Neuropsychological Outcomes in Multiple Sclerosis Patients Treated with Deep Brain Stimulation for Tremor

Background : Multiple sclerosis (MS) can often produce a severe cerebellar outflow tremor that is typically poorly responsive to medical management. Deep brain stimulation (DBS) targeted to the ventral intermediate nucleus (VIN) of the thalamus has been shown to suppress the tremor, but long-term outcomes for tremor control in the MS population remain unclear. Furthermore, neuropsychological outcomes for this population have not previously been well described, particularly following DBS. Objectives : The purpose of this study was to assess the long-term outcome of tremor control in our MS patient population following DBS as well as to describe any potential changes in standard neuropsychological measures. Methods : A series of eight patients underwent unilateral or bilateral VIN- thalamic DBS implantation for control of MS related tremor and were followed for a mean of 30.5 months. Postoperative tremor control and pre and postoperative neuropsychological data were retrospectively reviewed. Results : All patients subjectively reported improvement in tremor with stimulation at the most recent available follow-up. Review of neuropsychological outcomes revealed no significant deterioration postoperatively. Conclusions: DBS may improve tremor and decrease disability in the MS population, and does not appear to cause deterioration in neuropsychological outcomes. DBS may be an important adjunct to therapy for MS related tremor.