Successful Spinal Cord Stimulation Research Articles

Impact of psychosocial factors on the success of neuromodulation treatment for patients with persistent pain

IntroductionSignificant interindividual variability in spinal cord stimulation (SCS) outcomes exists. Due to its high cost and risks of complications, criteria to guide patient selection for SCS trials and their outcomes...

Multiphase Spinal Cord Stimulation in Participants With Chronic Back or Leg Pain: Results of the BENEFIT-02 Randomized Clinical Trial

ObjectiveThis study aimed to assess the safety and effectiveness of a new charge-distributed multiphase stimulation paradigm during an extended spinal cord stimulation (SCS) trial. Materials and MethodsThis prospective, multicenter, randomized, single-blind, feasibility study included participants with chronic low back and/or leg pain and baseline numerical rating scale (NRS) for overall pain intensity ≥6. After a successful commercial SCS trial, participants were randomized to multiphase SCS therapy A (approximately 600–1500 Hz) or B (approximately 300–600 Hz), delivered via an investigational external pulse generator and existing leads during an 11-to-12–day testing period. Primary end points were mean NRS change from baseline to final in-office visit for each multiphase therapy and between therapies. Secondary end points included mean NRS change from end of commercial trial to final study visit and incidence of device-related adverse events (AEs). Additional measures included patient-reported outcomes collected at home through electronic watches and written diaries. Power usage was compared between multiphase and commercial therapies. ResultsA total of 122 participants initiated a commercial trial; 77 were randomized to a multiphase arm, and 65 completed the study. Reductions in mean NRS scores from baseline to final study visit were significant for multiphase therapy A and B (−4.3 and −4.7, respectively; both p < 0.0001). There was no statistically significant difference in mean NRS reduction or percent pain relief between multiphase therapies. In an additional analysis, 63.9% of participants reported greater pain relief with multiphase than with commercial SCS therapy in the at-home setting. On average, multiphase required less power than did commercial devices. One non–serious device-related AE was reported, and no infections occurred during the extended trial. ConclusionsMultiphase SCS effectively reduced pain in participants with chronic low back and/or leg pain during a trial, with no unanticipated device-related AEs reported. Future studies should evaluate long-term effectiveness of multiphase stimulation. Clinical Trial RegistrationThe Clinicaltrials.gov registration number for the study is NCT03594266.

ID: 216326 Improvement in Chronic Pain Induced Depression With Spinal Cord Stimulation Therapy

A detailed psychological evaluation is an important tool utilized by physicians to help predict the success of spinal cord stimulation (SCS) therapy. Psychological factors such as anxiety, depression and mood disorders may play a large predictive component in SCS failure. The high coexistence between depression and chronic pain, however, can complicate the picture. Recent studies have substantiated this complexity, and have started to place more value on the psychosocial and behavioral factors such as coping mechanisms, and social support. Herein, the authors present an interesting case of a 47 year old female with a significant psychiatric history that had significant improvement in her mood and overall mental health after SCS implant.

ID: 207977 Impact of Insurance on the Success of Spinal Cord Stimulation

Spinal cord stimulation (SCS) is used to treatment various chronic pain conditions. Studies have shown racial and socioeconomic disparities in numerous aspects of healthcare, including SCS. Due to the financial ramifications, it is not uncommon in the US for SCS to be not offered to the Medicaid population. Despite the potential for financial concerns, some systems offer SCS to all patients regardless of insurance. We evaluated the success rate of SCS trial based on insurance for potential impact of insurance of the success of SCS.

Machine Learning in Spinal Cord Stimulation for Chronic Pain.

Spinal cord stimulation (SCS) is an effective treatment for chronic neuropathic pain. The success of SCS is dependent on candidate selection, response to trialing, and programming optimization. Owing to the subjective nature of these variables, machine learning (ML) offers a powerful tool to augment these processes. Here we explore what work has been done using data analytics and applications of ML in SCS. In addition, we discuss aspects of SCS which have narrowly been influenced by ML and propose the need for further exploration. ML has demonstrated a potential to complement SCS to an extent ranging from assistance with candidate selection to replacing invasive and costly aspects of the surgery. The clinical application of ML in SCS shows promise for improving patient outcomes, reducing costs of treatment, limiting invasiveness, and resulting in a better quality of life for the patient.

