Stereotactic ablative and stimulation procedures for treatment of movement disorders

Advances in the understanding of movement disorders and the limitations in their medical treatment have led to a resurgence in surgical treatments. Recent studies of thalamotomy and deep brain stimulation (DBS) for the treatment of essential and parkinsonian tremor demonstrate approximately 80% long-term complete relief of tremor or minimal residual tremor with both procedures. These therapies have a risk of hemorrhage (1-3%) and neurologic complications (20-40%), the latter mostly reversible, with preservation of the therapeutic effect of stimulation in the case of DBS. Such complications were more often permanent in the case of thalamotomy. Other studies have considered pallidotomy of the internal segment of globus pallidus (GPi) for the treatment of bradykinesia and drug-related dyskinesias and fluctuations of medically intractable Parkinson's disease without dementia. Significant improvements in each these symptoms were found at 1 year, with less marked improvements in gait, tremor, and balance. Complications included a less than 3% risk each of hemorrhage, visual field deficit, and weakness. Unresolved questions about this type of surgery include the long-term efficacy of pallidotomy and the efficacy of DBS in the subthalamic nucleus and GPi for treatment of medically intractable Parkinson's disease, but studies are underway. Although the side effects of DBS are often temporary, this mode of therapy assumes the expense and maintenance of an implanted device; controlled, blinded outcome studies of lesioning versus DBS for the treatment of tremor and Parkinson's disease would be useful to compare these therapeutic options.