Association of Spinal Cord Stimulator Implantation With Persistent Opioid Use in Patients With Postlaminectomy Syndrome.

Importance: The results of studies evaluating spinal cord stimulation (SCS) for postlaminectomy syndrome (PLS) have yielded mixed results. This has led to an increased emphasis on objective outcome measures such as opioid prescribing. Objective: To determine the association between SCS and long-term opioid therapy (LOT) for PLS. Design, Setting, and Participants: In this cohort study, adults with PLS were identified using the TriNetx Diamond Network and separated based on whether they underwent SCS. Patients were stratified according to baseline opioid use (opioid-naive or receiving LOT) and subsequent opioid therapy over the 12-month period ranging from 3 to 15 months post-SCS implantation or post-PLS index date. Statistical analysis was performed from June to December 2021. Exposure: SCS. Main Outcomes and Measures: The main outcome was cessation of opioid use among patients receiving LOT or abstinence from opioids among opioid-naive patients. Opioid-naive patients were defined as those receiving at most 2 opioid prescriptions per year, and patients on LOT were those receiving at least 6 opioid prescriptions per year. Results: Among 552 937 eligible patients treated between December 2015 and May 2021, 26 179 with PLS received an SCS implant. The median (IQR) patient age was 60 (51-69) years; 305 802 patients (55.3%) were female. Among those reporting racial identify (37.0% [204 758 patients]), 9.3% (18 971 patients) were African American, 0.3% (648 patients) were Asian, and 90.4% (185 139 patients) were White. Compared with those who did not receive an SCS, individuals who received an SCS were more likely to be using opioids preimplantation (mean [SD] prescriptions: 4.3 [8.5] vs 4.1 [9.3]; P < .001) but less likely to be using opioids after SCS implantation (mean [SD] prescriptions: 3.8 [8.2] vs 4.0 [9.4]; P = .006). In the 12-month study period, similar proportions in the SCS and no-SCS groups receiving baseline LOT remained on LOT (70.3% [n = 74 585] vs 69.2% [n = 3882], respectively; P = .10). In opioid-naive patients, SCS was associated with a small decreased likelihood of patients subsequently receiving LOT (7.6% vs 7.0%; difference, -0.6% [95% CI, -1.0% to -0.2%]; P = .003). In multivariable analysis, SCS was associated with an increased likelihood of not being on opioids in both opioid-naive (adjusted odds ratio [OR], 0.90 [95% CI, 0.85-0.96]; P < .001) and LOT patients (adjusted OR, 0.93 [95% CI, 0.88-0.99]; P = .02). White patients were significantly more likely to be diagnosed with PLS (ie, underwent surgery) (90.4% vs 85.2%; difference, 5.2% [95% CI, 5.1%-5.4%]; P < .001) and receive an SCS (93.7% vs 90.3%; difference, 3.4% [95% CI, 2.9% to 4.0%]; P < .001) than patients of other racial identities. Conclusions and Relevance: These findings suggest that under real-life conditions, SCS was associated with small, clinically questionable associations with opioid discontinuation and not starting opioids in the context of PLS.

Socioeconomic Disparities in the Utilization of Spinal Cord Stimulation Therapy in Patients with Chronic Pain.

OBJECTIVES: Spinal cord stimulation (SCS) therapies are used in the management of patients with complex regional pain syndrome I (CRPS I) and failed back surgery syndrome (FBSS). The purpose of this study was to investigate the racial and health insurance inequalities with SCS therapy in patients with chronic pain who had CRPS I and FBSS. METHODS: Patients with chronic pain who had a discharge diagnosis of FBSS and CRPS I were identified using the National Inpatient Sample database. Our primary outcome was defined as the history of SCS utilization by race/ethnicity, income quartile, and insurance status. Multivariable logistic regression was used to determine the variables associated with utilization of SCS therapy. RESULTS: Between 2011 and 2015, 40,858 patients who were hospitalized with a primary diagnosis of FBSS and/or CRPS I were identified. Of these patients, 1,082 (2.7%) had a history of SCS therapy. Multivariable regression analysis revealed that compared to White patients, Black and Hispanic patients had higher odds of having SCS therapy (Black patients: odds ratio [OR] = 1.41; 95% confidence interval [CI], 1.12 to 1.77; P = 0.003; Hispanic patients: OR = 1.41; 95% CI, 1.10 to 1.81; P = 0.007). Patients with private insurance had significantly higher odds of having SCS therapy compared with those with Medicare (OR = 1.24; 95% CI, 1.08 to 1.43; P = 0.003). Compared to patients with Medicare, Medicaid patients had lower odds of having SCS therapy (OR = 0.50; 95% CI, 0.36 to 0.70; P < 0.001). CONCLUSIONS: Our study suggests that socioeconomic disparities may exist in the utilization of SCS among hospitalized patients with CRPS I and FBSS the United States. However, confirming these data from other administrative databases, in the outpatient setting, may shed more insight.

