Spinal Cord Stimulation in a Mouse Chronic Neuropathic Pain Model

Objective. Development of a spinal cord stimulation (SCS) system in a mouse model of chronic neuropathic pain. Materials and Methods. Male C57BL/6 mice (N = 6) underwent a partial ligation of the sciatic nerve. Development of mechanical hyperalgesia was tested using the withdrawal response to tactile stimuli with the von Frey test. An SCS system was implanted on day 14. On day 16, the mice were stimulated for 30 min (f = 50 Hz; pulse width 0.2 msec and stimulation at 2/3 of motor threshold). Repeated measure analysis of variance (anova ) and paired Student's t‐test with Bonferroni correction were used to evaluate the development of mechanical hyperalgesia and the therapeutic effect of SCS. Results. Five out of six mice developed marked mechanical hyperalgesia in the nerve‐lesioned paw that persisted for the duration of the study (16 days). No changes contralateral to the injury were observed. In four out of five mice, a successful implantation of the electrodes followed by stimulation was achieved. Then, SCS resulted in a fast and robust increase of withdrawal threshold back to pre‐injury levels. After termination of the SCS, the withdrawal threshold of the ipsilateral paw slowly decreased. No effect of SCS on the contralateral paw was noted. Conclusion. The development of a mouse SCS system is described that is practical in use, is reproducible, and shows a comparative therapeutic effect in treatment of chronic neuropathic pain as reported in rat.     

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.     

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.     

Sacral Nerve and Spinal Cord Stimulation for Intractable Neuropathic Pain Caused by Spinal Cord Infarction

Central cord pain is very difficult to relieve, even with the many kinds of medical and surgical treatments available. Following spinal cord infarctions, central cord pain can develop. The problems that may arise could include limb pain, pelvic pain, difficulties voiding, and difficulties defecating. We are reporting a case of central cord pain caused by a spinal cord infarction of the conus medullaris. Limb pain was reduced by spinal cord stimulation. Voiding and defecation difficulties and pelvic pain were reduced by sacral nerve stimulation. Thus, in a case involving both intractable limb and pelvic pain, a combination therapy of these two stimulations might be an effective treatment modality.     

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.     

Pulse Intensity Effects of Burst and Tonic Spinal Cord Stimulation on Neural Responses to Brushing in Patients With Neuropathic Pain

ObjectivesTonic spinal cord stimulation (SCS) is accompanied by paresthesia in affected body regions. Comparatively, the absence of paresthesia with burst SCS suggests different involvement of the dorsal column system conveying afferent impulses from low-threshold mechanoreceptors. This study evaluated cortical activation changes during gentle brushing of a pain-free leg during four SCS pulse intensities to assess the effect of intensity on recruitment of dorsal column system fibers during burst and tonic SCS.Materials and MethodsTwenty patients using SCS (11 burst, nine tonic) for neuropathic leg pain participated. Brushing was administered to a pain-free area of the leg during four SCS intensities: therapeutic (100%), medium (66%), low (33%), and no stimulation. Whole-brain electroencephalography was continuously recorded. Changes in spectral power during brushing were evaluated using the event-related desynchronization (ERD) method in theta (4–7 Hz), alpha (8–13 Hz), and beta (16–24 Hz) frequency bands.ResultsBrushing was accompanied by a suppression of cortical oscillations in the range 4–24 Hz. Stronger intensities of burst and tonic SCS led to less suppression of 4–7 Hz and 8–13 Hz bands in parietal electrodes, and in central electrodes in the 16–24 Hz band, with the strongest, statistically significant suppression at medium intensity. Tonic SCS showed a stronger reduction in 4–7 Hz oscillations over right sensorimotor electrodes, and over right frontal and left sensorimotor electrodes in the 8–13 Hz band, compared to burst SCS.ConclusionsResults suggest that burst and tonic SCS are mediated by both different and shared mechanisms. Attenuated brushing-related ERD with tonic SCS suggests a gating of cortical activation by afferent impulses in the dorsal column, whereas burst may engage different pathways. Diminished brushing-related ERD at medium and therapeutic intensities of burst and tonic SCS points towards a nonlinear effect of SCS on somatosensory processing.     

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 in Pregnancy: A Literature Review

Objective: Currently, the use of spinal cord stimulation (SCS) therapy is not recommended in pregnancy because the effects of SCS on the pregnancy and developing fetus are unknown. However, many SCS recipients are women of childbearing age who may later become pregnant. The purpose of the present report is to review and summarize the existing literature on the use of SCS therapy during the prenatal period. Methods: We first present the case of a 38‐year‐old woman from our center who became pregnant after receiving an SCS implantation. We then provide a synopsis of previous reports that were identified in a literature search. We highlight the key findings from these cases as they relate to the course of pregnancy, fetal development, labor and delivery management, fertility, and technical complications. Results: In our literature review, we identified 12 cases of pregnancy in 8 women. To these we add the present case. Conclusions: Women of childbearing age who are candidates for SCS implantation should be tested for pregnancy prior to implantation surgery. They also should be informed about the limited state of our scientific knowledge regarding the impact of this technology on reproductive health. For patients already implanted with SCS, decisions about ongoing use in the event of pregnancy should be made on an individual basis after a careful consideration of potential risks and benefits.