Thalamic Stimulation in Patients with Multiple Sclerosis

OBJECTIVE: To assess tremor control and side effects in patients with multiple sclerosis (MS) treated with chronic thalamic stimulation for relief of upper extremity tremor. METHODS: Five patients were studied before and after thalamic placement of a deep brain stimulation (DBS) system. Preoperative and postoperative evaluation included magnetic resonance imaging, Extended Disability Status Scale (EDSS), the Bain-Finchley visual analog scale for tremor, video recording and neuropsychological testing. Stereotactic targeting of the Vim nucleus was done using computed tomography; intraoperative testing was done under local anesthesia before permanent implantation. RESULTS: Functionally useful tremor suppression was obtained in 3/5 patients. Neuropsychological deficits of higher cortical function, memory and visuospatial coordination were observed in all patients before surgery; in 1 patient with improved postoperative visuospatial coordination, worsened memory was found. New brainstem plaque formation was seen several weeks after surgery in 1 patient who had an acute worsening of MS which improved after high-dose intravenous steroids. CONCLUSIONS: Chronic thalamic stimulation may help selected patients with MS-induced tremor. Given the complexity of their underlying illness, patients must be selected carefully, and long-term follow-up is vital to evaluate the true utility of DBS.