Mechanisms of spinal cord stimulation in neuropathic pain

The understanding of the mode of action of spinal cord stimulation (SCS) as treatment of neuropathic pain is still fragmentary. SCS evolved from the gate-control theory postulating a spinal modulation of noxious inflow, but there is little evidence that SCS influences nociceptive pain; pain relief in peripheral vascular disease and angina pectoris is presumably secondary to other SCS effects. In man, SCS may effectively abolish both continuous and evoked pain (tactile/thermal allodynia) whereas induced, acute nociceptive pain is unaffected. Recent SCS studies performed on rat models of mononeuropathy have demonstrated a preferential effect on A beta fiber mediated functions, and the hyperexcitability of wide-dynamic-range dorsal horn neurons was attenuated. These effects were coupled to increased release of GABA and reduced glutamate and aspartate release in the dorsal horn. Intrathecal administration of GABA, baclofen and adenosine enhanced the SCS effect on tactile allodynia even in previously non-responsive rats. Preliminary results indicate that gabapentin may have a similar effect. GABAergic and adenosine-related mechanisms conceivably represent only examples of a number of putative receptor systems involved in SCS. Clinical trials have been initiated exploring the possibility to improve the efficacy of SCS by concomitant pharmacotherapy.     

Quantitative Sensory Testing in Patients With Chronic Unilateral Radicular Neuropathic Pain and Active Spinal Cord Stimulation

Objectives. Spinal cord stimulation (SCS) is an effective treatment option for chronic radicular neuropathic pain syndromes. This prospective study was performed to examine the peripheral effects of SCS on sensation using quantitative sensory testing (QST). Materials and Methods. We measured two consecutive QST measurements for thermal, tactile‐static, tactile‐dynamic, vibratory, and pain sensation of the lower limbs in seven patients with chronic unilateral radicular neuropathic pain who underwent SCS implantation for their pain. Measurements were performed when SCS was turned off and once again during SCS and subsequent reduced pain levels. Results. Baseline QST demonstrated significantly increased thresholds for tactile and warm and cold detection in the pain area. With SCS active, a significant reduction of the cold and warm perception and mechanical detection thresholds was found on the painful side (p < 0.01). Although not significant (p > 0.01), altered sensory thresholds with active SCS also were found at the healthy side where no paresthesias were felt. Conclusion. SCS leads to bilateral subclinical effects even if the evoked paresthesias are only unilateral. Pain perception thresholds are not altered with therapeutic SCS.     

Spinal Cord Stimulation for Neuropathic Pain in England From 2010 to 2020: A Hospital Episode Statistics Analysis

ObjectivesSpinal cord stimulation (SCS) is a recognized intervention for the management of chronic neuropathic pain. The United Kingdom National Institute of Health and Care Excellence has recommended SCS as a management option for chronic neuropathic pain since 2008. The aim of this study is to undertake an assessment of SCS uptake across the National Health Service in England up to 2020.Materials and MethodsHospital Episode Statistics were obtained for patients with neuropathic pain potentially eligible for SCS and patients receiving an SCS–related procedure. Data were retrieved nationally and per region from the years 2010–2011 to 2019–2020.ResultsThere were 50,288 adults in England attending secondary care with neuropathic pain in 2010–2011, increasing to 66,376 in 2019–2020. The number of patients with neuropathic pain with an SCS procedure increased on a year-to-year basis until 2018–2019. However, less than 1% of people with neuropathic pain received an SCS device with no evidence of an increase over time when considering the background increase in neuropathic pain prevalence.ConclusionOnly a small proportion of patients in England with neuropathic pain potentially eligible for SCS receives this intervention. The recommendation for routine use of SCS for management of neuropathic pain has not resulted in an uptake of SCS over the last decade.     