Spinal cord stimulation and psychotropic medication use: Missing piece to the puzzle?

Psychotropic medications have modulatory effects on spinal cord stimulator (SCS) therapy and may play an important role in determining treatment success in chronic pain management. However, it remains unknown how SCS affects psychotropic use and whether the medications affect outcome. We performed a retrospective study to determine the prevalence of psychotropic medication (i.e. anxiolytic, antidepressant, and anticonvulsant) use among new SCS patients immediately before implantation and characterized the dosage changes at 1-year. We also sought to understand whether pre-operative medication status affects outcome, defined as device explantation due to treatment failure. In an analysis of 45 patients, 31%, 51% and 71% were actively taking anxiolytics, antidepressants, and anticonvulsants, respectively, before surgery. In the majority of cases, daily dosages remained the same for all three classes of medication at 1-year. Patients who were on two or more classes of medications pre-operatively had significantly lower explantation rate compared to those with one or none (12% vs. 43%, p = 0.041) and had 5.25 times less likelihood of explanation in the future (OR 5.25, 95%CI 1.18-23.2, p = 0.029). Our study suggest that peri-operative multimodality medical treatment may enhance the therapeutic efficacy and durability of SCS in carefully selected chronic pain patients.

Prevalence of smoking in adults with spinal cord stimulators: a systematic review and meta-analysis.

BACKGROUND: Smoking adversely impacts pain-related outcomes of spinal cord stimulation (SCS). However, the proportion of SCS patients at risk of worse outcomes is limited by an incomplete knowledge of smoking prevalence in this population. Thus, the primary aim of this systematic review is to determine the prevalence of smoking in adults with chronic pain treated with SCS. METHODS: A comprehensive search of databases from 1 January 1980 to 3 January 2019 was conducted. Eligible study designs included (1) randomized trials; (2) prospective and retrospective cohort studies; and (3) cross-sectional studies. The risk of bias was assessed using a tool specifically developed for prevalence studies. A total of 1619 records were screened, 19 studies met inclusion criteria, and the total number of participants was 10 838. RESULTS: Thirteen studies had low or moderate risk of bias, and six had a high risk of bias. All 19 studies reported smoking status and the pooled prevalence was 38% (95% CI 30% to 47%). The pooled prevalence in 6 studies of peripheral vascular diseases was 56% (95% CI 42% to 69%), the pooled prevalence of smoking in 11 studies of lumbar spine diagnoses was 28% (95% CI 20% to 36%) and the pooled prevalence in 2 studies of refractory angina was 44% (95% CI 31% to 58%). CONCLUSIONS: The estimated prevalence of smoking in SCS patients is 2.5 times greater than the general population. Future research should focus on development, testing and deployment of tailored smoking cessation treatments for SCS patients.

Neurophysiological markers predicting recovery of standing in humans with chronic motor complete spinal cord injury.

The appropriate selection of individual-specific spinal cord epidural stimulation (scES) parameters is crucial to re-enable independent standing with self-assistance for balance in individuals with chronic, motor complete spinal cord injury, which is a key achievement toward the recovery of functional mobility. To date, there are no available algorithms that contribute to the selection of scES parameters for facilitating standing in this population. Here, we introduce a novel framework for EMG data processing that implements spectral analysis by continuous wavelet transform and machine learning methods for characterizing epidural stimulation-promoted EMG activity resulting in independent standing. Analysis of standing data collected from eleven motor complete research participants revealed that independent standing was promoted by EMG activity characterized by lower median frequency, lower variability of median frequency, lower variability of activation pattern, lower variability of instantaneous maximum power, and higher total power. Additionally, the high classification accuracy of assisted and independent standing allowed the development of a prediction algorithm that can provide feedback on the effectiveness of muscle-specific activation for standing promoted by the tested scES parameters. This framework can support researchers and clinicians during the process of selection of epidural stimulation parameters for standing motor rehabilitation.

