Spinal Cord Stimulation With Additional Peripheral Nerve/Field Stimulation Versus Spinal Cord Stimulation Alone on Back Pain and Quality of Life in Patients With Persistent Spinal Pain Syndrome

IntroductionPersistent spinal pain syndrome (PSPS) or failed back surgery syndrome (FBSS) refers to new or persistent pain following spinal surgery for back or leg pain in a subset of patients. Spinal cord stimulation (SCS) is a neuromodulation technique that can be considered in patients with predominant leg pain refractory to conservative treatment. Patients with predominant low back pain benefit less from SCS. Another neuromodulation technique for treatment of chronic low back pain is subcutaneous stimulation or peripheral nerve field stimulation (PNFS). We investigated the effect of SCS with additional PNFS on pain and quality of life of patients with PSPS compared with that of SCS alone after 12 months.Materials and MethodsThis is a comparative study of patients with PSPS who responded to treatment with either SCS + PNFS or SCS only following a multicenter randomized clinical trial protocol. In total, 75 patients completed the 12-month follow-up: 21 in the SCS-only group and 54 in the SCS + PNFS group. Outcome measures were pain (visual analog scale), quality of life (36-Item Short Form Survey [SF-36]), anxiety and depression (Hospital Anxiety and Depression Scale [HADS]), overall health (EuroQol Five-Dimension [EQ-5D]), disability (Oswestry Disability Index [ODI]), and pain assessed by the McGill questionnaire.ResultsThere were no significant differences in baseline characteristics between the two groups. Both groups showed a significant reduction in back and leg pain at 12 months compared with baseline measurements. No significant differences were found between the groups in effect on both primary (pain) and secondary parameters (SF-36, HADS, EQ-5D, ODI, and McGill pain).ConclusionIn a subgroup of patients with chronic back and leg pain, SCS alone provided similar long-term pain relief and quality-of-life improvement as PNFS in addition to SCS. In patients with refractory low back pain not responding to SCS alone, adding PNFS should be recommended.Clinical Trial RegistrationThe Clinicaltrials.gov registration number for the study is NCT01776749.     

Subcutaneous Stimulation as Add-on Therapy to Spinal Cord Stimulation in Patients With Persistent Spinal Pain Syndrome Significantly Increases the Total Electrical Charge per Second: Aspects on Stimulation Parameters and Energy Requirements of the Implanted Neurostimulators

ObjectiveIn our previous multicenter randomized controlled trial, we demonstrated the clinical effectiveness of peripheral nerve field stimulation (PNFS) as add-on therapy to spinal cord stimulation (SCS) for the treatment of chronic back pain in patients with persistent spinal pain syndrome (PSPS) or failed back surgery syndrome (FBSS). To our knowledge, no previous study has investigated the effect of PNFS as an add-on to SCS on the energy consumption of the implanted neurostimulators. Therefore, in this study, we compared the specific stimulation parameters and energy requirements of a previously unreported group of patients with only SCS with those of a group of patients with SCS and add-on PNFS. We also investigated differences that might explain the need for PNFS in the treatment of chronic low back pain.Materials and MethodsWe analyzed 75 patients with complete sets of stimulation parameters, with 21 patients in the SCS-only group and 54 patients in the SCS + PNFS group. Outcome measures were average visual analog scale score, SCS parameters (voltage, frequency, and pulse width), SCS charge per second, and total charge per second. We analyzed baseline characteristics and differences between and within groups over time.ResultsBoth groups had comparable patient characteristics at baseline and showed a significant decrease in back and leg pain. SCS charge per second did not significantly differ between the groups at baseline or at 12 months. The total charge per second was significantly higher in the active SCS + PNFS group than in the SCS-only group at baseline; in the SCS + PNFS group, this persisted for up to 12 months, and the SCS charge per second and total charge per second increased significantly over time.ConclusionsOur results show that add-on PNFS increases the total charge per second compared with SCS alone, as expected. However, further research is needed because our results do not directly explain why some patients require add-on PNFS to treat low back pain.     