The Choice of Spinal Cord Stimulation Versus Targeted Drug Delivery in the Management of Chronic Pain: Validation of an Outcomes Predictive Formula

ObjectiveIn 2020, Mekhail et al published a formula that predicted the likelihood of a successful outcome for those who undergo spinal cord stimulation (SCS) for long-term pain management, based on retrospectively collected clinical and demographic data from one major medical center. The aim of this study is to validate such a predictive formula, prospectively, in a cohort of patients from multiple medical practices that are more representative of real-life clinical practice. Materials and MethodsFor the study, 939 patients who underwent successful SCS or targeted drug delivery (TDD) trials at multiple independent medical centers in the USA were enrolled into the Medtronic product surveillance registry data base before they underwent SCS or TDD device implantation, from 2018 to 2020. The registry data were collected prospectively but not specifically for this study. The data examined included demographic information, pain diagnosis, pain scores (visual analog scale [VAS]), Oswestry Disability Index scores, and quality-of-life scores at baseline and six months after implant. Because our goal is to validate the previously published predictive formula, in addition to the outcomes data previously mentioned, we collected the variables necessary for such a task: sex, age, depression, the presence of neuropathic pain, spine-related pain diagnosis, and persistent spinal pain syndrome “post laminectomy syndrome.” Spine-related pain diagnosis included subjects with chronic spine pain who never had back surgery and whose pain was not radicular nor neuropathic. ResultsOf 619 patients with SCS, 138 (22%) achieved ≥ 50% reductions of the baseline VAS at six months. The logistic model predicts SCS success with an area under the receiver operating characteristic curve (AUC) of 80% in the current validation data set. Of 320 patients with TDD, 147 (46%) achieved ≥ 50% reduction of the baseline VAS at six months. The logistic model predicts TDD success with an AUC of 78% in the current validation data set. ConclusionThe study provides real life validation of the previously published predictive formula(4).

Use of Accelerometry as an Educational Tool for Spinal Cord Stimulation: A Pilot Study.

Spinal cord stimulation (SCS) is an important option for patients with chronic neuropathic pain. In the United States, a successful SCS trial determines eligibility for SCS implant. Metrics to determine success are often self-reported and subjective, which may limit achievement of patient goals. This study aimed to assess whether patients undergoing SCS implant after successful trial felt that use of external accelerometry prior to implant was a useful educational tool to objectively appraise function and achievement of treatment goals. This was a single center, prospective, pilot study. Sixteen subjects with persistent spinal pain syndrome type 2 underwent a percutaneous SCS trial. Five subjects did not have a successful trial, one expired after the SCS trial, before implant, and one dropped out prior to completion of post-implant follow-up visits. Nine subjects underwent SCS implant and completed the required follow-up visits. All subjects were provided an Actigraph GT3X external accelerometer, worn 7 days prior to the trial to determine baseline physical activity and during the 7-day trial to assess for change in activity from baseline. Results were shared with subjects to individualize goals for therapy. Goal attainment was assessed at 1, 3, and 6 months after implant. Subjects wore the accelerometer again 24 hours before visits to update progress in meeting treatment goals. The primary outcome was satisfaction with using accelerometry as an educational tool to appraise function and guide treatment goals for SCS therapy. Secondary outcomes included physical activity, as captured via accelerometry, as well as validated patient-reported measures of pain severity, physical functioning, and quality-of-life. Eight of nine subjects were satisfied with accelerometry as an educational tool. Secondary outcomes were not reliably assessed due to poor stewardship and study execution. External accelerometry may assist patients in developing individualized functional treatment goals for SCS therapy.