Increasing Rates of Imaging in Failed Back Surgery Syndrome Patients: Implications for Spinal Cord Stimulation.

BACKGROUND: Failed back surgery syndrome (FBSS) has a high incidence following spinal surgery, is notoriously refractory to treatment, and results in high health care utilization. Spinal cord stimulation (SCS) is a well-accepted modality for pain relief in this population; however, until recently magnetic resonance imaging (MRI) was prohibited due to risk of heat conduction through the device. OBJECTIVES: We examined trends in imaging use over the past decade in patients with FBSS to determine its impact on health care utilization and implications for patients receiving SCS. STUDY DESIGN: Retrospective. SETTING: Inpatient and outpatient sample. METHODS: We identified patients from 2000 to 2012 using the Truven MarketScan database. Annual imaging rates (episodes per 1000 patient months) were determined for MRI, computed tomography (CT) scan, x-ray, and ultrasound. A multivariate Poisson regression model was used to determine imaging trends over time, and to compare imaging in SCS and non-SCS populations. RESULTS: A total of 311,730 patients with FBSS were identified, of which 5.17% underwent SCS implantation (n = 16,118). The median (IQR) age was 58.0 (49.0 - 67.0) years. Significant increases in imaging rate ratios were found in all years for each of the modalities. Increases were seen in the use of CT scans (rate ratio [RR] = 3.03; 95% confidence interval [CI]: 2.79 - 3.29; P < 0.0001), MRI (RR = 1.73; 95% CI: 1.61 - 1.85; P < 0.0001), ultrasound (RR = 2.00; 95% CI: 1.84 - 2.18; P < 0.0001), and x-ray (RR = 1.10; 95% CI: 1.05 - 1.15; P < 0.0001). Despite rates of MRI in SCS patients being half that in the non-SCS group, these patients underwent 19% more imaging procedures overall (P < 0.0001). SCS patients had increased rates of x-ray (RR = 1.27; 95% CI: 1.25 - 1.29), CT scans (RR = 1.32; 95% CI: 1.30 - 1.35), and ultrasound (RR = 1.10; 95% CI: 1.07 - 1.13) (all P < 0.0001). LIMITATIONS: This study is limited by a lack of clinical and historical variables including the complexity of prior surgeries and pain symptomatology. Miscoding cannot be precluded, as this sample is taken from a large nationwide database. CONCLUSIONS: We found a significant trend for increased use of advanced imaging modalities between the years 2000 and 2012 in FBSS patients. Those patients treated with SCS were 50% less likely to receive an MRI (as expected, given prior incompatibility of neuromodulation devices), yet 32% and 27% more likely to receive CT and x-ray, respectively. Despite the decrease in the use of MRI in those patients treated with SCS, their overall imaging rate increased by 19% compared to patients without SCS. This underscores the utility of MR-conditional SCS systems. These findings demonstrate that imaging plays a significant role in driving health care expenditures. This is the largest analysis examining the role of imaging in the FBSS population and the impact of SCS procedures. Further studies are needed to assess the impact of MRI-conditional SCS systems on future trends in imaging in FBSS patients receiving neuromodulation therapies. Key words: Failed back surgery syndrome, spinal cord stimulation, imaging, health care utilization, MRI, chronic pain, back pain, neuromodulation.

Preferred frequencies and waveforms for spinal cord stimulation in patients with complex regional pain syndrome: A multicentre, double-blind, randomized and placebo-controlled crossover trial.