Spinal Cord Stimulation With Hybrid Lead Relieves Pain in Low Back and Legs

Objective: The failed back surgery syndrome (FBSS) is the most common chronic pain syndrome. Whereas it is relatively easy to achieve pain relief in the lower limbs of FBSS patients with spinal cord stimulation (SCS), it is difficult to manage low back pain with SCS. The performance of a paddle‐shaped SCS lead that can be inserted surgically as well as percutaneously (a hybrid lead) was evaluated in a prospective study on the relief of low back pain and leg pain in patients with FBSS. Materials and Methods: Patients with FBSS being eligible for SCS were enrolled in the study, and a hybrid lead was placed surgically. Outcome measures included pain scores for low back and leg pain assessed by visual analog scale (VAS), pain medication, and patient satisfaction. These scores were assessed before and at regular intervals after implantation. Results: It was shown that a single hybrid lead, generally positioned over the physiological midline of the spinal cord, is capable of alleviating both low back and leg pain in patients with FBSS. Forty‐five subjects were eligible for SCS and received trial stimulation. Forty‐two of them had a successful trial period and were converted to a permanent system. Their average VAS score at baseline was 8.0 for lower limb pain and 7.5 for low back pain. After six months of SCS, these average VAS scores were reduced to 3.2 and 3.5, respectively, and also pain medication was reduced significantly. Conclusion: SCS with a hybrid lead in subjects with FBSS is safe, and causes significant pain relief in both the low back and the lower limbs.     

Estimulación de la médula espinal: más allá del manejo del dolor

IntroductionThe gate control theory of pain was the starting point of the development of spinal cord stimulation (SCS). We describe the indications for the treatment in pain management and other uses not related to pain.DevelopmentThere are currently several paradigms for SCS: tonic, burst, and high frequency. The main difference lies in the presence of paraesthesias. SCS is most beneficial for treating neuropathic pain. Patients with failed back surgery syndrome show the best response rates, although a considerable reduction in pain is also observed in patients with complex regional pain syndrome, diabetic neuropathy, radiculopathy, and low back pain without previous surgery. Phantom pain or pain related to cardiovascular or peripheral vascular disease may improve, although there is a lack of robust evidence supporting generalisation of its use. SCS also improves cancer-related pain, although research on this issue is scarce. Non-pain-related indications for SCS are movement disorders, spasticity, and sequelae of spinal cord injury. The main limiting factors for the use of SCS are mechanical complications and the cost of the treatment.ConclusionIn its 50-year history, SCS has progressed enormously. The perfection of hardware and software may improve its effectiveness and reduce the rate of complications. Indications for SCS could include other diseases, and its use could be expanded, if the costs of the technology are reduced.     

Mechanisms of spinal cord stimulation in neuropathic pain

Abstract

The understanding of the mode of action of spinal cord stimulation (SCS) as treatment of neuropathic pain is still fragmentary. SCS evolved from the gate-control theory postulating a spinal modulation of noxious inflow, but there is little evidence that SCS influences nociceptive pain; pain relief in peripheral vascular disease and angina pectoris is presumably secondary to other SCS effects. In man, SCS may effectively abolish both continuous and evoked pain (tactile/thermal allodynia) whereas induced, acute nociceptive pain is unaffected. Recent SCS studies performed on rat models of mononeuropathy have demonstrated a preferential effect on AB fiber mediated functions, and the hyperexcitability of wide-dynamic-range dorsal horn neurons was attenuated. These effects were coupled to increased release of CABA and reduced glutamate and aspartate release in the dorsal horn. Intrathecal administration of GABA, baclofen and adenosine enhanced the SCS effect on tactile allodynia even in previously non-responsive rats. Preliminary results indicate that gabapentin may have a similar effect. GABAergic and adenosine-related mechanisms conceivably represent only examples of a number of putative receptor systems involved in SCS. Clinical trials have been initiated exploring the possibility to improve the efficacy of SCS by concomitant pharmacotherapy. [Neurol Res 2000; 22: 28S-292]     

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.     

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.     

Spinal Cord Stimulation for Pain Treatment After Spinal Cord Injury

In addition to restoration of bladder, bowel, and motor functions, alleviating the accompanying debilitating pain is equally important for improving the quality of life of patients with spinal cord injury(SCI). Currently,however, the treatment of chronic pain after SCI remains a largely unmet need. Electrical spinal cord stimulation(SCS) has been used to manage a variety of chronic pain conditions that are refractory to pharmacotherapy. Yet, its efficacy, benefit profiles, and mechanisms of action in SCI pain remain elusive, due to limited research, methodological weaknesses in previous clinical studies, and a lack of mechanistic exploration of SCS for SCI pain control. We aim to review recent studies and outline the therapeutic potential of different SCS paradigms for traumatic SCI pain. We begin with an overview of its manifestations,classification, potential underlying etiology, and currentchallenges for its treatment. The clinical evidence for using SCS in SCI pain is then reviewed. Finally, future perspectives of pre-clinical research and clinical study of SCS for SCI pain treatment are discussed.     

