High-Density in Spinal Cord stimulation: Virtual Expert Registry (DISCOVER): Study Protocol for a Prospective Observational Trial

The Neurostimulation Appropriateness Consensus Committee (NACC)®: Recommendations for the Mitigation of Complications of Neurostimulation

INTRODUCTION

The International Neuromodulation Society convened a multispecialty group of physicians based on expertise and international representation to establish evidence-based guidance on the mitigation of neuromodulation complications. This Neurostimulation Appropriateness Consensus Committee (NACC)® project intends to update evidence-based guidance and offer expert opinion that will improve efficacy and safety.

MATERIALS AND METHODS

Authors were chosen on the basis of their clinical expertise, familiarity with the peer-reviewed literature, research productivity, and contributions to the neuromodulation literature. Section leaders supervised literature searches of MEDLINE, BioMed Central, Current Contents Connect, Embase, International Pharmaceutical Abstracts, Web of Science, Google Scholar, and PubMed from 2017 (when NACC last published guidelines) to October 2023. Identified studies were graded using the United States Preventive Services Task Force criteria for evidence and certainty of net benefit. Recommendations are based on the strength of evidence or consensus when evidence was scant.

RESULTS

The NACC examined the published literature and established evidence- and consensus-based recommendations to guide best practices. Additional guidance will occur as new evidence is developed in future iterations of this process.

CONCLUSIONS

The NACC recommends best practices regarding the mitigation of complications associated with neurostimulation to improve safety and efficacy. The evidence- and consensus-based recommendations should be used as a guide to assist decision-making when clinically appropriate.

Bioheat Model of Spinal Column Heating During High-Density Spinal Cord Stimulation

INTRODUCTION

High-density (HD) spinal cord stimulation (SCS) delivers higher charge per time by increasing frequency and/or pulse duration, thus increasing stimulation energy. Previously, through phantom studies and computational modeling, we demonstrated that stimulation energy drives spinal tissue heating during kHz SCS. In this study, we predicted temperature increases in the spinal cord by HD SCS, the first step in considering the potential impact of heating on clinical outcomes.

MATERIALS AND METHODS

We adapted a high-resolution computer-aided design-derived spinal cord model, both with and without a lead encapsulation layer, and applied bioheat transfer finite element method multiphysics to predict temperature increases during SCS. We simulated HD SCS using a commercial SCS lead (eight contacts) with clinically relevant intensities (voltage-controlled: 0.5-7 Vrms) and electrode configuration (proximal bipolar, distal bipolar, guarded tripolar [+-+], and guarded quadripolar [+--+]). Results were compared with the conventional and 10-kHz SCS (current-controlled).

RESULTS

HD SCS waveform energy (reflecting charge per second) governs joule heating in the spinal tissues, increasing temperature supralinearly with stimulation root mean square. Electrode configuration and tissue properties (an encapsulation layer) influence peak tissue temperature increase-but in a manner distinct for voltage-controlled (HD SCS) compared with current-controlled (conventional/10-kHz SCS) stimulation. Therefore, depending on conditions, HD SCS could produce heating greater than that of 10-kHz SCS. For example, with an encapsulation layer, using guarded tripolar configuration (500-Hz, 250-μs pulse width, 5-Vpeak HD SCS), the peak temperature increases were 0.36 °C at the spinal cord and 1.78 °C in the epidural space.

CONCLUSIONS

As a direct consequence of the higher charge, HD SCS increases tissue heating; voltage-controlled stimulation introduces special dependencies on electrode configuration and lead encapsulation (reflected in impedance). If validated with an in vivo measurement as a possible mechanism of action of SCS, bioheat models of HD SCS serve as tools for programming optimization.

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.

Rescue therapy with novel waveform spinal cord stimulation for patients with failed back surgery syndrome refractory to conventional stimulation: a systematic review and meta-analysis

OBJECTIVE

Conventional spinal cord stimulators (SCSs) have demonstrated efficacy in individuals with failed back surgery syndrome (FBSS). However, a subgroup of patients may become refractory to the effects of conventional waveforms over time. The objective of this study was to systematically review and evaluate the current literature on the use of novel waveform spinal cord stimulation for the management of FBSS refractory to conventional SCSs.

METHODS

A comprehensive electronic search of the literature published in electronic databases, including Ovid MEDLINE and Epub Ahead of Print, Ovid Cochrane Central Register of Controlled Trials, Ovid Cochrane Database of Systematic Reviews, and Scopus, was conducted using the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines. The outcomes of interest were reduction in back pain and/or leg pain after conversion from conventional to novel SCSs. Risk of bias was assessed with the Risk of Bias in Nonrandomized Studies of Interventions (ROBINS-I) tool. The strength of evidence was assessed using the Grading of Recommendations, Assessment, Development and Evaluations (GRADE) criteria.

