Long-Term Outcome of Spinal Cord Stimulation for Chronic Pain Management

Study Design. This is a retrospective study on 102 patients subjected to implantation of a spinal cord stimulation system for nonmalignant chronic pain management. The study was conducted through an extensive questionnaire and telephone interviews by a neutral third party. All the patients were implanted with a complete spinal cord stimulation system without a preliminary trial with a temporarily implanted electrode. Diagnostic categories were neuropathic pain, failed back syndrome, spinal cord Injury pain, and miscellaneous. Average follow-up was 3.8 years (6 months to 8 years). Patients were divided in two groups: all the implanted patients in the survey (Group A) and the implanted patients who experienced some degree of pain relief with the stimulation (Group B). Group B (80 patients) closely matches previously published series where an initial temporary screening was performed. Results. Twenty-one percent of the patients never experienced any pain relief. Of the remaining 80, 75% were still using the stimulator. Fifty-one percent of the 80 patients were experiencing good to excellent results and 20% moderate results. There was no reduction over time in the amount of pain relief in patients who initially had at least 75% pain relief. Patients with initial pain relief between 50% and 74% observed a moderate reduction in their pain relief after two years. Patients who initially experienced less than 50% pain relief observed a dramatic reduction in their results in the long term follow-up. Psychological screening contributed to the success of the procedure. Conclusions. With proper medical and psychological screening and with demonstrated initial pain relief, spinal cord stimulation remains an effective modality in the long-term management of severe chronic pain.     

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.     

Neuromodulation With Burst and Tonic Stimulation Decreases Opioid Consumption: A Post Hoc Analysis of the Success Using Neuromodulation With BURST (SUNBURST) Randomized Controlled Trial

ObjectivesThe SUNBURST study was a prospective, multicenter, randomized crossover trial of a single device delivering burst and tonic spinal cord stimulation (SCS) for chronic trunk and/or limb pain. We performed a post hoc analysis of opioid consumption at baseline and after device implantation.Materials and MethodsAfter implantation, 100 patients were randomized to one mode (tonic or burst) for 12 weeks, and the other mode for the subsequent 12 weeks. After the crossover period (24 weeks), patients chose their preferred mode and were assessed for one year. We analyzed 69 patients who took opioid medication at baseline. The primary endpoint was opioid consumption in morphine milligram equivalents (MMEs) at baseline and 12 months postimplantation. Subgroup analysis included opioid consumption based on Center for Disease Control markers (<50, 50–90, 90–120, >120 MME/day) and stimulation mode preference.ResultsOpioid consumption at 12 months was lower compared to baseline (53.94 vs. 79.19 MME, MD −25.25, 95% CI −43.77 to 6.73, p = 0.008). By 12 months, 11 of 69 patients (15.9%) discontinued all opioid (p = 0.001). Based on CDC dose markers, the proportion of patients taking >120 MME/day decreased by 61.7% at 12 months postintervention compared to baseline (p = 0.043). Forty-five of 69 patients (65.2%) preferred burst SCS while 15 of 69 patients (21.7%) preferred tonic SCS (p < 0.001).ConclusionA device delivering tonic and burst SCS was associated with decreased opioid consumption after 12 months in patients with chronic trunk and/or limb pain. The proportion of patients reporting the highest opioid intake (>120 MME/day) decreased to a lower CDC dose category by 61.7%, carrying important implications for those at highest risk for opioid-related substance use disorder, overdose, and death.     

