematical approach, aimed at helping implanters to optimize their clinical choices on daily practice.

Finite Mixture Models Based on Pain Intensity, Functional Disability and Psychological Distress Composite Assessment Allow Identification of Two Distinct Classes of Persistent Spinal Pain Syndrome after Surgery Patients Related to Their Quality of Life

Persistent Spinal Pain Syndrome Type 2 (PSPS-T2), (Failed Back Surgery Syndrome), dramatically impacts on patient quality of life, as evidenced by Health-Related Quality of Life (HRQoL) assessment tools. However, the importance of functioning, pain perception and psychological status in HRQoL can substantially vary between subjects. Our goal was to extract patient profiles based on HRQoL dimensions in a sample of PSPS-T2 patients and to identify factors associated with these profiles. Two classes were clearly identified using a mixture of mixed effect models from a clinical data set of 200 patients enrolled in "PREDIBACK", a multicenter observational prospective study including PSPS-T2 patients with one-year follow-up. We observed that HRQoL was more impacted by functional disability for first class patients (n = 136), and by pain perception for second class patients (n = 62). Males that perceive their work as physical were more impacted by disability than pain intensity. Lower education level, lack of adaptive coping strategies and higher pain intensity were significantly associated with HRQoL being more impacted by pain perception. The identification of such classes allows for a better understanding of HRQoL dimensions and opens the gate towards optimized health-related quality of life evaluation and personalized pain management.

Pathogenesis, etiology and treatment of failed back surgery syndrome

Failed back surgery syndrome (FBSS) is associated with persistent lower back pain after and despite one or more surgical interventions. A number of factors underlie and maintain FBSS and successful management of pain chiefly depends on identifying them. Pharmacological, surgical, and non-surgical therapeutic measures are taken to treat the pain. Spinal cord stimulation and nerve stimulation have been widely practiced in this regard and enhanced pain reduction and patient satisfaction. In hernia and recurrent disc degeneration and sagittal imbalance, discectomy and/or fusion are indicated. The present review focuses on FBSS and its underlying components and on available treatment options.

A Call to Action Toward Optimizing the Electrical Dose Received by Neural Targets in Spinal Cord Stimulation Therapy for Neuropathic Pain

Spinal cord stimulation has seen unprecedented growth in new technology in the 50 years since the first subdural implant. As we continue to grow our understanding of spinal cord stimulation and relevant mechanisms of action, novel questions arise as to electrical dosing optimization. Programming adjustment — dose titration — is often a process of trial and error that can be time-consuming and frustrating for both patient and clinician. In this report, we review the current preclinical and clinical knowledge base in order to provide insights that may be helpful in developing more rational approaches to spinal cord stimulation dosing. We also provide key conclusions that may help in directing future research into electrical dosing, given the advent of newer waveforms outside traditional programming parameters.

Identifying goals in patients with chronic pain: A European survey

BACKGROUND

Chronic pain is a major healthcare issue that often requires an interdisciplinary treatment approach. Defining relevant treatment goals is one of the crucial steps in creating successful rehabilitation schemes. Therefore, the first aim was to explore goals that patients suffering from chronic pain aim to achieve. The second aim was to translate those goals into measurable functional outcome variables which can be used to measure treatment success.

METHODS

An online survey was developed and spread through local pain alliances in six European countries. Participants, patients suffering from chronic pain, were asked to report their most important goals, combined with a rank to denote the importance of each goal. For the highest ranked goals, participants were asked to decompose their goal into functional postures and the number of minutes per posture to achieve this goal.

RESULTS

We approached 1,494 persons, of which 487 effectively completed this survey. The highest ranked goals were taking part in family and social activities (72.55%), pain reduction (91.18%) and household tasks (68.14%). Obtaining pain reduction was most often ranked first (55.75%), followed by improving sleep (12.25%) and taking part in family or social activities (11.00%). For all goals, walking was a crucial component.

CONCLUSIONS

The goals of chronic pain patients are in line with previously explored expectations, denoting the importance of achieving pain relief combined with improvements on the level of activities and participation. This survey indicates that rehabilitation programs should definitely focus on improving walking ability, due to its importance in underpinning overall goal achievement.

SIGNIFICANCE

Goals and expectations of chronic pain patients are in line with each other. Obtaining pain relief remains the highest ranked goal, however, goals on the level of activities and participation were also highly ranked. Walking seems to be the overall crucial component for goal achievement.

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.

Predicting the Response of High Frequency Spinal Cord Stimulation in Patients with Failed Back Surgery Syndrome: A Retrospective Study with Machine Learning Techniques

Despite the proven clinical value of spinal cord stimulation (SCS) for patients with failed back surgery syndrome (FBSS), factors related to a successful SCS outcome are not yet clearly understood. This study aimed to predict responders for high frequency SCS at 10 kHz (HF-10). Data before implantation and the last available data was extracted for 119 FBSS patients treated with HF-10 SCS. Correlations, logistic regression, linear discriminant analysis, classification and regression trees, random forest, bagging, and boosting were applied. Based on feature selection, trial pain relief, predominant pain location, and the number of previous surgeries were relevant factors for predicting pain relief. To predict responders with 50% pain relief, 58.33% accuracy was obtained with boosting, random forest and bagging. For predicting responders with 30% pain relief, 70.83% accuracy was obtained using logistic regression, linear discriminant analysis, boosting, and classification trees. For predicting pain medication decrease, accuracies above 80% were obtained using logistic regression and linear discriminant analysis. Several machine learning techniques were able to predict responders to HF-10 SCS with an acceptable accuracy. However, none of the techniques revealed a high accuracy. The inconsistent results regarding predictive factors in literature, combined with acceptable accuracy of the currently obtained models, might suggest that routinely collected baseline parameters from clinical practice are not sufficient to consistently predict the SCS response with a high accuracy in the long-term.

Determining the Minimal Clinical Important Difference for Medication Quantification Scale III and Morphine Milligram Equivalents in Patients with Failed Back Surgery Syndrome

The Medication Quantification Scale III (MQS) is a tool to represent the negative impact of medication. A reduction in medication can serve as an indicator to evaluate treatment success. However, no cut-off value has yet been determined to evaluate whether a decrease in medication is clinically relevant. Therefore, the objective is to estimate the thresholds for the MQS and morphine milligram equivalents (MMEs) that best identify a clinically relevant important improvement for patients. Data from the Discover registry, in which patients with failed back surgery syndrome were treated with high-dose spinal cord stimulation, were used. Patient satisfaction was utilized to evaluate a clinically important outcome 12 months after stimulation. Anchor-based and distribution-based methods were applied to determine the minimal clinical important difference (MCID). Distribution-based methods revealed a value of 4.28 for the MQS and 33.61 for the MME as MCID. Anchor-based methods indicated a percentage change score of 41.2% for the MQS and 28.2% for the MME or an absolute change score of 4.72 for the MQS and 22.65 for the MME. For assessing a treatment outcome, we recommend using the percentage change score, which better reflects a clinically important outcome and is not severely influenced by high medication intake at baseline.