Long-term effects of pallidal deep brain stimulation in tardive dystonia

High-frequency stimulation of the globus pallidus internus (GPi) is a highly effective therapy in primary dystonia. Recent reports have also demonstrated almost immediate improvement of motor symptoms in patients with tardive dystonia after pallidal deep brain stimulation (DBS). Here, we show the long-term effect of continuous bilateral GPi DBS in tardive dystonia on motor function, quality of life (QoL), and mood.

Nine consecutive patients undergoing DBS for tardive dystonia were assessed during continuous DBS at 3 time points: 1 week, 3 to 6 months, and last follow-up at the mean of 41 (range 18-80) months after surgery using established and validated movement disorder and neuropsychological scales. Clinical assessment was performed by a neurologist not blinded to the stimulation settings.

One week and 3 to 6 months after pallidal DBS, Burke-Fahn-Marsden Dystonia Rating Scale (BFMDRS) motor scores were ameliorated by 56.4 +/- 26.7% and 74.1 +/- 15.8%, BFMDRS disability scores by 62.5 +/- 21.0% and 88.9 +/- 10.3%, and Abnormal Involuntary Movement Scale (AIMS) scores by 52.3 +/- 24.1% and 69.5 +/- 27.6%, respectively. At last follow-up, this improvement compared with the presurgical assessment was maintained as reflected by a reduction of BFMDRS motor scores by 83.0 +/- 12.2%, BFMDRS disability scores by 67.7 +/- 28.0%, and AIMS scores by 78.7 +/- 19.9%. QoL improved significantly in physical components, and there was a significant improvement in affective state. Furthermore, cognitive functions remained unchanged compared with presurgical status in the long-term follow-up. No permanent adverse effects were observed.

Pallidal deep brain stimulation is a safe and effective long-term treatment in patients with medically refractory tardive dystonia.