RESULTS

A total of 6 studies with 137 patients with FBSS were identified. Studies were published between 2013 and 2021. The mean ± SD age of the pooled patient sample was 55 ± 10.5 years. All patients who underwent treatment with conventional SCSs were identified. Two studies evaluated the efficacy of high-density spinal cord stimulation, 3 studies evaluated burst spinal cord stimulation, and 1 study assessed multimodal waveforms. The mean difference in back pain scores after conversion from a standard SCS to a novel waveform SCS was 2.55 (95% CI 1.59-4.08), demonstrating a significant reduction in back pain after conversion to novel stimulation. The authors also performed a subgroup analysis to compare burst stimulation to tonic waveforms. In this analysis, the authors found no significant difference in the average reductions in back pain between the 2 groups (p = 0.534).The authors found an I2 statistic equivalent to 98.47% in the meta-regression model used to assess the effect of follow-up duration on study outcome; this value implied that the variability in the data can be attributed to the remaining between-study heterogeneity. The overall certainty was moderate, with a high risk of bias across studies.

CONCLUSIONS

Rescue therapy with novel waveform spinal cord stimulation is a potential option for pain reduction in patients who become refractory to conventional SCSs. Conversion to novel waveform SCSs may potentially mitigate expenses and complications.

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.

Research design considerations for randomized controlled trials of spinal cord stimulation for pain: Initiative on Methods, Measurement, and Pain Assessment in Clinical Trials/Institute of Neuromodulation/International Neuromodulation Society recommendations

ABSTRACT

Spinal cord stimulation (SCS) is an interventional nonpharmacologic treatment used for chronic pain and other indications. Methods for evaluating the safety and efficacy of SCS have evolved from uncontrolled and retrospective studies to prospective randomized controlled trials (RCTs). Although randomization overcomes certain types of bias, additional challenges to the validity of RCTs of SCS include blinding, choice of control groups, nonspecific effects of treatment variables (eg, paresthesia, device programming and recharging, psychological support, and rehabilitative techniques), and safety considerations. To address these challenges, 3 professional societies (Initiative on Methods, Measurement, and Pain Assessment in Clinical Trials, Institute of Neuromodulation, and International Neuromodulation Society) convened a meeting to develop consensus recommendations on the design, conduct, analysis, and interpretation of RCTs of SCS for chronic pain. This article summarizes the results of this meeting. Highlights of our recommendations include disclosing all funding source and potential conflicts; incorporating mechanistic objectives when possible; avoiding noninferiority designs without internal demonstration of assay sensitivity; achieving and documenting double-blinding whenever possible; documenting investigator and site experience; keeping all information provided to patients balanced with respect to expectation of benefit; disclosing all information provided to patients, including verbal scripts; using placebo/sham controls when possible; capturing a complete set of outcome assessments; accounting for ancillary pharmacologic and nonpharmacologic treatments in a clear manner; providing a complete description of intended and actual programming interactions; making a prospective ascertainment of SCS-specific safety outcomes; training patients and researchers on appropriate expectations, outcome assessments, and other key aspects of study performance; and providing transparent and complete reporting of results according to applicable reporting guidelines.

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.

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.

Efficacy of different spinal cord stimulation paradigms for the treatment of chronic neuropathic pain (PARS-trial): study protocol for a double-blinded, randomized, and placebo-controlled crossover trial

Background

Spinal cord stimulation (SCS) is an effective method to treat neuropathic pain; however, it is challenging to compare different stimulation modalities in an individual patient, and thus, it is largely unknown which of the many available SCS modalities is most effective. Specifically, electrodes leading out through the skin would have to be consecutively connected to different, incompatible SCS devices and be tested over a time period of several weeks or even months. The risk of wound infections for such a study would be unacceptably high and blinding of the trial difficult. The PARS-trial seizes the capacity of a new type of wireless SCS device, which enables a blinded and systematic intra-patient comparison of different SCS modalities over extended time periods and without increasing wound infection rates.

Methods

The PARS-trial is designed as a double-blinded, randomized, and placebo-controlled multi-center crossover study. It will compare the clinical effectiveness of the three most relevant SCS paradigms in individual patients. The trial will recruit 60 patients suffering from intractable neuropathic pain of the lower extremities, who have been considered for SCS therapy and were already implanted with a wireless SCS device prior to study participation. Over a time period of 35 days, patients will be treated consecutively with three different SCS paradigms (“burst,” “1 kHz,” and “1.499 kHz”) and placebo stimulation. Each SCS paradigm will be applied for 5 days with a washout period of 70 h between stimulation cycles. The primary endpoint of the study is the level of pain self-assessment on the visual analogue scale after 5 days of SCS.