BACKGROUND: Conventional tonic spinal cord stimulation (SCS) is an effective treatment for patients with therapy-resistant complex regional pain syndrome (CRPS). Although the therapeutic effect of SCS can diminish over time due to tolerance, pain control can be regained by changing the pulse width and the amplitude and/or by increasing the stimulation frequency. This multicentre, double-blind, randomized and placebo-controlled crossover trial was conducted to investigate whether more effective pain reduction is achieved with different frequencies (trial registration, current controlled trials, ISRCTN 36655259). METHODS: The investigated settings are as follows: standard 40, 500, 1200 Hz, burst and placebo stimulation. All five were programmed in random order during the 10-week crossover period (2 weeks/setting). The primary outcome parameters were scores on the visual analogue scale (VAS), McGill Pain Questionnaire (MPQ) and the Global Perceived Effect (GPE); at the end of the crossover period, patients decided which SCS setting they preferred. A linear mixed models analysis was performed in 29 patients who completed the crossover trial. RESULTS: Significant pain reduction and GPE satisfaction was achieved with four SCS settings compared with placebo stimulation, and these four settings did not differ significantly from each other. Standard stimulation was preferred by 48% of the patients, while 52% preferred non-standard stimulation. Other than pain reduction, factors such as user-friendliness, comfort and recharging time may have influenced the patient's final decision for the preferred stimulation setting. CONCLUSIONS: Apparently, for various reasons, patients have a preference for different SCS setting. Therefore, future neuromodulation should aim to implement customized individual patient care by incorporating all stimulation options in one device. SIGNIFICANCE: This study demonstrates that standard frequency SCS is an effective therapy for patients with CRPS. However, it also demonstrates that patients can often gain better pain reduction with non-standard frequencies of SCS. Furthermore, it shows that the preferred stimulation setting is not solely driven by the amount of pain reduction, but is also influenced by which stimulation setting feels most comfortable and provides the best user-friendliness. Therefore, we strive to maximize the therapeutic effects of SCS in as many patients as possible. This can be achieved with customized individual patient care by incorporating the various frequencies and waveforms into one single device.

The Volume-Outcome Effect: Impact on Trial-to-Permanent Conversion Rates in Spinal Cord Stimulation.

OBJECTIVES: Conversion rates from trial leads to permanent spinal cord stimulation (SCS) systems have important implications for healthcare resource utilization (HCRU) and pain management. We hypothesized that there is a volume-outcome effect, with chronic pain patients who visit high volume SCS implanters will have higher trial-to-permanent conversion rates. MATERIALS AND METHODS: We designed a large, retrospective analysis using the Truven MarketScan database analyzing adult SCS patients with provider information available, with or without IPG implantation from the years 2007 to 2012 was designed. Patients were divided into three provider-based groups: high (>25), medium (9-24), and low (3-8) volume providers. Univariate and multivariate models identified factors associated with successful conversion. RESULTS: A total of 17,850 unique trial implants were performed by 3028 providers. Of 13,879 patients with baseline data available, 8981 (64.7%) progressed to permanent SCS. Higher volume providers were associated with slightly higher conversion rates (65.9% vs. 63.3% low volume, p = 0.029), explant rates (9.2% vs. 7.7% medium volume, p = 0.026), younger age (52.0 ± 13.4 years vs. 53.0 ± 13.4 years, p = 0.0026), Medicare/Medicaid (47.8% vs. 35.0% low volume, p < 0.0001), Southern region (53.5% vs. 38.9% low volume, p < 0.0001), and higher Charlson comorbidity scores (1.0 [SD = 1.4], p = 0.0002). Multivariate regression results showed female gender (1.13 [95% CI: 1.05-1.22], p < 0.001) and high volume providers associated with higher odds of successful trial conversion (1.12 [95% CI: 1.02-1.22], p = 0.014). CONCLUSIONS: In this nationwide analysis, high volume providers achieved higher trial-to-permanent SCS conversion rates than lower volume providers. The study has implications for both training requirements and referral patterns to delineate minimum implant experience necessary for provider proficiency. Future studies may be useful to understand HCRU differences.

A Comprehensive Outcome-Specific Review of the Use of Spinal Cord Stimulation for Complex Regional Pain Syndrome.

