Surgical therapy for multiple sclerosis tremor: a 12-year follow-up study

Background and purpose: Severe multiple sclerosis (MS) tremor causes disability poorly responsive to medication. Deep brain stimulation (DBS) or thalamotomy can suppress tremor, but long-term outcomes are unclear. Methods: Nine patients with MS tremor underwent disability measures at baseline and 12 months post-surgery (six thalamotomy, three DBS) in 1997-1998 (previously reported, Matsumoto et al., Neurology 2001;57:1876-82). We report the prospective 12-year follow-up of this cohort for tremor, disability, and death. Results: Surgery was initially successful in all. Tremor recurred in all patients within median 3 months, although two DBS patients were tremor-free for 5 years. Median tremor-free survival (tremor-free time/survival time) was 4.3%. At 12-year follow-up, four survivors (two thalamotomy, two DBS) (Expanded Disability Status Scale scores 8-8.5) were severely disabled. Five patients were dead (four thalamotomy, one DBS) median 5.8 years post-operative. Conclusions: Surgery benefit for severe tremor was overall short-lived (median 3 months), with long-term poor prognosis. Although two DBS patients had sustained 5-year tremor-suppression, the observed progressive disability and death in this cohort bear importance for long-term success in future MS tremor surgery trials.