Acute vs. Prolonged Screening for Spinal Cord Stimulation in Chronic Pain

Spinal cord stimulation (SCS) was performed to test the hypothesis that pain relief data during acute (15 minute intraoperative) and prolonged (5 day) SCS screening have equivalent predictive value for long‐term successful SCS control of chronic low back pain and/or lower extremity pain. A retrospective series of patients with chronic low back and/or lower extremity pain underwent either percutaneous or open (ie, laminectomy) SCS implantation during which acute intraoperative followed by prolonged screening trials for percentage pain relief (%PR) were performed. Data were analyzed for (a) correlation between positive predictive value (PPV) of acute and prolonged SCS screening for %PR and (b) PPV of acute vs. prolonged screening %PR for long‐term SCS %PR. Fifty‐four patients (male/female = 38/16; mean age ± SEM = 54.2 ± 2.0 years) underwent thoracic (T) (mean level = T9.1 ± 0.4) percutaneous (n = 33) and laminectomy (n = 21) implantation of SCS for acute (15 minute intraoperative) and prolonged (5.0 ± 0.3 days) SCS screening of pain relief. Correlation between successful (> 50%PR) pain relief during acute (n = 53/54, PPV = 98%) and prolonged (n = 47/52, PPV = 90%) screening was significant (Spearman Rank Correlation Coefficient, SRCC = 0.462, p < 0.01). After permanent SCS implantation, at mean follow‐up = 9.4 ± 1.5 months, acute and prolonged SCS screening %PR PPV's were each statistically significant for predicting long‐term SCS relief of chronic pain (n = 31/38, PPV = 82% and n = 31/36, PPV = 86%, SRCC = 0.462 and 0.433, respectively, p < 0.01). We conclude that successful pain relief during acute SCS screening is highly correlated with successful prolonged SCS screening of chronic low back and/or lower extremity pain relief. Acute and prolonged SCS screening appear to have equivalent predictive value for successful long‐term SCS control of chronic low back and/or lower extremity pain. These preliminary results suggest potential justification for eliminating prolonged and retaining acute (intraoperative) SCS screening for selection of permanent SCS implantation candidates.     

Refractory Insomnia in a Patient with Spinal Cord Stimulator Lead Migration

This report outlines a case of refractory insomnia temporally related to migration of cervical spinal cord stimulator leads. To our knowledge this association is previously unreported. The patient had an intractable sleep disturbance until replacement of the leads. A brief review of insomnia and its complex relationship to chronic pain is presented. We hope that this case will stimulate further discussion and possibly bring to light new insights into spinal cord stimulation and insomnia and alert others to this possible clinical association of symptoms.     

Spinal Cord Stimulation for Visceral Pain From Chronic Pancreatitis

Background and Objectives: Spinal cord stimulation (SCS) may reduce pain scores and improve function in patients with various chronic abdominal pain syndromes including chronic pancreatitis. Here described is a large clinical experience in SCS for severe chronic pancreatitis. Methods: SCS was trialed in 30 patients with chronic pancreatitis. SCS trials lasted 7–14 days (median 9 days). SCS lead tips were mostly positioned at the T5 (N= 10) or T6 (N= 10) vertebral level. Results: Twenty‐four patients (80%) reported at least 50% pain relief on completion of the trial. Among these, pre‐trial visual analog scale (VAS) pain scores averaged 8 ± 1.6 (standard deviation) and opioid use averaged 165 ± 120 mg morphine sulfate equivalents. During the trial, VAS pain scores decreased to 3.67 ± 2 cm (p < 0.001, Mann–Whitney Rank Sum Test) and opioid use decreased to 105 ± 101 mg morphine equivalent a day. Six patients failed the trial; one was lost to follow‐up; in three patients after the implantation, the system had to be removed due to infection or lead migration; and 20 were followed for the whole year. For 20 patients followed for the whole year, VAS pain scores remained low (3.6 ± 2 cm; p < 0.001) at one year, as did opioid use (48.6 ± 58 mg morphine equivalents). Conclusions: SCS may be a useful therapeutic option for patients with severe visceral pain from chronic pancreatitis. Prospective trial is warranted.     