BACKGROUND: Complex regional pain syndrome (CRPS) is a painful, debilitating affliction that is often difficult to treat. It has become common international practice to use spinal cord stimulation (SCS) for the treatment of CRPS as other therapies fail to provide adequate relief, quality of life, or improvement in function. This comprehensive outcome-specific systematic review of the use of SCS for CRPS was performed to elucidate the available evidence with focus on clinically relevant patient-specific outcomes. METHODS: A systematic review of the literature was conducted to evaluate the effects of SCS on patients with CRPS for the following outcomes and provide summary levels of evidence in regard to each outcome: perceived pain relief, pain score, resolution of CRPS signs, functional status, quality of life, psychological impact, sleep hygiene, analgesic medication utilization, and patient satisfaction with SCS therapy. Search terms included "complex regional pain syndrome," "spinal cord stimulation," and "reflex sympathetic dystrophy," without restriction of language, date, or type of publication, albeit only original data were included in analyses. Of 30 studies selected, seven systematic reviews were excluded, as were four studies reporting combination therapy that included SCS and other therapies (ie, concurrent peripheral nerve stimulation, intrathecal therapy) without clear delineation to the effect of SCS alone on outcomes. A total of 19 manuscripts were evaluated. RESULTS: Perceived pain relief, pain score improvement, quality of life, and satisfaction with SCS were all rated 1B+, reflecting positive high-level (randomized controlled trial) evidence favoring SCS use for the treatment of CRPS. Evidence for functional status improvements and psychological effects of SCS was inconclusive, albeit emanating from a randomized controlled trial (evidence level 2B±), and outcomes evidence for both sleep hygiene and resolution of CRPS signs was either nonexistent or of too low quality from which to draw conclusions (evidence level 0). An analgesic sparing effect was observed in nonrandomized reports, reflecting an evidence level of 2C+. CONCLUSIONS: Spinal cord stimulation remains a favorable and effective modality for treating CRPS with high-level evidence (1B+) supporting its role in improving CRPS patients' perceived pain relief, pain score, and quality of life. A paucity of evidence for functional improvements, resolution of CRPS signs, sleep hygiene, psychological impact, and analgesic sparing effects mandate further investigation before conclusions can be drawn for these specific outcomes.

Is spinal cord stimulation safe? A review of 13 years of implantations and complications.

OBJECTIVE: The aim of this review was to evaluate the complications of spinal cord stimulation (SCS) for chronic pain. METHODS: This was a retrospective case series of 212 patients treated with SCS for chronic lower-limb neuropathic pain between March 2002 and February 2015 in a Reims academic hospital. All patients received a surgically implanted paddle-type electrode. Complications with this technique are here described and analyzed, and other treatment and preventative methods proposed. RESULTS: The major indication was 'failed back surgery syndrome', and 74 (35%) patients experienced complications, of which 57% were benign, while 42% required invasive treatment. Most frequent complications (n=22, 10%) were hardware malfunctions. There were two cases (0.9%) of postoperative neurological deficit and nine (4.2%) with postoperative infections. All patients received the appropriate treatment for their complication. CONCLUSION: Despite the presence of complications, SCS is still a safe technique, although careful patient selection and proper surgical technique can help to avoid major complications.

Longer Delay From Chronic Pain to Spinal Cord Stimulation Results in Higher Healthcare Resource Utilization.

INTRODUCTION: A shorter delay time from chronic pain diagnosis to spinal cord stimulation (SCS) implantation may make it more likely to achieve lasting therapeutic efficacy with SCS. The objective of this analysis was to determine the impact of pain-to-SCS time on patients' post-implant healthcare resource utilization (HCRU). METHODS: A retrospective observational study was performed using a real-world patient cohort derived from MarketScan(®) Commercial and Medicare Supplemental claims data bases from April 2008 through March 2013. The predictor variable was the time from the first diagnosis of chronic pain to permanent SCS implant. Using multivariable analysis, we studied the impact of pain-to-SCS time on HCRU in the first year post-implant. For some regression tests, patients were grouped into terciles by HCRU. RESULTS: A total of 762 patients met inclusion criteria, with a median pain-to-SCS time of 1.35 years (Q1: 0.8, Q3: 1.9). For every one-year increase in pain-to-SCS time, the odds increased by 33% for being in the high medical expenditures group (defined using the upper tercile: $4133 over above) over the low group (first lower: $603 or less). The odds increased by 39% for being in the high opioid prescriptions group (10-58 prescriptions) over the low group (0-1). The odds increased by 44% and 55%, respectively, for being in the high office visits (8-77) or hospitalizations (3-28) group over the low office visits (0-2) or hospitalizations (0) group. CONCLUSIONS: HCRU increased in the year following SCS implantation with longer pain-to-SCS time. These results suggest that considering SCS earlier in the care continuum for chronic pain may improve patient outcomes, with reductions in hospitalizations, clinic visits, and opioid usage.

