Thalamic deep brain stimulation for tremor among multiple sclerosis patients

Disabling tremor might be the main cause of disability of multiple sclerosis (MS) patients. Neuromodulation with deep brain stimulation of the thalamic nucleus ventralis intermedius (Vim DBS) is a well accepted method of neurosurgical treatment of tremor related to essential tremor or Parkinson disease. Vim DBS is not widely used to control MS tremor.

Five MS patients with tremor (3 females and 2 males) were treated with Vim DBS. Age at implantation was 37 ± 5 years. MS lasted from 5 to 12 years (mean 6) and tremor was the main cause of disability of those patients from 2 to 5 years (mean 3) before surgery. Clinical condition of the group was evaluated with spirography, the modified Fahn scale and the modified Activity of Daily Living (ADL) scale. Evaluations were performed before surgery and 3 months after surgery. MRI exclusion criteria were the presence of a thalamic hyperintense signal in T2-weight-ed images or ventricular enlargement. The procedures of implantation were performed under local and general anaesthesia.

Intensity of contralateral limb tremor during intraoperative macrostimulation was reduced in the whole group. The therapeutic effect of DBS was maintained at three-month follow-up. Mean contralateral limb tremor reduction was 40%. Mean ADL score improved by 18%. No mortality or morbidity was reported in the group.

The study confirms the value and safety of Vim DBS for treatment of MS-related tremor. Further study on a larger population and introduction of a qualification protocol might increase efficacy of the treatment.