Long-Term Outcome of Subthalamic Deep Brain Stimulation for Generalized Isolated Dystonia.

OBJECTIVES:Few studies have focused on subthalamic nucleus deep brain stimulation for refractory isolated dystonia, and the long-term outcomes are unclear. In this study, we evaluated the efficacy of subthalamic stimulation for generalized isolated dystonia for more than five years and explored the factors predicting clinical outcomes. MATERIALS AND METHODS:A total of 16 patients with generalized isolated dystonia underwent a two-phase procedure for stimulation system implantation. After implanting the leads, we performed a test stimulation and observed the stimulation response. The severity of dystonia was assessed using a blinded rating of the Burke-Fahn-Marsden Dystonia Rating Scale based on videos recorded at scheduled times. RESULTS:The mean follow-up time was 7.4 ± 2.2 years (5-12.5 years). The severity of dystonia improved significantly one year after surgery. The movement score decreased from 49.3 (40.9) points at baseline to 26.5 (43.5) points (-44.6%) at six months, 12.0 (22.5) points (-66.8%) at one year, 11.25 (17.6) points (-72.7%) at three years, and 12.5 (21.0) points (-72.6%) at the last follow-up. The improvement in motor symptoms resulted in a corresponding improvement in activities of daily living. Greater long-term outcomes were correlated with early stimulation responses, lower baseline movement scores, and female sex. When analyzed comprehensively, only the baseline movement score had meaningful predictive value for the outcome. CONCLUSIONS:Our results indicate that subthalamic stimulation is effective and durable in treating generalized isolated dystonia. The subthalamic nucleus may be an alternative target for the treatment of refractory dystonia. Patients with less severe motor symptoms may benefit more from this treatment.