Bilateral deep-brain stimulation of the globus pallidus in primary generalized dystonia.
BACKGROUND: Severe forms of dystonia respond poorly to medical treatment. Deep-brain stimulation is a reversible neurosurgical procedure that has been used for the treatment of dystonia, but assessment of its efficacy has been limited to open studies. METHODS: We performed a prospective, controlled, multicenter study assessing the efficacy and safety of bilateral pallidal stimulation in 22 patients with primary generalized dystonia. The severity of dystonia was evaluated before surgery and 3, 6, and 12 months postoperatively during neurostimulation, with the use of the movement and disability subscores of the Burke-Fahn-Marsden Dystonia Scale (range, 0 to 120 and 0 to 30, respectively, with higher scores indicating greater impairment). Movement scores were assessed by a review of videotaped sessions performed by an observer who was unaware of treatment status. At three months, patients underwent a double-blind evaluation in the presence and absence of neurostimulation. We also assessed the patients' quality of life, cognition, and mood at baseline and 12 months. RESULTS: The dystonia movement score improved from a mean (+/-SD) of 46.3+/-21.3 before surgery to 21.0+/-14.1 at 12 months (P<0.001). The disability score improved from 11.6+/-5.5 before surgery to 6.5+/-4.9 at 12 months (P<0.001). General health and physical functioning were significantly improved at month 12; there were no significant changes in measures of mood and cognition. At the three-month evaluation, dystonia movement scores were significantly better with neurostimulation than without neurostimulation (24.6+/-17.7 vs. 34.6+/-12.3, P<0.001). There were five adverse events (in three patients); all resolved without permanent sequelae. CONCLUSIONS: These findings support the efficacy and safety of the use of bilateral stimulation of the internal globus pallidus in selected patients with primary generalized dystonia.