Bilateral deep brain stimulation of the pallidum for myoclonus-dystonia due to ε-sarcoglycan mutations: a pilot study.

Objective: To assess the efficacy of bilateral deep brain stimulation of the internal pallidum in patients with myoclonus-dystonia due to genetically proved ε-sarcoglycan (SGCE-M-D) deficiency.

Design: Patients with documented SGCE-M-D undergoing bilateral deep brain stimulation of the internal pallidum were recruited. Standardized assessments of M-D were videorecorded before surgery and 6 to 9 months and 15 to 18 months after surgery, using the movement and disability subscales of the Burke-Fahn-Marsden Dystonia Rating Scale and the Unified Myoclonus Rating Scale. The analysis was based on blinded evaluation of the recordings.

Setting: Movement disorder unit in a university hospital in Paris.

Patients: Five consecutive patients with documented SGCE-M-D.

Main Outcome Measures: Myoclonus and dystonia scores at follow-up.

Results: The median myoclonus score decreased from 76 before surgery (range, 38-116) to 10 at 6 to 9 months after surgery (range, 6-31). The median dystonia score decreased from 30.0 before surgery (range, 18.5-53.0) to 4.5 after surgery (range, 3.5-16.0). Disability was also improved and symptoms remained stable between the postoperative evaluations. No adverse effects occurred.

Conclusions: Bilateral deep brain stimulation of the internal pallidum is safe and highly effective in this homogeneous population of patients with SGCE-M-D. This therapeutic option should therefore be considered for patients with severe, drug-resistant forms of the disorder.