Successful use of high-frequency spinal cord stimulation following traditional treatment failure.

INTRODUCTION: High-frequency spinal cord stimulation (HFSCS) offers an alternative treatment for chronic refractory pain syndromes nonresponsive to traditional spinal cord stimulation (SCS). Following the conflicting findings of preliminary HFSCS clinical studies performed at 5-10 kHz, this study is the first to report successful clinical usage of 1-kHz frequency SCS with a standard generator. PATIENTS: We used HFSCS in 2 patients who had inadequate relief with traditional SCS. Patient 1 was initially programmed at 40 Hz and a pulse width of 330 µs with bipolar stimulation. After multiple setting adjustments with inadequate pain relief, the patient was reprogrammed to HFSCS at settings of 1.15 kHz, 120 µs, and 5 V. Patient 2 was initially programmed at a frequency of 1.2 kHz and a pulse width of 120 µs, which she favored over the standard setting of 40 Hz and 390 µs pulse width. HFSCS provided optimal pain alleviation and increased quality of life for both patients. CONCLUSIONS: HFSCS at the frequency of 1 kHz offers a new tool for treatment of chronic pain in patients with traditional stimulation settings. Furthermore, most standard SCS batteries are capable of delivering stimulation in this frequency range.

The rate of magnetic resonance imaging in patients with spinal cord stimulation.

STUDY DESIGN: Analysis of use of magnetic resonance imaging (MRI) in the chronic back and leg pain spinal cord stimulation (SCS)-implanted population was conducted using a propensity-matched cohort population. OBJECTIVE: To project the percentage of patients with SCS expected to need at least 1 MRI within 5 years of implant. SUMMARY OF BACKGROUND DATA: Patients experiencing pain, including those who underwent implantation with SCS systems, are likely to have comorbidities and ongoing pain issues that may require diagnostic imaging. MRI is the most common diagnostic imaging modality for evaluating patients with new or worsening low back pain. However, patients with SCS are typically excluded from receiving MRI because of the safety risks related to the interactions of MRI fields and implantable devices. METHODS: To provide an accurate estimate of the need for MRI in the SCS-implanted population, Truven Health MarketScan Commercial Claims and Medicare Supplemental databases were used to perform analysis of SCS-implanted patients propensity score matched to a nonimplanted population-based cohort. Four years of paid and adjudicated claims data were used to determine the magnetic resonance (MR) images received, which was exponentially projected to estimate MRI within 5 and 10 years of implant. RESULTS: Approximately 82% to 84% of SCS-implanted patients are expected to need at least 1 MRI within 5 years of implant. Furthermore, 59% to 74% of patients will require nonspine MRI within 10 years. CONCLUSION: There is a high need for MRI in this chronic back and leg pain SCS population, with a significant portion being completed on locations outside of the spine. This analysis highlights a need for MRI-conditional SCS devices that grant access of patients with SCS to this imaging modality. LEVEL OF EVIDENCE: 3.

Present and potential use of spinal cord stimulation to control chronic pain.