Dual Spinal Cord Stimulation for Complex Pain: Preliminary Study

Objectives To retrospectively analyze by indices of success, patients with chronic complex pain, including, axial low back pain, receiving dual spinal cord stimulation (SCS) systems. Methods Eighteen patients with dual spinal cord stimulators have been retrospectively and nonrandomly analyzed. The preponderance of patients in our study group had failed back surgery syndrome (FBSS). Parameters of success of our therapy included reduction of medication, if any, complications, if any, and satisfaction with therapy and improvement in the quality of life, measured by a visual analogical scale (VAS) from 0 to 10. Patients were asked to rate their overall experience with their SCS systems and were divided into four separate groupings according to their overall rating of their therapy. These four groupings included therapy ratings of excellent (70–100%), good (> 50%), fair (< 50%), and poor (< 30%). Satisfaction with therapy and improvement in quality of life were evaluated on a five‐point scale. Patients were asked to rate changes in their quality of life after therapy using the following normative scale: much better, better, no change, worse, and much worse. All the patients in our study were asked if they would repeat their therapy with dual spinal cord stimulation. Results Paresthesia coverage, overlapping the reported painful region, was obtained in 80% of the patients in our study. The VAS decreased an average of 5.6 (range 2–10) after 6 months and 4.9 (range 2–8) at the end of the study. Six patients (37.5%) reported excellent results; four patients (25%) reported good; three (18.7%), fair and poor. Seventy percent of the patients were satisfied with the treatment and reported an increase in their quality of life. Medications were reduced in 75% of the patients. Thirteen (81%) patients with dual lead SCS therapy were willing to repeat the SCS implant procedure. Complications occurred in 43.7%. Conclusions Dual spinal cord stimulation is appropriate and efficacious for treating complex pathology and complex pain that including pain of the low, axial back.     

Spinal Cord Stimulation for Intractable Pain Following Limb Amputation

Objective: Spinal cord stimulation (SCS) by high‐frequency electrical pulses has been used since the early 1970s for relief of chronic intractable pain following limb amputation. The long‐term effectiveness of SCS for amputation‐related pain with ongoing after‐care is reviewed by assessment of all such cases managed over 20 years in the Neurostimulator Clinic at the Royal London Hospital. Materials and Methods: Twelve amputation‐related pain patients had quadripolar paddle electrodes (Resume; Medtronic Inc., Minneapolis, MN, USA) inserted epidurally by laminectomy over the thoracic or cervical dorsal spinal cord and connected to remotely controlled subcutaneously implanted stimulators (Itrel2, Itrel3, Synergy; Medtronic). Results: Two of 12 patients had unsuccessful stimulation, one despite repeated electrode revisions. Two were subsequently lost to follow‐up, one had delayed spontaneous resolution of phantom limb pain, one had a technical fault, and one had gradually waning benefit over 19 years. In the remaining five patients having ongoing follow‐up, self‐reported initial and final magnitudes of pain relief were unchanged, with a mean (SD) of 66% (18.2%). Benefits calculated from local and general visual analogue pain scores were similarly unchanged (initial local 48.8% [18.7%]; final local 50.0% [17.6%]; initial general 60.8% [10.9%]; final general 57.9% [12.3%]). Continued successful stimulation often required frequent changes of stimulating electrode contacts. Revision procedures for technical problems or pain at the battery site were universally successful. Conclusions: Successful SCS in some patients with amputation‐related pain otherwise resistant to treatment indicates that the procedure merits continued use with further efforts to refine technique.     

Lumbar Spinal Cord Stimulation Can Improve Muscle Strength and Gait Independently of the Analgesic Effect: A Case Report

Spinal cord stimulation (SCS) is widely used for pain relief in patients with failed back surgery syndrome (FBSS), and muscle weakness is a common finding in patients with chronic pain. We present here a single case report of a 47‐year‐old woman, who, after SCS for FBSS, had continuous improvement in lower leg muscle strength and gait, but only transient and minimal pain relief. To the authors’ knowledge, this is only the second published case report of significant improvement in “motor” function, independent of the analgesic effect following SCS in FBSS. If SCS, in fact, does improve muscle strength, new strategies for the management of patients with chronic pain might be opened up. Further studies are needed to verify this hypothesis.