Prospective,Two-part Study of the Interaction Between Spinal Cord Stimulation and Peripheral Nerve Field Stimulation in Patients with Low Back Pain: Development of a New Spinal-Peripheral Neurostimulation Method

Objective: The goal of the study was to assess the efficacy of interaction between spinal cord stimulation (SCS) and peripheral nerve field stimulation (PNFS) and to evaluate a new spinal‐peripheral neuromodulation method for low back pain. Materials and Methods: The prospective two‐part study included patients with low back pain due to failed back surgery syndrome and/or spinal stenosis. In the first part 20 patients were implanted with SCS and PNFS. They selected the best program out of three: SCS alone, PNFS alone, or both together. In the second part another 20 patients with the same implanted leads were selecting between three programs: SCS and PNFS separately, SCS as anode and PNFS as cathode, or in reverse. Results: In the first part 79% of the patients selected simultaneous use of SCS and PNFS. The overall success of the trials was 85%. In the second part communication between SCS and PNFS provided wider coverage of axial pain. The overall success of the trials was 90%. Conclusion: Simultaneous use of SCS and PNFS increase efficacy of both methods for axial back pain. The new SPN method showed great potential in providing coverage for back pain.     

Functional Connectivity Magnetic Resonance Imaging Sequences in Patients With Postsurgical Persistent Spinal Pain Syndrome Type 2 With Implanted Spinal Cord Stimulation Systems: A Safety,Feasibility, and Validity Study

BackgroundChronic pain has been associated with alterations in brain connectivity, both within networks (regional) and between networks (cross-network connectivity). Functional connectivity (FC) data on chronic back pain are limited and based on heterogeneous pain populations. Patients with postsurgical persistent spinal pain syndrome (PSPS) type 2 are good candidates for spinal cord stimulation (SCS) therapy. We hypothesize that 1) FC magnetic resonance imaging (fcMRI) scans can be safely obtained in patients with PSPS type 2 with implanted therapeutic SCS devices and that 2) their cross-network connectivity patterns are altered and involve emotion and reward/aversion functions.Materials and MethodsResting-state (RS) fcMRI (rsfcMRI) scans were obtained from nine patients with PSPS type 2 implanted with therapeutic SCS systems and 13 age-matched controls. Seven RS networks were analyzed, including the striatum.ResultsCross-network FC sequences were safely obtained on a 3T MRI scanner in all nine patients with PSPS type 2 with implanted SCS systems. FC patterns involving emotion/reward brain circuitry were altered as compared with controls. Patients with a history of constant neuropathic pain, experiencing longer therapeutic effects of SCS, had fewer alterations in their connectivity patterns.ConclusionsTo our knowledge, this is the first report of altered cross-network FC involving emotion/reward brain circuitry in a homogeneous population of patients with chronic pain with fully implanted SCS systems, on a 3T MRI scanner. All rsfcMRI studies were safe and well tolerated by all nine patients, with no detectable effects on the implanted devices.     

Combined Spinal Cord and Peripheral Nerve Field Stimulation for Persistent Post‐Herniorrhaphy Pain

Objectives: Chronic post‐hernia pain is a common complication after inguinal herniorrhaphies. Peripheral nerve field stimulation (PNFS) and spinal cord stimulation (SCS) are two new promising treatment modalities. Four patients with persistent neuropathic post‐hernia pain were recruited for this prospective study. Materials and Methods: Electrodes were inserted into the epidural space of the spinal canal and into the subcutaneous tissue in the inguinal region during a single surgical procedure. During a 14‐day trial, double‐blind stimulation was performed via an external stimulator: three days using the spinal electrode (SCS), three days using the inguinal electrode (PNFS), three days using both (SCS + PNFS), and five days off, with an alternating order from patient to patient. During the trial, pain intensity was assessed thrice daily by the visual analog scale. Additionally, pain intensity and quality of life (QOL) were assessed before and after surgical intervention by the Brief Pain Inventory, SF36 scale, and Pain Disability Index. Results: All patients had a marked pain reduction during the trial phase, and this reduction was more prominent when both electrodes were activated simultaneously (p < 0.001). At the late follow‐up, a significant pain reduction and improvement of QOL was observed in three patients. Conclusions: Both SCS and PNFS are effective in treating post‐hernia pain, but the magnitude of pain reduction was more prominent with concomitant stimulation. Combined PNFS and SCS should be considered for patients with a less than optimal response to either SCS or PNFS. More studies are necessary to address the cost‐effect issues of this new approach to treatment.     