BACKGROUND: Spinal cord stimulation is an intervention that has become increasingly popular due to the growing body of literature showing its effectiveness in treating pain and the reversible nature of the treatment with implant removal. It is currently approved by the FDA for chronic pain of the trunk and limbs, intractable low back pain, leg pain, and pain from failed back surgery syndrome. In Europe, it has additional approval for refractory angina pectoris and peripheral limb ischemia. OBJECTIVE: This narrative review presents the current evidence supporting the use of spinal cord stimulation for the approved indications and also discusses some emerging neuromodulation technologies that may potentially address pain conditions that traditional spinal cord stimulation has difficulty addressing. STUDY DESIGN: Narrative review. RESULTS: Spinal cord stimulation has been reported to be superior to conservative medical management and reoperation when dealing with pain from failed back surgery syndrome. It has also demonstrated clinical benefit in complex regional pain syndrome, critical limb ischemia, and refractory angina pectoris. Furthermore, several cost analysis studies have demonstrated that spinal cord stimulation is cost effective for these approved conditions. Despite the lack of a comprehensive mechanism, the technology and the complexity in which spinal cord stimulation is being utilized is growing. Newer devices are targeting axial low back pain and foot pain, areas that have been reported to be more difficult to treat with traditional spinal cord stimulation. Percutaneous hybrid paddle leads, peripheral nerve field stimulation, nerve root stimulation, dorsal root ganglion, and high frequency stimulation are actively being refined to address axial low back pain and foot pain. High frequency stimulation is unique in that it provides paresthesia free analgesia by stimulating beyond the physiologic frequency range. The preliminary results have been mixed and a large randomized control trial is underway to evaluate the future of this technology. Other emerging technologies, including dorsal root ganglion stimulation and hybrid leads, also show some promising preliminary results in non-randomized observational trials. LIMITATION: This review is a primer and not an exhaustive review for the current evidence supporting the use of spinal cord stimulation and precursory discussion of emerging neuromodulation technologies. This review does not address peripheral nerve stimulation and focuses mainly on spinal cord stimulation and touches on peripheral nerve field stimulation. CONCLUSIONS: Spinal cord stimulation has demonstrated clinical efficacy in randomized control trials for the approved indications. In addition, several open label observational studies on peripheral nerve field stimulation, hybrid leads, dorsal root ganglion stimulation, and high frequency stimulation show some promising results. However, large randomized control trials demonstrating clear clinical benefit are needed to gain evidence based support for their use.

Utilization of spinal cord stimulation in patients with failed back surgery syndrome.

STUDY DESIGN: Retrospective analysis of a population-based insurance claims data set. OBJECTIVE: To evaluate the use of spinal cord stimulation (SCS) and lumbar reoperation for the treatment of failed back surgery syndrome (FBSS), and examine their associated complications and health care costs. SUMMARY OF BACKGROUND DATA: FBSS is a major source of chronic neuropathic pain and affects up to 40% of patients who undergo lumbosacral spine surgery for back pain. Thus far, few economic analyses have been performed comparing the various treatments for FBSS, with these studies involving small sample sizes. In addition, the nationwide practices in the use of SCS for FBSS are unknown. METHODS: The MarketScan data set was used to analyze patients with FBSS who underwent SCS or spinal reoperation between 2000 and 2009. Propensity score methods were used to match patients who underwent SCS with those who underwent lumbar reoperation to examine health care resource utilization. Postoperative complications were analyzed with multivariate logistic regression. Health care use was analyzed using negative binomial and general linear models. RESULTS: The study cohort included 16,455 patients with FBSS, with 395 undergoing SCS implantation (2.4%). Complication rates at 90 days were significantly lower for SCS than spinal reoperation (P < 0.0001). Also in the matched cohort, hospital stay (P < 0.0001) and associated charges (P = 0.016) were lower for patients with SCS. However outpatient, emergency room, and medication charges were similar between the 2 groups. Overall cost totaling $82,586 at 2 years was slightly higher in the lumbar reoperation group than in the SCS group with total cost of $80,669 (P = 0.88). CONCLUSION: Although previous studies have demonstrated superior efficacy for the treatment of FBSS, SCS remains underused. Despite no significant decreases in overall health care cost with SCS implantation, because it is associated with decreased complications and improved outcomes, this technology warrants closer consideration for the management of chronic pain in patients with FBSS.

Impact of the National Institute for Health and Care Excellence (NICE) guidance on medical technology uptake: analysis of the uptake of spinal cord stimulation in England 2008-2012.