Factors associated with success of trial spinal cord stimulation in patients with chronic pain

Objective: Spinal cord stimulation (SCS) is a widely employed technique in treating chronic pain, however, it still fails in significantly reducing pain in one-out-of-three cases. Poor consensus exists on the most predictive factors of SCS outcomes. Although psychological criteria such as emotional stability are recommended for this treatment, it is not well understood if the perception of patients’ own health may impact the SCS success. Therefore, we retrospectively examine factors associated with the patient's subjective conditions, to investigate their relationship with SCS success. Methods: Before the implantation of an SCS trial per routine clinical decision-making, and independently from the implanted devices, patients treated in our clinical practice underwent an extensive evaluation of pain, disability, depression and the overall quality of life. In those patients with successful SCS trials, the pain level was also evaluated at the end of the trial period. Regression analyses were performed to investigate factors predicting successful trial stimulation. Results: Successful trial stimulation was effective in 15 patients (75%). Perceived disability, pain and general health resulted as independent predictive factors on SCS trial outcome. Further investigation showed perceived disability (i.e. Oswestry Disability Index) as a crucial factor, and ROC curve analysis identifies a cut-off of 38 as a predictive score of success. Conclusions: Although preliminary, these findings suggest that standardized scales examining the overall patients’ perceived health status, particularly the disability index may help shed light on predicting SCS trial success. Thus, it is argued the potential application of self-administered scales in SCS patients’ selection in routine clinical practice.

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

IntroductionNowadays, 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 MethodsBaseline 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. ResultsModel-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. ConclusionsClustering 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 RegistrationThe Clinicaltrials.gov registration number for the Discover study is NCT02787265.

Comparison of Spinal Cord Stimulation Trial Reporting Protocols and Long-Term Pain Relief Outcomes Following Implantation

ObjectivesAppropriate spinal cord stimulation (SCS) candidates are required to undergo an SCS trial before implant, typically with ≥50% pain relief deemed “successful.” However, SCS trialing protocols can vary substantially. The primary aim of this retrospective study is to investigate the associations between SCS trial results and long-term SCS pain outcomes. Materials and MethodsThis study was a retrospective single-center review of successful SCS trials from January 1, 2017, to July 1, 2019. A total of 115 patients were included. Group differences in continuous variables were evaluated using t-tests, and group differences in categorical variables were evaluated using the χ2 test. The percentage improvement in long-term pain intensity was analyzed as a binary variable, where long-term success was defined as ≥50% improvement in numeric rating scale pain scores. The level of significance for all tests was set at p < 0.05. ResultsThe mean age was 64.9 years, and 52% of patients were men. The mean pain score at long-term follow-up was 4.7 ± 2.6, and the median time from implantation to follow-up was 13 months (25th–75th interquartile range; 4–22). In the logistic regression analysis adjusted for age, sex, and follow-up time, greater patient-reported percentage improvement in pain scale during the trial was significantly associated with greater odds of experiencing ≥50% improvement in pain scores (p = 0.048; 95% CI 1.00–1.70). All other assessed trial metrics were not significantly associated with greater odds of experiencing >50% improvement in pain scores at last follow-up. ConclusionsGiven the variability in current assessment techniques, we recommend the patient-reported percentage improvement in pain scale as the posttrial assessment method of choice instead of a calculated percentage improvement. However, our results indicate that current trial assessment methods are generally poor, and improved trial reporting protocols must be sought.

Association of Outcomes of Spinal Cord Stimulation for Chronic Low Back Pain and Psoas Measurements Based on Size of Iliopsoas Muscles