Systematic Literature Review of Spinal Cord Stimulation in Patients With Chronic Back Pain Without Prior Spine Surgery

ObjectiveLow back pain is the leading cause of disability worldwide and one of the most common reasons for seeking health care. Despite numerous care strategies, patients with low back pain continue to exhibit poor outcomes. Spinal cord stimulation (SCS) is an evidence-based therapeutic modality for patients with failed back surgery syndrome. For patients without a surgical lesion or history, minimally invasive interventions that provide long-term reduction of chronic back pain are needed. Therefore, we conducted a systematic review of the evidence on SCS therapy in patients with chronic back pain who have not undergone spinal surgery.Materials and MethodsA systematic literature search was performed to identify studies reporting outcomes for SCS in chronic back pain patients (with or without secondary radicular leg pain) without prior surgery using date limits from database inception to February 2021. Study results were analyzed and described qualitatively.ResultsA total of ten primary studies (16 publications) were included. The included studies consistently demonstrated favorable outcomes in terms of pain reduction and functional improvement following SCS therapy. Improvements also occurred in quality of life scores; however, not all studies reported statistically significant findings. Additionally, the studies reported that SCS resulted in high patient satisfaction, reductions in opioid use, and an acceptable safety profile, although these data were more limited.ConclusionFindings suggest that SCS is a promising, safe, minimally invasive, and reversible alternative option for managing chronic back pain in patients who have not undergone spinal surgery.     

Peripheral Nerve Field Stimulation in the Treatment of Postlaminectomy Syndrome after Multilevel Spinal Surgeries

Introduction: Chronic low back pain in patients with postlaminectomy syndrome (PLS) is challenging to treat, especially for patients who have undergone multilevel surgical procedures. Despite conservative therapy and available interventional pain procedures including spinal cord stimulation (SCS) and intrathecal therapies, patients may continue with intractable low back pain. Peripheral nerve field stimulation (PNFS) may represent an effective alternative treatment option for these patients when conventional treatments do not provide adequate relief of intractable low back pain. Methods: Eighteen patients underwent an uneventful PNFS trial with percutaneous placement of four temporary quadripolar leads (Medtronic, Inc., Minneapolis, MN, USA) placed subcutaneously over the lumbar or thoraco‐lumbar area. Results: After experiencing excellent pain relief over the next two days, temporary leads were removed. The patients were implanted with permanent leads and rechargeable or non‐rechargeable generator two to four weeks after temporary lead removal. All patients reported sustained pain relief 12 months after implantation. Discussion: PNFS with use of four vertically orientated leads provides an effective treatment option for patients with PLS after multilevel surgical procedures with intractable low back pain who have failed conservative treatment. PNFS may provide pain relief with advantages over conservative treatments and interventional treatments including SCS and intrathecal therapy. Conclusion: PNFS may be more effective in treating intractable low back pain than SCS in patients with PLS after multilevel spinal surgeries.     

Novel Spinal Cord Stimulation Waveforms for Treating Back and Leg Pain: A Systematic Review and Meta-Analysis of Randomized Controlled Trials

BackgroundSpinal cord stimulation (SCS) has been suggested as a treatment option to improve the quality-adjusted life years of individuals with low back pain. However, previous reviews have some methodologic limitations. This review aims to evaluate the effectiveness of novel SCS waveforms on pain outcomes in patients with low back pain (LBP) compared with traditional SCS or placebo comparator.Materials and MethodsNine electronic data bases, ongoing trials, gray literature, and targeted journals were searched from inception to December 27, 2021. The Cochrane risk of bias and Grading of Recommendation, Assessment, Development, and Evaluations were used to appraise individual and overall evidence. Subjects aged ≥ 18 years with or without previous surgeries and having LBP for at least three months were included. The primary outcome was pain intensity including back or leg pain scores at postintervention. Secondary outcomes comprised decrease in back, leg, and overall pain, and health-related quality of life.ResultsA total of 11 randomized controlled trials (RCTs) involving 955 participants across four countries were included. Our meta-analysis revealed that novel SCS waveform was superior to traditional SCS or placebo comparator for treating leg pain (Z = −2.12, p = 0.03) with a small effect size (Hedges’ g = −0.18, 95% CI: −0.34 to −0.01). Back-pain intensity (g = −0.22, 95% CI: −0.47 to 0.02) and health-related quality of life (g = −0.12, 95% CI: −0.43 to 0.18) were similar between the novel SCS waveform group and the traditional SCS or placebo comparator groups. The meta-regression did not identify any effect of the covariates on back-pain intensity.ConclusionsWith low certainty of evidence, this finding provides a rationale for considering the novel SCS waveform as complements to the usual therapeutic plan. Future trials should adopt well-designed RCTs with larger sample size and follow-up assessment.     

