Pallidal Deep-Brain Stimulation in Primary Generalized or Segmental Dystonia

Abstract

Neurostimulation of the internal globus pallidus has been shown to be effective in reducing symptoms of primary dystonia. We compared this surgical treatment with sham stimulation in a randomized, controlled clinical trial. Forty patients with primary segmental or generalized dystonia received an implanted device for deep-brain stimulation and were randomly assigned to receive either neurostimulation or sham stimulation for 3 months. The primary end point was the change from baseline to 3 months in the severity of symptoms, according to the movement subscore on the Burke-Fahn-Marsden Dystonia Rating Scale (range, 0 to 120, with higher scores indicating greater impairment). Two investigators who were unaware of treatment status assessed the severity of dystonia by reviewing videotaped sessions. Subsequently, all patients received open-label neurostimulation; blinded assessment was repeated after 6 months of active treatment. Three months after randomization, the change from baseline in the mean (+/-SD) movement score was significantly greater in the neurostimulation group (-15.8+/-14.1 points) than in the sham-stimulation group (-1.4+/-3.8 points, P<0.001). During the open-label extension period, this improvement was sustained among patients originally assigned to the neurostimulation group, and patients in the sham-stimulation group had a similar benefit when they switched to active treatment. The combined analysis of the entire cohort after 6 months of neurostimulation revealed substantial improvement in all movement symptoms (except speech and swallowing), the level of disability, and quality of life, as compared with baseline scores. A total of 22 adverse events occurred in 19 patients, including 4 infections at the stimulator site and 1 lead dislodgment. The most frequent adverse event was dysarthria. Bilateral pallidal neurostimulation for 3 months was more effective than sham stimulation in patients with primary generalized or segmental dystonia. (ClinicalTrials.gov number, NCT00142259 [ClinicalTrials.gov].).