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 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.     

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.     

Health‐Related Quality of Life Associated With Pain Health States in Spinal Cord Stimulation for Chronic Neuropathic Pain

ObjectivesA substantial proportion of patients have recently reported pain reduction levels of ≥80% following treatment with Evoked Compound Action Potential (ECAP) spinal cord stimulation (SCS). The additional health-related quality of life (HRQoL) utility gain that can be achieved in this patient group is unclear. The aim of this study is to quantify the HRQoL utility values seen in a remission health state (defined as ≥80% pain reduction) and contrast with more traditional health states of <50% and ≥50% pain relief.Materials and MethodsPain intensity assessed using a 100 mm visual analogue scale (VAS) and EQ-5D-5L questionnaires were collected from 204 patients treated with ECAP SCS for chronic back and leg pain and followed up to 12 months. Utility values were derived using EQ-5D-5L responses crosswalked to EQ-5D-3L. Linear regression models adjusted for baseline utility values and patient demographics were used to compare differences in utility values across health states.ResultsPatients in the remission health state (i.e., ≥80% pain reduction) consistently reported statistically significant greater utility values (+0.09 to +0.15, all p < 0.003) compared to patients reporting ≥50% pain relief at 3- and 12-month follow-up for overall, back, and leg VAS pain. The gain in utility values per percent unit of pain reduction was statistically significant at 3- and 12-month follow-up with a mean increase in HRQoL utility score between 0.003 and 0.005 observed for each percent of pain reduction.ConclusionOur analyses show that patients in a remission health state report statistically and clinically significant better HRQoL than patients experiencing lesser pain relief.     

Conscious Sedation Using Dexmedetomidine During Surgical Paddle Lead Placement Improves Outcome in Spinal Cord Stimulation: A Case Series of 25 Consecutive Patients

ObjectivesDifferent anesthesia techniques are used for surgical implantation of paddle lead electrodes for neurostimulation through a laminectomy. We wanted to evaluate the use of dexmedetomidine as sedative for this procedure in a series of patients. Second, we wanted to verify whether the stimulation pattern and position of the electrode had to be changed during the procedure guided by the patient’s feedback.Material and MethodsTwenty-five consecutive patients received surgical implantation of a spinal cord stimulation electrode under conscious sedation using dexmedetomidine and local anesthesia. We evaluated the effects of the administered drug, the patient comfort, and the adequacy of the stimulation pattern.ResultsTwenty-four patients completed the procedure with only dexmedetomidine and local anesthetic. Infusion was started on average 55 minutes (sd 29) prior to incision. The mean dose of lidocaine was 430 mg (sd 95). There were no significant hemodynamic changes. Median time to reach Modified Aldrete’s score postoperative was 67 minutes (sd 38). In 46% of the patients, the position of the electrode was changed guided by the feedback of the patient. More than half of the patients remember most details of the procedure. Only four patients mentioned substantial discomfort and only three would definitely not want to undergo this procedure again.ConclusionsImplantation of spinal cord stimulation electrodes through a surgical laminectomy using dexmedetomidine is a safe and feasible procedure with adequate comfort for patient and surgeon. This way of working increases the optimal position of the electrode resulting in the most convenient stimulation pattern and avoiding revisions.     

Spinal Cord Stimulation Attenuates Below‐Level Mechanical Hypersensitivity in Rats After Thoracic Spinal Cord Injury

ObjectivesThe burden of pain after spinal cord injury (SCI), which may occur above, at, or below injury level, is high worldwide. Spinal cord stimulation (SCS) is an important neuromodulation pain therapy, but its efficacy in SCI pain remains unclear. In SCI rats, we tested whether conventional SCS (50 Hz, 80% motor threshold [MoT]) and 1200 Hz, low-intensity SCS (40% MoT) inhibit hind paw mechanical hypersensitivity, and whether conventional SCS attenuates evoked responses of wide-dynamic range (WDR) neurons in lumbar spinal cord.Materials and MethodsMale rats underwent a moderate contusive injury at the T9 vertebral level. Six to eight weeks later, SCS or sham stimulation (120 min, n = 10) was delivered through epidural miniature electrodes placed at upper-lumbar spinal cord, with using a crossover design. Mechanical hypersensitivity was examined in awake rats by measuring paw withdrawal threshold (PWT) to stimulation with von Frey filaments. WDR neurons were recorded with in vivo electrophysiologic methods in a separate study of anesthetized rats.ResultsBoth conventional SCS and 1200 Hz SCS increased PWTs from prestimulation level in SCI rats, but the effects were modest and short-lived. Sham SCS was not effective. Conventional SCS (10 min) at an intensity that evokes the peak Aα/β waveform of sciatic compound action potential did not inhibit WDR neuronal responses (n = 19) to graded or repeated electrical stimulation that induces windup.ConclusionsConventional SCS and 1200 Hz, low-intensity SCS modestly attenuated below-level mechanical hypersensitivity after SCI. Inhibition of WDR neurons was not associated with pain inhibition from conventional SCS.     

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.     

Sjögren Syndrome and Spinal Cord Stimulation: A Case Report

Sjögren syndrome is a chronic autoimmune disease. This disease mainly involves salivary and lacrimal glands, although it may also involve the musculoskeletal, respiratory, gastrointestinal, renal, hepato‐biliary, hematological, neurological, vascular, or both systems. Small vessel disease may appear in up to 30% of the cases. We present a case report of a 62‐year‐old female diagnosed with Sjögren syndrome. Systemic associated manifestations of her disease included interstiticial vessel vasculitis with a necrotic, sharp, and painful ulceration in her left heel. Because of refractory pain to common analgesic medical therapies (paracetamol, metamizol, and tramadol), she was referred to our pain unit for evaluation and treatment prior to limb amputation. In our pain unit, a percutaneous posterior spinal cord stimulator (SCS) was placed. SCS clinically reduced her pain by 90% and helped to improve her quality of life and significantly reduced her intake of analgesics. We conclude spinal cord stimulation may be a good alternative to conservative therapies in patients with vasculitis of Sjögren syndrome.