Long-Term Outcome of Idiopathic and Acquired Dystonia After Pallidal Deep Brain Stimulation: A Case Series

BACKGROUND Among dystonia patients receiving globus pallidus internus (GPi) deep brain stimulation (DBS), long-term outcomes remain to be established. OBJECTIVE To report the long-term outcome of GPi DBS in a patient cohort with idiopathic and acquired dystonia. METHODS In this long-term follow-up cohort, there were 4 patients with idiopathic dystonia and 2 patients with acquired dystonia. The Burk-Fahn-Marsden Dystonia Rating Scale (BFMDRS) was used to evaluate 6 consecutive patients preoperatively and at 6 months, 12 months, and the last follow-up. The relationship between etiology and clinical improvement was analyzed. Stimulation parameters were evaluated for similarities and differences among these patients. RESULTS The mean follow-up of our cohort was 65.3 months (median 40.5 months). The average improvement in BFMDRS (mean ± SEM) was 56% ± 7.6, 67% ± 6.8 and 66% ± 9.7 at 6 months, 12 months, and last follow-up, respectively. There was greater improvement during long-term follow-up in the 4 patients with idiopathic dystonia than in the 2 patients with acquired dystonia. The 2 most ventral electrodes (contact 0 and 1) were activated in all 11 leads in this cohort. The average stimulation intensity, pulse width and frequency were 2.0 ± 0.24 mA, 252 ± 43 µs, and 99 ± 6.0 Hz, respectively. CONCLUSION Isolated dystonia, either monogenetic or idiopathic, usually responds better to GPi DBS than does acquired dystonia. Selection of patients by dystonia etiology, accurate placement of DBS leads in GPi targets, and proper stimulation programming are crucial to achieve better long-term outcomes.