Spinal Cord Stimulation for the Treatment of Chronic Pain in Patients with Lumbar Spinal Stenosis

Objective: Chronic back and leg pain associated with lumbar spinal stenosis (LSS) is common in the elderly. Surgical decompression is usually performed when conservative treatments fail. We present an evaluation of the long‐term outcome of patients suffering from symptomatic LSS treated with spinal cord stimulation (SCS). Materials and Methods: Data were collected prospectively in three independent registries in three European centers. Pooled data were analyzed retrospectively. Changes in pain intensity, functional status, and analgesic medication were compared at baseline and at the last available follow‐up. Demographic data as well as details regarding the implantation procedure and any adverse events were systematically recorded. Results: Data were recorded in 69 patients with a mean follow‐up period of 27 months. All patients showed clinically and statistically significant improvement in pain relief, the visual analog scale decreasing from 7.4 ± 2.3 to 2.8 ± 2.4 (p < 0.05). The use of analgesic medication decreased and the functional status improved. Conclusion: Spinal cord stimulation seems to be effective in the treatment of patients suffering from chronic pain associated with LSS. Being less invasive and reversible, SCS should be considered before surgical decompression, particularly in patients with increased risks associated with back surgery.     

Spinal Cord Stimulation Paradigms and Pain Relief: A Preclinical Systematic Review on Modulation of the Central Inflammatory Response in Neuropathic Pain

ObjectivesSpinal cord stimulation (SCS) is a last-resort treatment for patients with chronic neuropathic pain. The mechanism underlying SCS and pain relief is not yet fully understood. Because the inflammatory balance between pro- and anti-inflammatory molecules in the spinal nociceptive network is pivotal in the development and maintenance of neuropathic pain, the working mechanism of SCS is suggested to be related to the modulation of this balance. The aim of this systematic review is to summarize and understand the effects of different SCS paradigms on the central inflammatory balance in the spinal cord.Materials and MethodsA systematic literature search was conducted using MEDLINE, Embase, and PubMed. All articles studying the effects of SCS on inflammatory or glial markers in neuropathic pain models were included. A quality assessment was performed on predetermined entities of bias.ResultsA total of 11 articles were eligible for this systematic review. In general, induction of neuropathic pain in rats results in a proinflammatory state and at the same time an increased activity/expression of microglial and astroglial cells in the spinal cord dorsal horn. Conventional SCS seems to further enhance this proinflammatory state and increase the messenger RNA expression of microglial markers, but it also results in a decrease in microglial protein marker levels. High-frequency and especially differential targeted multiplexed SCS can not only restore the balance between pro- and anti-inflammatory molecules but also minimize the overexpression/activation of glial cells. Quality assessment and risk of bias analysis of the studies included make it clear that the results of these preclinical studies must be interpreted with caution.ConclusionsIn summary, the preclinical findings tend to indicate that there is a distinct SCS paradigm–related effect in the modulation of the central inflammatory balance of the spinal dorsal horn.     

Spinal Cord Stimulation in Conjunction With Peripheral Nerve Field Stimulation for the Treatment of Low Back and Leg Pain: A Case Series

