Unilateral thalamic deep brain stimulation for disabling kinetic tremor in multiple sclerosis

Surgical options of multiple sclerosis (MS) tremor treatment are limited and narrowed to thalamotomy or deep brain stimulation of the thalamic nucleus ventralis intermedius. Lack of qualification protocol frequently results in poor outcome.

To determine prospectively the efficacy and safety of unilateral ventralis intermedius deep brain stimulation as a tool to control disabling kinetic arm tremor related to MS.

Neurological and neuropsychological evaluations were performed 1 month and 1 day before surgery and 1, 3, and 6 months after surgery. The evaluation included measurement of tremor and dexterity, Extended Disability Status Scale, Mini Mental State Examination, and quality-of-life assessment. Nine consecutive patients were enrolled in the group. Mean age at the time of surgery was 38.9 ± 9 years; median Extended Disability Status Scale at baseline was 7.1. Mean MS duration was 11.7 years, and mean tremor duration was 6.11 years. Mean postural and kinetic scores and hand capacity were measured.

One month after surgery, median scores off and on stimulation were 12 and 6 for postural tremor, 12 and 10.5 for kinetic tremor score, 12 and 7.5 for manual capacity, and 22 and 20 for functional handicap, respectively. Similar results were 10 and 4, respectively, at the 3-month follow-up. Six months after surgery, median scores off and on stimulation were 10.4 and 4 for postural tremor and 12 and 7.8 for kinetic tremor, respectively.

This prospective study confirms the value and safety of ventralis intermedius deep brain stimulation for treatment of kinetic tremor related to MS. Accurate and precise presurgical qualification plays a key role in successful treatment.