Chronic deep brain stimulation for segmental dystonia.

Fourteen consecutive patients with segmental dystonia underwent chronic deep brain stimulation (DBS) surgery in the frame of a prospective study protocol. Twelve patients received chronic pallidal stimulation, while 2 patients with prominent dystonic tremor received chronic thalamic ventrointermediate nucleus stimulation. Twelve patients had primary dystonia, and 2 patients secondary dystonia. The Burke-Fahn-Marsden dystonia rating scale (BFM motor) showed a mean relative improvement of 57.3% at the first follow-up (FU1, mean 7 months) and 57.8% at the second follow-up (FU2, mean 16 months). The mean BFM scores were 34.9 +/- 17.7 preoperatively, 14.9 +/- 11.7 at FU1, and 14.8 +/- 10.3 at FU2. Scores of the disability subscale improved by 43% at FU1 and 36% at FU2. Improvement was comparatively less in those patients with secondary dystonia. Dysarthria was a limitation of DBS in 4 patients when using high voltage. Overall, chronic DBS is a very effective treatment option for medically refractory segmental dystonia.