Sixty hertz pallidal deep brain stimulation for primary torsion dystonia

Objective: To evaluate the safety and efficacy of 60 Hz deep brain stimulation (DBS) of the globus pallidus internus (GPi) in 15 consecutive patients with primary dystonia. Methods: We conducted a retrospective analysis of clinic charts relative to 15 consecutive patients with medically refractory primary dystonia who underwent stereotactic implantation of DBS leads within the GPi. Twelve had the DYT1 gene mutation. Frame-based MRI and intraoperative microelectrode recording were employed for targeting. All patients were treated exclusively with stimulation at 60 Hz from therapy outset. The Burke-Fahn-Marsden Dystonia Rating Scale (BFMDRS) served as the primary measure of symptom severity at baseline and 1, 3, 6, and 12 months after treatment. Results: All patients tolerated DBS treatment well and showed a progressive median improvement of their BFMDRS motor subscores from 38% at 1 month to 89% at 1 year (p < 0.001, Wilcoxon rank sum test). The disability subscores were similarly improved. The clinical response to DBS allowed seven patients to completely discontinue their medications; six additional patients had reduced their medications by at least 50%. Surgical complications were limited to two superficial infections, which were treated successfully. Conclusions: Stimulation of the internal globus pallidus at 60 Hz is safe and effective for treating medically refractory primary dystonia.