Background. The treatment of chronic low back and leg pain remains a difficult medical challenge, particularly for patients with postlaminectomy syndrome. While spinal cord stimulation (SCS) has been a significant addition to the available options, it is often inadequate in relieving both the back and leg pain components. We hypothesized that for some patients the combination of SCS with peripheral nerve field stimulation (PNFS) would be a safe, effective alternative that would be more effective than either modality alone. Objective. Our objective was to demonstrate the efficacy of PNFS used in combination with SCS for the treatment of chronic pain syndromes involving the lower back and legs. Study Design. Case series. Methods. A total of 20 patients with chronic low back and leg pain syndromes who had failed conventional therapies underwent implantation of a combination of traditional SCS and PNFS. Leads were placed in the epidural space, as well as superficially in the subcutaneous tissues of the lower back, directly in the region of maximum pain. Patients initially underwent a trial of stimulation to assess response, and a permanent system was implanted if patients reported greater than 50% pain relief during the trial. For some patients, a combination was used at the time of the initial trial. In other cases, the decision to proceed with the combination was made later, either at the time of permanent implant, or later on, after SCS alone failed to adequately control pain. Results. In each case, PNFS was used in combination with traditional SCS for patients with chronic lower back and lower extremity pain. While not all of these patients ultimately proceeded with the combination of SCS and PNFS to control their pain, the majority of patients found the combination better in controlling their overall pain than either modality alone. In addition, using a combined approach at the time of trial provided a noninvasive and effective method of comparing the efficacy of each method, allowing patients to identify the best form of neuromodulation for their particular pain. Conclusions. Due to the availability of 16 contact capacity generators, neurostimulation with multiple leads in various combinations—including both epidural and peripheral nerve field stimulation simultaneously—can be applied safely and effectively. The availability of this combined approach for a trial of stimulation prior to implant allows patients to compare SCS to PNFS and to indicate a preference for one over the other or for the combination. We conclude that PNFS may be used in combination with SCS as a safe and effective alternative treatment for patients with chronic low back and leg pain, and further suggest that the combined approach should be considered as a treatment option for this population.     

One-Year Results of Prospective Research Study Using 10 kHz Spinal Cord Stimulation in Persistent Nonoperated Low Back Pain of Neuropathic Origin: Maiden Back Study

PurposeSpinal cord stimulation (SCS) is a recommended treatment for chronic neuropathic pain. Persistent nonoperative low back pain of neuropathic origin has profound negative impacts on patient’s lives. This prospective, open label, research study aimed to explore the use of SCS in patients with associated features of central sensitisation such as allodynia and hyperalgesia.Materials and MethodsTwenty-one patients with back pain and hyperalgesia or allodynia who had not had prior spinal surgery underwent a SCS trial followed by full implantation. SCS comprised administering electrical impulses epidurally at a frequency of 10 kHz and pulse width of 30 μsec. Patients attended follow-up visits after 6 and 12 months of SCS. Repeated measure ANOVAs/Friedman tests explored change after 6 and 12 months of 10 kHz SCS. Independent sample t-tests/Mann–Whitney U tests examined differences in response after 12 months of 10 kHz SCS.ResultsBack and leg pain, quality of life (QoL), pain-related disability, and morphine equivalence significantly improved compared with baseline following 6 and 12 months of 10 kHz SCS. There were no increases in the consumption of opioids, amitriptyline, gabapentin or pregabalin in any patient. After 12 months of treatment, 52% encountered ≥50% improvement in back pain, 44% achieved remission (0–3 cm back pain VAS), 40% reported ODI scores between 0 and 40 and 60% experienced a reduction of at least 10 ODI points. Patients reporting ≥10-point improvement in ODI had significantly longer pain history durations and experienced significantly greater improvements in back pain, leg pain and QoL than those reporting <10-point improvement in ODI.ConclusionThe 10 kHz SCS improved back and leg pain, QoL, pain-related disability and medication consumption in patients with nonoperative back pain of neuropathic origin. With further research incorporating a sham control arm, the efficacy of 10 kHz SCS in this patient cohort will become more established.     

Spatiotemporal Distribution of Electrically Evoked Spinal Compound Action Potentials During Spinal Cord Stimulation

ObjectivesRecent studies using epidural spinal cord stimulation (SCS) have demonstrated restoration of motor function in individuals previously diagnosed with chronic spinal cord injury (SCI). In parallel, the spinal evoked compound action potentials (ECAPs) induced by SCS have been used to gain insight into the mechanisms of SCS-based chronic pain therapy and to titrate closed-loop delivery of stimulation. However, the previous characterization of ECAPs recorded during SCS was performed with one-dimensional, cylindrical electrode leads. Herein, we describe the unique spatiotemporal distribution of ECAPs induced by SCS across the medial-lateral and rostral-caudal axes of the spinal cord, and their relationship to polysynaptic lower-extremity motor activation.Materials and MethodsIn each of four sheep, two 24-contact epidural SCS arrays were placed on the lumbosacral spinal cord, spanning the L3 to L6 vertebrae. Spinal ECAPs were recorded during SCS from nonstimulating contacts of the epidural arrays, which were synchronized to bilateral electromyography (EMG) recordings from six back and lower-extremity muscles.ResultsWe observed a triphasic P1, N1, P2 peak morphology and propagation in the ECAPs during midline and lateral stimulation. Distinct regions of lateral stimulation resulted in simultaneously increased ECAP and EMG responses compared with stimulation at adjacent lateral contacts. Although EMG responses decreased during repetitive stimulation bursts, spinal ECAP amplitude did not significantly change. Both spinal ECAP responses and EMG responses demonstrated preferential ipsilateral recruitment during lateral stimulation compared with midline stimulation. Furthermore, EMG responses were correlated with stimulation that resulted in increased ECAP amplitude on the ipsilateral side of the electrode array.ConclusionsThese results suggest that ECAPs can be used to investigate the effects of SCS on spinal sensorimotor networks and to inform stimulation strategies that optimize the clinical benefit of SCS in the context of managing chronic pain and the restoration of sensorimotor function after SCI.     

