P66. Long term follow-up in bilateral deep brain stimulation of VIM in MS-related tremor

Abstract

Tremor in Multiple Sclerosis is an important cause for disability. As medical treatment often does not provide a sufficient reduction of tremor amplitude, deep brain stimulation is an important option in these patients. Because in previous studies often unilateral stimulation of the VIM was performed, the aim of our retrospective analysis was to evaluate the effect of bilateral stimulation on tremor amplitude, activities of daily living, and due to an additional effect on axial tremor, improvement of global disability (EDSS) and mobility. Data from 22 Patients (12 male an 10 female) were included in our analysis. Surgery was performed at the mean age of 37,7 (range 22–54). The present evaluation included Extended Disability Status Scale (EDSS) preoperatively and 3–6 month after surgery. The clinical tremor rating (Fahn Tolosa Marin Tremor Rating Scale A–C) was scored preoperatively, 3–6 month, 1–2 years, 3–5 years and >5 years postoperatively. After surgery the clinical tremor rating showed a significant improvement of tremor amplitude in the Stim-ON condition compared to baseline parameters before surgery 3–6 month (n = 16; Fahn A p = 0.005; Fahn B p = 0.003) and 1–2 years (n = 12; Fahn A p = 0.013; Fahn B p = 0.068) but no significant improvement 3–5 and >5 years after surgery. Concerning the activities of daily living (Fahn C) no significant change could be observed during the whole period. Two patients, who were dependent on a wheelchair because of severe tremor of the lower extremities, could walk with assistance during a postoperative period of 6 respectively 24 month. Expectedly no significant change of the EDSS score could be observed (mean 6.3; range 3–8) compared to preoperative values (mean 6.1; range 3.5–8.0). 3–6 month after surgery 6.3). Global disability was not changed under treatment with bilateral stimulation of the VIM. A significant improvement of mobility was observed in only two of 22 patients, whereby impaired mobility in only 5 cases was caused by tremor and ataxia. An important problem are the tremor scales which do not appropriately reflect the changes in these most severely handicapped patients. Deep brain stimulation in Patients with Multiple Sclerosis can improve tremor amplitude, but the benefit beyond 2 years is limited. These limitations should be considered in shared decision making with the patient.