BACKGROUND: The National Institute for Health and Care Excellence (NICE) Technology Appraisal Guidance on spinal cord stimulation (SCS) was published in 2008 and updated in 2012 with no change. This guidance recommends SCS as a cost-effective treatment for patients with neuropathic pain. OBJECTIVE: To assess the impact of NICE guidance by comparing SCS uptake in England pre-NICE (2008-2009) and post-NICE (2009-2012) guidance. We also compared the English SCS uptake rate with that of Belgium, the Netherlands, France and Germany. DESIGN: SCS implant data for England was obtained from the Hospital Episode Statistics (HES) database and compared with other European countries where comparable data were available. RESULTS: The HES data showed small increases in SCS implantation and replacement/revision procedures, and a large increase in SCS trials between 2008 and 2012. The increase in the total number of SCS procedures per million of population in England is driven primarily by revision/replacements and increased trial activity. Marked variability in SCS uptake at both health regions and primary care trust level was observed. CONCLUSIONS: Despite the positive NICE recommendation for the routine use of SCS, we found no evidence of a significant impact on SCS uptake in England. Rates of SCS implantation in England are lower than many other European countries.

State of the field survey: spinal cord stimulator use by academic pain medicine practices.

OBJECTIVE: The concept of neuromodulation via the use of spinal cord stimulators (SCS) was first established over forty years ago. Since then, its popularity has grown as numerous studies have demonstrated its utility to reduce chronic pain, improve patient function, and reduce long-term health care costs. The aim of this study was to update the pain medicine community on the evolution of SCS practice trends in academic centers. DESIGN: Ninety-three pain medicine fellowship programs in the United States were identified from the Accreditation Council for Graduate Medical Education Website and were contacted to participate in an internet survey. A 37-item questionnaire was inspired by a previous study performed by Fanciullo et al. Questions focused on three main themes regarding SCS clinical application, namely demographics, education, and technical matters. RESULTS: Completed surveys were received from 50 institutions, all of which reported performing SCS interventions. Annual implants ranged from 0 to 150. Fellowship training was cited as the most valuable modality for learning implantation. Nearly all programs reported manufacturer representative participation during SCS procedures, with a minority of program directors discouraging their involvement in fellow education. SCS trials were performed exclusively on an outpatient basis. The average length for trials was 4-7 days. The most common indication for SCS implantation was failed back surgery syndrome, which also had the highest 2-year success rate. Post procedure, patients generally were followed up every 2-4 weeks for device reprogramming, which was performed by company representatives 92% of the time. CONCLUSION: Standardized SCS training is imperative as the implementation of neuromodulation therapy continues to increase.

Outcomes of percutaneous and paddle lead implantation for spinal cord stimulation: a comparative analysis of complications, reoperation rates, and health-care costs.

OBJECTIVES: Spinal cord stimulation (SCS) is a well-established modality for the treatment of chronic pain, and can utilize percutaneous or paddle leads. While percutaneous leads are less invasive, they have been shown to have higher lead migration rates. In this study, we compared the long-term outcomes and health-care costs associated with paddle and percutaneous lead implantation. MATERIALS AND METHODS: We utilized the MarketScan data base to examine patients who underwent percutaneous or paddle lead SCS system implantation from 2000 to 2009. Outcomes including complications, reoperation rates, and health-care costs were evaluated in propensity score matched cohorts using univariate and multivariate analyses. RESULTS: The study cohort was comprised of 13,774 patients. At 90 days following the initial procedure, patients in the SCS paddle group were more likely to develop a postoperative complication than patients receiving percutaneous systems (3.4% vs. 2.2%, p = 0.0005). Two-year (6.3% vs. 3.5%, p = 0.0056) and long-term (five+ years) (22.9% vs. 8.5%, p < 0.0008) reoperation rates were significantly higher in those with percutaneous lead systems. However, long-term health-care costs were similar for those receiving paddle and percutaneous leads ($169,768 vs. $186,139, p = 0.30). CONCLUSIONS: While the implantation of paddle leads is associated with slightly higher initial postoperative complications, these leads are associated with significantly lower long-term reoperation rates. Nonetheless, long-term health-care costs are similar between paddle and percutaneous leads. Additional improvements in SCS technologies that address the shortcomings of current systems are needed to reduce the risk of reoperation due to hardware failure. Further study is required to evaluate the efficacy of newer percutaneous and paddle SCS systems and examine their comparative outcomes.