Spinal cord stimulation: a seven-year audit.

OBJECTIVE: To evaluate the outcome and complications of spinal cord stimulation (SCS) for chronic neuropathic pain in an Australian population. MATERIALS AND METHODS: An independent researcher retrospectively examined the records of 138 patients trialing SCS between 1995 and 2002 at our institution. Information collected included pain relief, ability to perform activities of daily living (ADLs), return to work and reduction in opiate analgesia. Clinical, psychological, demographic and financial data were also collected. RESULTS: Of 138 patients who trialed SCS, 103 (74.7%) achieved a greater than 50% reduction in their pain and proceeded to permanent implantation. At 1 year following permanent implantation, 84.4% of these still had a reduction in their pain by greater than 50%. The majority of patients, 59.1%, stated that their analgesia was good (50-74% pain reduction). All patients required opiate analgesics prior to SCS implantation, but this fell to 54.6% after SCS implantation. Additionally, 73.6% had a significant improvement in their ability to perform ADLs and 24% of patients were able to return to work. CONCLUSION: SCS is an effective treatment in the control of chronic neuropathic pain, particularly in combination with comprehensive medical management within a multidisciplinary pain management centre.     

脊髓电刺激治疗神经病理性疼痛的测试效果及其影响因素分析

目的探讨采用脊髓电刺激(SCS)治疗神经病理性疼痛(NP)的测试效果及其影响因素。方法回顾性分析2012年1月至2019年12月首都医科大学宣武医院功能神经外科采用SCS治疗的81例NP患者的临床资料。对所有患者选择双极刺激模式,频率为30~60 Hz,脉宽为180~260μs,电压为0.5~2.0 V。以疼痛改善率作为SCS测试是否有效的主要评估指标,计算公式为:疼痛改善率=[术前视觉模拟评分(VAS)-术后VAS]/术前VAS×100%;其中疼痛改善率>50%为测试有效,≤50%为测试无效。采用单因素和多因素logistic回归分析法分析影响NP患者SCS测试效果的危险因素。结果81例患者均成功植入电极。81例患者术后疼痛改善率为(45.9±2.9)%;术后VAS为(4.5±2.5)分,较术前[(8.3±1.2)分]显著下降(t=13.67,P<0.01)。根据SCS测试有效的评估标准,45例患者为测试有效,36例为测试无效;测试有效率为55.6%(45/81)。单因素分析结果显示,年龄、性别、病程、术前VAS、病因、疼痛侧别及疼痛区感觉均不是SCS测试效果的影响因素(均P>0.05),而疼痛部位是SCS测试效果的影响因素(P<0.05)。进一步多因素logistic回归分析结果显示,疼痛位于下肢是影响SCS测试效果的保护因素(OR=3.14,95%CI:1.26~7.83,P=0.013)。结论采用SCS治疗NP的测试有效率较高;疼痛位于四肢,特别是下肢的NP患者测试效果较好。     

Allodynia,Hyperalgesia, (Quantitative) Sensory Testing and Conditioned Pain Modulation in Patients With Complex Regional Pain Syndrome Before and After Spinal Cord Stimulation Therapy