Secondary, exploratory endpoints include self-assessment of pain quality (as determined by painDETECT questionnaire), quality of life (as determined by Quality of Life EQ-5D-5L questionnaire), anxiety perception (as determined by the Hospital Anxiety and Depression Scale), and physical restriction (as determined by the Oswestry Disability Index).

Discussion

Combining paresthesia-free SCS modalities with wireless SCS offers a unique opportunity for a blinded and systematic comparison of different SCS modalities in individual patients. This trial will advance our understanding of the clinical effectiveness of the most relevant SCS paradigms.

Trial registration

German Clinical Trials Register, DRKS00018929. Registered on 14 January 2020.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13063-020-05013-7.

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.

Management of Intractable Pain in Patients With Implanted Spinal Cord Stimulation Devices During the COVID-19 Pandemic Using a Remote and Wireless Programming System

As COVID-19 rampages throughout the world and has a major impact on the healthcare system, non-emergency medical procedures have nearly come to a halt due to appropriate resource reallocation. However, pain never stops, particularly for patients with chronic intractable pain and implanted spinal cord stimulation (SCS) devices. The isolation required to fight this pandemic makes it impossible for such patients to adjust the parameters or configuration of the device on site. Although telemedicine has shown a great effect in many healthcare scenarios, there have been fewer applications of such technology focusing on the interaction with implanted devices. Here, we introduce the first remote and wireless programming system that enables healthcare providers to perform video-based real-time programming and palliative medicine for pain patients with a SCS implant. During the COVID-19 pandemic from January 23, 2020, the date of lockdown of Wuhan, to April 30, 2020, 34 sessions of remote programming were conducted with 16 patients. Thirteen of the 16 patients required programming for parameter optimization. Improvement was achieved with programming adjustment in 12 of 13 (92.3%) cases. Eleven of the 16 (68.8%) patients reported that the system was user-friendly and met their needs. Five patients complained of an unstable connection resulting from the low network speed initially, and three of these patients solved this problem. In summary, we demonstrated that a remote wireless programming system can deliver safe and effective programming operations of implantable SCS device, thereby providing palliative care of value to the most vulnerable chronic pain patients during a pandemic.

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.

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

OBJECTIVE

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

METHODS

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

RESULTS

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

CONCLUSIONS

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

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.

The use of high-dose cervical spinal cord stimulation in the treatment of chronic upper extremity and neck pain

Background:

Dorsal column spinal cord stimulation is used for the treatment of chronic neuropathic pain of the axial spine and extremities. Recently, high-dose (HD) thoracic dorsal column stimulation for paresthesias has been successful. This study evaluates the utility of HD stimulation in the cervical spine for managing upper neck and upper extremity pain and paresthesias.

Methods:

Three patients suffering from cervical and upper extremity chronic pain were assessed. Each underwent a two-stage process that included a trial period, followed by permanent stimulator implantation. Therapy included the latest HD stimulation settings including a pulse width of 90 μs, a frequency setting of 1000 Hz, and an amplitude range of 1.5 amps–2.0 amps. Pain relief was measured utilizing relative percent pain improvement as self-reported by each patient before and after surgery.

Results:

After permanent implantation, (range 15–21 months), all three patients continued to experience persistent pain and paresthesia relief (70%–90%).

Conclusions:

In three patients, HD cervical spinal cord stimulation successfully controlled upper extremity chronic pain/paresthesias.

Cortical Mapping in Conventional and High Dose Spinal Cord Stimulation: An Exploratory Power Spectrum and Functional Connectivity Analysis With Electroencephalography

OBJECTIVES

Spinal cord stimulation (SCS) is considered an effective pain-relieving treatment for patients with Failed Back Surgery Syndrome (FBSS). Despite the clinical effectiveness, it is unknown whether the altered functional connectivity in such patients, as compared to healthy persons, can be influenced by SCS. Therefore, the goal of this study is to evaluate whether brain connectivity assessed by EEG differs between baseline and SCS in patients with FBSS.

MATERIALS AND METHODS

Eight patients with FBSS underwent a resting-state EEG protocol before SCS, 1.5 months and 2.5 months after receiving SCS. At each frequency band, power spectrums were compared for no SCS, conventional (CON) SCS and High Dose (HD) SCS. Functional connectivity, with the aid of eConnectome was also calculated.

RESULTS

Significant differences in the average power density spectrum over the whole scalp were observed between no SCS, CON SCS and HD SCS in delta, theta and beta frequency bands (p < 0.01). The average power spectrum for CON SCS was significantly lower than the average power spectrum for HD SCS. Marked increases in strength of the information flow between electrode pair FC3-TP9 in the beta frequency band (p = 0.006) were found in favor of HD SCS.

CONCLUSIONS

The differences in power spectrum and connectivity between the three conditions lead to the hypothesis that HD SCS differs from CON SCS on average power spectrum, suggesting that HD SCS may have a higher contribution on the excitatory bottom-up pathway.