Spinal Cord Stimulation to Treat Low Back Pain in Patients With and Without Previous Spine Surgery

ObjectivesLittle is known about the effects of spinal cord stimulation (SCS) on chronic low back pain (CLBP) patients with no history of previous spine surgery. Using our prospectively collected database, we evaluate improvements in patients with and without previous spine surgery one-year post SCS implantation.Materials and MethodsSubjects completed outcome metrics pre-operatively and one-year post-implantation including Numeric Rating Scale (NRS), McGill Pain Questionnaire (MPQ), Oswestry Disability Index (ODI), Beck’s Depression Inventory (BDI), and Pain Catastrophizing Scale (PCS).ResultsWe enrolled 134 patients; 82 patients had previous spine surgery and 52 patients did not. At one-year post-SCS implantation, patients with previous spine surgery showed improvements in worst pain experienced, least pain experienced, average pain experienced, pain felt currently, MPQ, MPQ sensory, MPQ affective, PCS, PCS helplessness, PCS rumination, PCS magnification, ODI, and BDI scores (p < 0.001, p = 0.005, p < 0.001, p < 0.001, p < 0.001, p < 0.001, p = 0.03, p = 0.01, p = 0.02, p < 0.001, p = 0.05, p < 0.001, p = 0.017, respectively). Likewise, patients without previous spine surgery showed improvements in worst pain experienced, least pain experienced, average pain experienced, pain felt currently, MPQ, MPQ sensory, PCS, PCS helplessness, PCS rumination, PCS magnification, ODI, and BDI scores (p < 0.001, p = 0.005, p < 0.001, p < 0.001, p < 0.001, p < 0.001, p < 0.001, p < 0.001, p < 0.001, p = 0.008, p < 0.001, p < 0.001, respectively). Patients without previous spine surgery showed greater improvements for average pain PCS helplessness (p = 0.01).ConclusionsPatients with and without previous spine surgery showed similar improvements in pain intensity, pain quality, feelings of rumination and magnification, functional disability, and depression severity. SCS can improve CLBP regardless of whether patients have had previous spine surgery.     

Spinal Cord Stimulation in the Treatment of Cancer Pain: A Retrospective Review

ObjectivesSpinal cord stimulation (SCS) involves electrical stimulation of the dorsal spinal cord to disrupt the transmission of ascending pain signals. SCS has been used successfully to manage a variety of chronic pain conditions, but its efficacy in the treatment of pain syndromes in patients with cancer has not been established because most studies have involved a limited number of patients. The purpose of this study was to assess the efficacy of SCS in a large group of patients with cancer.Materials and MethodsA retrospective review was performed for all patients who had SCS trials and implants placed at Memorial Sloan Kettering Cancer Center between 2003 and 2021. Patients were divided into groups based on whether their pain could be directly attributed to cancer or its treatment (cancer dependent, n = 51) and those who had incidental pain unrelated to cancer (cancer independent, n = 22). The cancer-dependent group was further subdivided into those whose pain was directly related to primary tumor invasion or metastasis (cancer related, n = 26) and those whose pain was a result of cancer treatment such as chemotherapy or surgery (treatment related, n = 25). The primary outcomes were changes in pain scores and daily oral morphine equivalents (OMEs) before intervention to one year after implant. Secondary measures included the SCS trial success rate, change in pain scores immediately after the SCS trial, and change in pain scores immediately after the SCS implant.ResultsMost patients in the cancer-dependent pain group (59%) and the cancer-independent pain group (68%) had successful SCS trials and subsequently went on to have SCS implants placed. The patients with cancer-dependent pain as a whole had median reduction of 1.5 points (or 23%) on a 10-point pain score immediately after implant (p = 0.001), with the effect diminishing to a median reduction of 1 point (or 15%) by one year after implant (p = 0.027). The cancer-dependent pain groups did not have a significant reduction in daily OMEs, following implantation (p = 0.30), but the cancer-independent group did have a significant reduction (p = 0.01).ConclusionsSCS can be considered as a treatment modality for patients with cancer whose pain is not adequately controlled with medical therapy or by less invasive interventions.     