ObjectivesComplex regional pain syndrome (CRPS) is a chronic debilitating disease characterized by sensory abnormalities. Spinal cord stimulation (SCS) is an effective therapy for CRPS, but few studies have investigated the effects of SCS therapy on sensory characteristics. Therefore, this study investigated the effect of SCS on allodynia, hyperalgesia, electrical quantitative sensory testing (QST) parameters, and conditioned pain modulation (CPM) effect.Materials and MethodsThis study is part of a multicenter randomized controlled trial (ISRCTN 36655259). Patients with CRPS in one extremity and eligible for SCS were included. The outcome parameters allodynia (symptom and sign), hyperalgesia (symptom), sensory thresholds with QST, CPM effect, and pain scores were tested before and after three months of SCS (40-Hz tonic SCS). Both the CRPS-affected extremity and the contralateral, clinically unaffected extremity were used to test three sensory thresholds with electrical QST: current perception threshold (CPT), pain perception threshold (PPT), and pain tolerance threshold (PTT). The PTT also was used as a test stimulus for the CPM paradigm both before and after the conditioning ice-water test. Nonparametric testing was used for all statistical analyses.ResultsIn total, 31 patients were included for analysis. Pain, allodynia (sign and symptom), and hyperalgesia (symptom) were all significantly reduced after SCS therapy. On the unaffected side, none of the QST thresholds (CPT, PPT, and PTT) was significantly altered after SCS therapy. However, the CPT on the CRPS-affected side was significantly increased after SCS therapy. A CPM effect was present both before and after SCS.ConclusionsStandard 40-Hz tonic SCS significantly reduces pain, hyperalgesia, and allodynia in patients with CRPS. These findings suggest that SCS therapy should not be withheld from patients who suffer from allodynia and hyperalgesia, which contradicts previous findings derived from retrospective analysis and animal research.ISRCTN Registry: The ISRCTN registration number for the study is ISRCTN 36655259.     

Spatial Filtering of Electroencephalography Reduces Artifacts and Enhances Signals Related to Spinal Cord Stimulation (SCS)

ObjectivesHow spinal cord stimulation (SCS) in its different modes suppresses pain is poorly understood. Mechanisms of action may reside locally in the spinal cord, but also involve a larger network including subcortical and cortical brain structures. Tonic, burst, and high-frequency modes of SCS can, in principle, entrain distinct temporal activity patterns in this network, but finally have to yield specific effects on pain suppression. Here, we employ high-density electroencephalography (EEG) and recently developed spatial filtering techniques to reduce SCS artifacts and to enhance EEG signals specifically related to neuromodulation by SCS.Materials and MethodsWe recorded high-density resting-state EEGs in patients suffering from pain of various etiologies under different modes of SCS. We established a pipeline for the robust spectral analysis of oscillatory brain activity during SCS, which includes spatial filtering for attenuation of pulse artifacts and enhancement of brain activity potentially modulated by SCS.ResultsIn sensor regions responsive to SCS, neuromodulation strongly reduced activity in the theta and low alpha range (6–10 Hz) in all SCS modes. Results were consistent in all patients, and in accordance with thalamocortical dysrhythmia hypothesis of pain. Only in the tonic mode showing paresthesia as side effect, SCS also consistently and strongly reduced high-gamma activity (>84 Hz).ConclusionsEEG spectral analysis combined with spatial filtering allows for a spatially and temporally specific assessment of SCS-related, neuromodulatory EEG activity, and may help to disentangle therapeutic and side effects of SCS.     

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.     

The Effect of Spinal Cord Stimulation,Overall, and the Effect of Differing Spinal Cord Stimulation Technologies on Pain,Reduction in Pain Medication,Sleep, and Function

Background. Spinal cord stimulation (SCS) is effective in reducing pain from a number of differing medical conditions that are refractory to other, more conservative treatments. Much is written in the literature regarding efficacy and safety of SCS; however, no one to our knowledge has compared and reported safety and efficacy of SCS when using differing manufactured SCS devices. We undertook such a preliminary evaluation. Methods. Charts from the years 2001–2005 of our clinic's patients who had undergone trials and placement of permanent SCS systems were selected for review. All patients who had received either an Advanced Bionics SCS system (Advanced Bionics, Valencia, CA, USA), an Advanced Neuromodulation Systems (ANS) SCS system (ANS, Plano, TX, USA), or a Medtronic SCS system (Medtronic, Inc., Minneapolis, MN, USA) were given a survey to complete for data analysis. Patients were categorized into three groups: those patients having received a Medtronic (Mdt) SCS system, those patients having received an Advance Bionics (ABi) SCS system, and those patients having received an Advance Neuromodulation Systems (ANS) SCS system. Data, limited to volunteers, who gave their written consent, were analyzed for efficacy and complications. Differences in outcomes and safety were analyzed overall and according to manufacturer. Results. Eighty surveys were mailed out to 80 patients and 30 surveys were completed and returned, a return and completion rate of 37.5%. All patients showed improvement in all aspects including pain relief, sleep, functional activities, and medication use for pain control. When comparing outcomes of SCS from the three different companies, there was no significant statistical difference in average percentage pain relief, sleep improvement, and medication needed for pain control. However, there was a statistically different less change in functional improvement in the ABi group when compared to patients in the Mdt and ANS groups. Conclusions. Spinal cord stimulation improves pain, sleep, and function in patients with intractable pain. Because of the low number of patients evaluable in this study, we believe that conclusions should not be made regarding the effect of technology on outcomes or safety. We believe that an analysis of this type in larger populations is warranted to understand the role, if any, that present‐day technology has on outcomes of SCS.     