IntroductionPatients experience variable long-term improvement in chronic back pain despite successful spinal cord stimulation (SCS) trials. Iliopsoas (IP) size has been shown to differ between patients with low back pain and healthy controls. In this study, we examine whether the IP muscle cross-sectional area (CSA) is associated with SCS outcomes. Materials and MethodsWe examined patients for whom we had lumbar MRIs 6.3 years prior to SCS and baseline and one-year outcome data. Percent change from baseline to one year was calculated for Numeric Rating Scale (NRS), Oswestry Disability Index (ODI), Beck Depression Inventory (BDI), Pain Catastrophizing Scale (PCS), and McGill Pain Questionnaire (MPQ). Correlations between IP muscle CSA, ratio of iliopsoas muscle size to the vertebral body area (P/VBA), and the ratio of iliopsoas muscle size to BMI (P/BMI) were examined. Sex differences were considered. ResultsA total of 73 subjects were included in this study, including 30 females and 43 males. Males had significantly larger IP (males 15.70 ± 0.58, females 9.72 ± 0.43; p < 0.001), P/VBA (males 1.00 ± 0.04, females 0.76 ± 0.03; p < 0.001), and P/BMI ratio (males 0.51 ± 0.02, females 0.32 ± 0.01; p < 0.001) than females. In females, P/VBA predicted NRS worst pain scores (β = 0.82, p = 0.004, r2 = 0.55) and BDI (β = 0.59, p = 0.02, r2 = 0.24). In males, P/BMI was a significant predictor of BDI outcome scores (β = 0.45, p = 0.03, r2 = 0.16). Males who had more muscle mass measured by iliopsoas size had more depression as measured using BDI (p = 0.03, r = 0.61). Females with less muscle mass measured by P/VBA also experienced more depression (p = 0.02, r = 0.74). ConclusionsOur study showed that psoas measurements correlated with various pain outcomes specifically. P/VBA was most predictive in females and P/BMI in males. Depression correlated with P/BMI, reinforcing the complex relationship between depression and constant chronic pain. Tertile analyses further showed a relationship between iliopsoas CSA and depression in males and females. We provide preliminary data of sex-specific psoas measurements as a risk factor for worse SCS outcomes.

Spinal Cord Stimulation of the Sacral Region as a Treatment for Intractable Coccygodynia: A Case Study

BACKGROUND: Coccygodynia is a notoriously difficult condition to manage. Spinal cord stimulation (SCS) may be a promising therapeutic option for those suffering from chronic coccygeal pain. To our knowledge, there are limited reports of using SCS to target the sacral region for the treatment of intractable coccygodynia. CASE REPORT: A 50-year-old woman with refractory coccygodynia underwent permanent implantation of an SCS device following a successful SCS trial. SCS leads were inserted using a retrograde approach to target S2-S4 bilaterally. During follow-up, the patient reported &gt; 90% improvement of coccygeal pain and her selfreported quality of life dramatically improved. CONCLUSION: This case report describes the successful use of the sacral region as a target for SCS in the management of intractable coccygodynia. SCS may be considered an effective treatment option when all other conventional methods have failed. KEY WORDS: Coccygodynia, neuromodulation, sacral nerve stimulation, spinal cord stimulation

Spinal Cord Stimulator Trial in a Patient on Chronic Warfarin Therapy

Background: Spinal cord stimulation (SCS) is a rapidly growing interventional treatment modality in chronic pain. Pain physicians are faced with the decision on how to manage patients on anticoagulation therapy given the risk of epidural hematomas. Case Report: We describe a patient with a history of atrial fibrillation and prior pulmonary embolism on chronic anticoagulation. The patient was planned to undergo an SCS trial, but was unable to discontinue all anticoagulation during the length of the trial. Utilizing a multidisciplinary approach, the patient discontinued warfarin 5 days prior to the procedure and began a therapeutic dose of low molecular weight heparin (LMWH). The final dose of LMWH was given 24 hours before the trial procedure. The patient then started prophylactic dosing of LMWH 24 hours after the trial procedure and continued that regimen for the course of the SCS trial. The last dose of prophylactic LMWH was given 24 hours before removal of the trial leads and the patient restarted 3 days of therapeutic LMWH along with resuming his normal anticoagulation regimen after lead removal. The patient was able to undergo a successful SCS trial and will be pursuing a SCS implant with further anticoagulation management. Conclusion: This case demonstrates a possible strategy for managing patients who requiring anticoagulation therapy during the course of their SCS trial phase. Although a single-electrode array proved to be efficacious, using 2 electrode arrays improves the anatomic coverage of the painful areas and allows for greater optionality in electrode selections to avoid plasticity. Key words: Spinal cord stimulation, anticoagulation, chronic pain, post laminectomy syndrome

Deep Learning Versus Logistic Regression to Predict Opioid Dose Reduction After Spinal Cord Stimulation