Comparison of Paresthesia Mapping With Anatomic Placement in Burst Spinal Cord Stimulation: Long-Term Results of the Prospective,Multicenter, Randomized,Double-Blind,Crossover CRISP Study

ObjectivesSpinal cord stimulation (SCS) is an effective therapy for chronic intractable pain. Conventional SCS involves electrode placement based on intraoperative paresthesia mapping; however, newer paradigms like burst may allow for anatomic placement of leads. Here, for the first time, we report the one-year safety and efficacy of burst SCS delivered using a lead placed with conventional, paresthesia mapping, or anatomic placement approach in subjects with chronic low back pain (CLBP).Materials and MethodsSubjects with CLBP were implanted with two leads. The first lead was placed to cross the T8/T9 disc and active contacts for this lead were chosen through paresthesia mapping. The second lead was placed at the T9/T10 spinal anatomic landmark. Subjects initially underwent a four-week, double-blinded, crossover trial with a two-week testing period with burst SCS delivered through each lead in a random order. At the end of trial period, subjects expressed their preference for one of the two leads. Subsequently, subjects received burst SCS with the preferred lead and were followed up at 3, 6, and 12 months. Pain intensity (visual analog scale), quality-of-life (EuroQol-5D instrument), and disability (Oswestry Disability Index) were evaluated at baseline and follow-up.ResultsForty-three subjects successfully completed the trial. Twenty-one preferred the paresthesia mapping lead and 21 preferred the anatomic placement lead. Anatomic placement lead was activated in one subject who had no preference. The pain scores (for back and leg) significantly improved from baseline for both lead placement groups at all follow-up time points, with no significant between-group differences.ConclusionsThis study demonstrated that equivalent clinical benefits could be achieved with burst SCS using either paresthesia mapping or anatomic landmark-based approaches for lead placement. Nonparesthesia-based approaches, such as anatomic landmark-based lead placement investigated here, have the potential to simplify implantation of SCS and improve current surgical practice.     

Patient Satisfaction With Spinal Cord Stimulation and Dorsal Root Ganglion Stimulation for Chronic Intractable Pain: A Systematic Review and Meta-Analysis

ObjectivesIn the spinal cord stimulation (SCS) and dorsal root ganglion stimulation (DRG-S) literature, the typical primary outcome measure includes pain relief, whether numeric rating scale changes or percentage pain relief, and functional outcomes and patient satisfaction are included as secondary outcomes. This systematic review and meta-analysis aims to determine the rate of patient satisfaction with the use of SCS and DRG-S in the treatment of chronic intractable pain.Materials and MethodsThe study protocol was registered in the PROSPERO International prospective register of systematic reviews. We queried articles from multiple electronic data bases, including MEDLINE, EMBASE, and Cochrane Central Register of Controlled Trials data bases, and hand-searched reference lists of identified publications. All periods were included. Inclusion criteria encompassed randomized controlled trials (RCTs) and prospective observational studies that reported patient satisfaction in patients who underwent SCS or DRG-S. Bias evaluation for the included studies involved appropriate guidelines for each study design (Cochrane risk of bias tool for RCTs and Newcastle-Ottawa scale for observational studies).ResultsOur search strategy identified 242 unique citations, of which nine RCTs and 23 observational studies were included for analysis. Overall, 25 studies comprising 1355 participants were pooled in our quantitative analysis. The pooled proportion of patients who reported satisfaction from all studies was 82.2% (95% CI, 77.8%–86.2%). This finding had high statistical heterogeneity (I² = 74.0%). Subgroup analysis did not reveal differences in satisfaction when studies were stratified based on study design (RCT or observational study) or follow-up period (six, 12, 24, and 36 months).ConclusionsOur results show high levels of patient satisfaction across the SCS and DRG-S literature when these treatment modalities are used for chronic intractable pain, regardless of SCS programming algorithm. However, there is a scarcity of unbiased and/or non–industry-funded prospective studies in the neuromodulation field, and future efforts to expand this area of the SCS and DRG-S literature are greatly needed.     

