gms | German Medical Science

Tremor in patients with multiple sclerosis (MS) is more difficult to treat with VIM (nucleus ventero-intermedius) deep brain stimulation (DBS) than essential or parkinsonian tremor. We retrospectively analyzed short-term success and long-term outcome in our series of MS patients who received VIM stimulation and discuss strategies for the prediction of a good functional outcome.

Fourteen MS patients (8 female, 6 male, mean age 41 years, all chronic progressive course of the disease) were operated on between 1997 and 2002. Patients were eligible for surgery when a disabling postural or intention tremor of one or both upper extremities was present. Exclusion criteria were midbrain tremor, grossly impaired sensory or motor functions of the hands and major cognitive deficits. Functional outcome was assessed with a standardized questionnaire and tremor-reduction was measured with a motion-tracking device.

Five patients received bilateral and five patients unilateral implantations. Four patients received no implantation because of unsuccessful test stimulation. In 5 patients, the tremor was stopped completely, in the remaining a marked reduction was observed. Functional outcome showed an improvement of over 60% in all patients postoperatively. Only 30% of patients who received electrodes had a sustained improvement lasting longer than 2 years. These patients had minimal progression of the underlying disease. All patients who underwent DBS for their MS-induced tremor would undergo the procedure again.

We conclude from our data that DBS of the VIM is effective in selected patients with MS-tremor. Long-term success is limited due to progressiveness of the underlying disease. Severity of the initial symptoms and the rate of the disease progression might be predictors for an unfavorable long-term outcome.