Abstract INTRODUCTION Opioid misuse persists as a public health crisis affecting approximately one in four Americans.1 Spinal cord stimulation (SCS) is a neuromodulation strategy to treat chronic pain, with one goal being decreased opioid consumption. Accurate prognostication about SCS success is key in optimizing surgical decision making for both physicians and patients. Deep learning, using neural network models such as the multilayer perceptron (MLP), enables accurate prediction of non-linear patterns and has widespread applications in healthcare. METHODS The IBM MarketScan® (IBM) database was queried for all patients ≥ 18 years old undergoing SCS from January 2010 to December 2015. Patients were categorized into opioid dose groups as follows: No Use, ≤ 20 morphine milligram equivalents (MME), 20–50 MME, 50–90 MME, and &amp;gt;90 MME. We defined “opiate weaning” as moving into a lower opioid dose group (or remaining in the No Use group) during the 12 months following permanent SCS implantation. After pre-processing, there were 62 predictors spanning demographics, comorbidities, and pain medication history. We compared an MLP with four hidden layers to the LR model with L1 regularization. Model performance was assessed using area under the receiver operating characteristic curve (AUC) with 5-fold nested cross-validation. RESULTS Ultimately, 6,124 patients were included, of which 77% had used opioids for &amp;gt;90 days within the 1-year pre-SCS and 72% had used &amp;gt;5 types of medications during the 90 days prior to SCS. The mean age was 56 ± 13 years old. Collectively, 2,037 (33%) patients experienced opiate weaning. The AUC was 0.74 for the MLP and 0.73 for the LR model. CONCLUSION To our knowledge, we present the first use of deep learning to predict opioid weaning after SCS. Model performance was slightly better than regularized LR. Future efforts should focus on optimization of neural network architecture and hyperparameters to further improve model performance. Models should also be calibrated and externally validated on an independent dataset. Ultimately, such tools may assist both physicians and patients in predicting opioid dose reduction after SCS.

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.

Spinal Cord Stimulation for Chronic Pain Syndromes: A Review of Considerations in Practice Management

Background Chronic pain syndromes are clinically challenging to treat, and management with opioid medications is increasingly shown to be inappropriate and ineffective. Spinal cord stimulation (SCS) has been demonstrated across numerous high-quality and well-designed studies to be effective in treating various refractory chronic pain. The efficacy and overall success of SCS is highly dependent on compliance to and consideration of various practice patterns. Objective This manuscript is intended to compile and present comprehensive recommendations for key SCS management principles including: a) patient selection criteria, b) efficacy of SCS for various conditions, c) discussion of SCS waveforms, d) trial and permanent implantation considerations, e) periprocedural management, and f) complications and adverse events. Study design An evidence-based narrative review. Methods PubMed, Medline, Cochrane Library, prior systematic reviews, and reference lists were screened by 2 separate authors for all randomized trials, meta-analyses, and observational studies relevant to each of the aforementioned management principles and considered for study inclusion. Results All high-level evidence studies that explored the various facets of SCS practice management were included for review. Limitations Both continued investigation into, and practice implementation of, the various facets of SCS management are necessary to optimize patient outcomes. Conclusion Implementation of and adherence to the evidenced-based recommendations delineated in this publication may help optimize efficacy outcomes and maintain safety profiles for persons treated with SCS interventions.

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.

Association Between Pain Scores and Successful Spinal Cord Stimulator Implantation

Determining reduction in pain score during spinal cord stimulation (SCS) trial is important prior to permanent SCS implantation. However, this association remains elusive. We investigate the association between post-SCS pain scores and successful permanent SCS implants. This IRB-approved, retrospective study identified patients who underwent SCS trials and implantation. Predictive modeling with nonparametric regression and margins plot analysis was used to determine the threshold for post-SCS trial pain scores associated with successful permanent SCS implant (defined as >50% pain relief). Nonparametric sensitivity and specificity analysis was performed. p < 0.05 was considered significant. Eighty-eight patients with SCS trials were retrospectively identified (57.95% female, median age 52.5 ± 15.5 years). Of the total cohort, 79% had successful permanent SCS implantation. Post-SCS trial pain scores less than or equal to 4.9 had greater than 50% probability of a successful permanent SCS implant (97.14% sensitivity, 44.44% specificity, ROC = 0.71). Post-SCS trial pain scores between 4 and 7 were associated with a significantly higher probability of a successful SCS implant among patients without spine surgery compared with those with a history of spine surgery. Compared with males, females with pain scores between 5 and 7 had a higher probability of a successful SCS implant. Low pain scores after SCS trial are predictive of successful SCS implants with high sensitivity. Males and surgical patients with higher pain scores had a lower probability of successful SCS implant than their counterparts. Larger studies are needed to further elucidate this relationship.