Spinal Cord Stimulation for the Treatment of Upper and Lower Extremity Neuropathic Pain due to Lyme Disease

Background. Lyme disease is caused by Borrelia, a bacterium transmitted by the bite of a deer tick. A slow developing encephalopathy or an axonal polyneuropathy with distal paresthesia and spinal or radicular pain rarely occurs and can be hard to treat. Materials and Methods. We report here the case of a 44‐year‐old woman with four‐limb, intolerable, neuropathic pain as sequelae to Lyme disease, which was resistant to conservative measures and was treated successfully with concurrent, thoracic, and cervical percutaneous spinal cord stimulation (SCS). Results. After 18 months of therapy and follow‐up, this patient's analgesia, as a result of SCS, continues to be excellent, with almost complete subjective pain relief and cessation of adjuvant analgesic medication. Conclusions. SCS may be efficacious for the treatment of neuropathic pain due to Lyme disease.     

Treatment of Failed Back Surgery Syndrome

Objectives. To evaluate the long‐term results of different therapies for failed back surgery syndrome (FBSS). Materials and Methods. From 1992 to 1997, 49 patients were treated for FBSS. Twenty patients were treated medically. Twenty‐four patients, who did not respond to medical therapy, underwent spinal cord stimulator (SCS) implant and five underwent further spine surgery. All patients were evaluated by VAS, PDI, and the Oswestry Scales before treatment and at follow‐up. Leg pain, back pain, work status or daily activities, drug side effects, and use of analgesic medications after implantation were examined. Follow‐up ranged from 24 to 84 months (mean 42 months). Results. At last follow‐up, the patients treated medically demonstrated good results on leg and low back pain in eight cases; in other cases, good results were transitory and several therapeutic courses were necessary to control the pain. Two patients treated medically had substantial side effects. All but two patients treated with SCS demonstrated good results for their leg pain; whereas those treated for back pain with SCS had poor results. Two patients still needed continuous drug administration. Conclusions. Medical therapy is effective for leg and back pain; nevertheless, several courses of therapy may be necessary. SCS is an effective treatment for leg pain, however, its effectiveness on back pain appears to be inadequate.     

Lumbar and Sacral Nerve Root Stimulation (NRS) in the Treatment of Chronic Pain: A Novel Anatomic Approach and Neuro Stimulation Technique

Objective. The conventional technique used to stimulate the lumbar dermatomes is by stimulation of the dorsal columns of the spinal cord. Until recently, stimulation of nerve roots had not been successfully accomplished. We had performed selective nerve root cannulations for the placement of temporary catheters at cervical, thoracic, lumbar, and sacral levels in chronic pain patients using a caudad rather than craniad approach. We hypothesized that by stimulating the nerve roots we could improve paresthesia coverage in areas which cannot be covered effectively by spinal cord stimulation (SCS). To test this hypothesis, we have performed trials of nerve root stimulation (NRS) in patients who had failed SCS, or who were not candidates for SCS because their pain was otherwise inaccessible to stimulation. Methods. Five patients who had been unresponsive to conservative treatment, surgery, or SCS underwent 7-day trials with NRS. The diagnoses included: ilioinguinal neuralgia, discogenic low back pain, failed back syndrome, vulvodynia, and interstitial cystitis. We collected paresthesia maps, pain maps, pain visual analog scale (VAS) scores, and patient satisfaction ratings. Results. Paresthesia coverage was above 75% in all patients. VAS scores declined from a mean of 9 ± 1.0 to 2.4 ± 2.1 (p < 0.05, n= 5), all 5 patients requested permanent implantation, and 4 have been implanted so far. Conclusions. Lumbar and sacral NRS trials resulted in adequate paresthesia coverage and effective pain relief in all 5 patients. Further clinical trials to evaluate long-term success rates and safety are indicated. Detailed mapping studies are needed to evaluate the relationship between electrode placement and paresthesia patterns as well as the optimal stimulation parameters.