Multiple Lead Spinal Cord Stimulation for Chronic Mechanical Low Back Pain: A Comparative Study with Intrathecal Opioid Drug Delivery

The objective of this paper is to assess the outcome of implanted multiple thoracolumbar lead spinal cord stimulation (SCS) in mechanical back pain without prior spinal surgery. These results are compared with intrathecal opioid drug delivery (ITDD). An anonymous third party patient questionnaire study of pain relief, function and psychosocial quality of life measures (recorded on 11‐point numerical rating scales) for 12 patients with SCS and 13 with ITDD was used. Pain was significantly reduced with multiple lead SCS from a median of 9.0–6.5 (p < 0.01) and with ITDD from a median of 8.5–5.5 (p < 0.01). There was a trend towards greater reduction in pain in the ITDD group compared with the SCS group (pain differences 4.5 and 2.6, respectively) but this did not reach statistical significance. The majority of psychosocial quality of life measures were significantly more improved in the ITDD group compared with the SCS group (p < 0.05). We conclude that multiple‐lead SCS improves mechanical back pain in patients unresponsive to more conservative measures. However, ITDD provides significantly more improved quality of life measures, with a trend towards greater pain reduction than SCS.     

Thermogram in spinal cord stimulation with complex regional pain syndrome and a review of the literature

Introduction: Spinal cord stimulation (SCS) is an efficient procedure for treatment of intractable pain. Methods: We present a patient who underwent SCS lead placement for severe left lower extremity pain. The patient had experienced good pain. He underwent thermographic imaging before, just after and ten days later of procedure. Results: Thermogram study revealed from blue color (hypothermic) pattern at before procedure to reddish or pink color (hyperthermic) pattern at ten days later. Discussion: SCS may be increase microcirculation and seems to have sympatholytic effects. Conclusion: We experienced that improvement of blood flow as result of SCS in CRPS.     

Successful Long‐Term Outcomes of Spinal Cord Stimulation Despite Limited Pain Relief During Temporary Trialing

Objectives. In spinal cord stimulation (SCS) therapy, limited pain relief during the temporary trial period is generally considered to be predictive of poor long‐term benefit. To validate or refute this perception, the long‐term outcomes of subjects who reported less than 50% pain relief during a temporary SCS trial were examined. Materials and Methods. Twelve subjects with intractable pain underwent implantation of trial SCS systems. After a trial period in which they reported less than 50% pain relief, they each received a permanent SCS implant. Pain ratings and complications were tracked for 6–18 months. Results. At the end of the temporary trial period, the average pain relief was 21%; no subject reported 50% or better pain relief. More favorable outcomes were reported after activation of the permanent system, however. At all follow‐up time points, at least a third of the subjects reported better than 50% pain relief, and the average pain relief varied over time between 44% and 83%. All complications were readily resolved and no subjects withdrew from the study. Conclusions. Although SCS provided limited pain relief during the trial period, efficacy was more satisfactory after permanent implantation. Several subjects went on to experience nearly complete pain relief for up to 18 months (the maximum follow‐up visit for study purposes), and no subject chose to discontinue SCS therapy. SCS appears to be a viable treatment option for patients who fail trials, raising some doubt as to the predictive sensitivity and specificity of the trial period. Thus, although outcome of a temporary trial period may be suggestive of later efficacy with SCS, it may not be the sole predictor of success. Alternatively, the arbitrary benchmark of 50% pain relief that is typically used to define the success of a temporary trial may be too stringent and unreliable.     

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.