10kHz spinal cord stimulation for chronic upper limb and neck pain: Australian experience.

Intractable upper limb and neck pain has traditionally been a challenging pain condition to treat, with conventional spinal cord stimulation (SCS) often inducing positional variation in paraesthesia and/or inadequate coverage of axial neck pain. The purpose of this Australian multi-centre prospective, clinical trial was to assess the safety and effectiveness of paraesthesia-independent 10kHz SCS for the treatment of upper limb and neck pain. Subjects with chronic, intractable neck and/or upper limb pain of ≥ 5cm (on a 0-10-cm visual analogue scale) were enrolled (ACTRN12614000153617) following human research ethics committee approval. Subjects were implanted with two epidural leads spanning C2-C6 vertebral bodies. Subjects with successful trial stimulation were implanted with a Senza® system (Nevro Corp., Redwood City, CA, USA) and included in the safety and effectiveness evaluation at 3 months post-implant (primary endpoint assessment, PEA) and followed to 12 months. Overall, 31/38 (82.6%) subjects reported a successful 10kHz SCS trial and proceeded to a permanent implant. Twenty-three of 30 subjects (76.7%) met the PEA. Subjects reported a reduction in neck pain and upper limb pain from baseline at the PEA (8.1 ± 0.2cm vs. 2.9 ± 0.5cm, 7.3 ± 0.3cm vs. 2.5 ± 0.5cm, respectively, p ≤ 0.0001). Disability, as measured by pain disability index score, decreased from 42.6 ± 2.6 at baseline to 22.7 ± 3.2 at PEA. Results were maintained 12 months post-implant. No neurological deficits, nor reports of paraesthesia, were observed. Stable, long-term results demonstrated that 10kHz SCS is a promising therapy option for intractable chronic upper limb and neck pain.

Unsuccessful Spinal Cord Stimulator Re-trial from Failure to Capture in a Patient with Prior Successful Trial but Failed Implant Attempt Due to Lack of Paresthesia

Background: Spinal cord stimulation (SCS) is a widely accepted pain treatment modality for failed-back surgery, peripheral vascular disease-causing claudication pain, and complex regional pain syndrome. However, despite a rigorous patient selection, not all patients deemed as good candidates result in a successful trial, reasons often unknown. Herein, we present a case of unsuccessful SCS re-trial due to complete failure to capture in a patient with a prior successful trial, but failed implant attempt. Case Report: Patient is a 78 year-old male with multiple myeloma who was followed in the chronic pain clinic for chronic pain syndrome, cancer pain syndrome and peripheral neuropathy. Patient’s main pain complaints are left leg pain, lower back pain likely neuropathic, nociceptive pain from the underlying metastatic lytic lesions, as well as peripheral neuropathy. Medications include gabapentin, hydromorphone, and fentanyl patch. Previously, patient underwent a successful SCS trial by his local pain physician followed by an attempt at permanent implant, which was aborted due to failure to perceive paresthesia. Recently, we proceeded with the SCS trial. The procedure itself was rather unremarkable, with both leads walked up to the mid-vertebral body of T8. However, there was failure to capture; the leads were pulled down separately to T12 with patient having no sensory response at high amplitudes at each level between T8 to T12. The trial leads were subsequently pulled out. Conclusion: This complete failure to capture has never been reported and it could partially be explained due to extensive scarring/fibrosis from the prior SCS trial and implant attempt. Key words: Spinal cord stimulator, failure to capture, central pain