Bilateral, pallidal, deep-brain stimulation in primary generalised dystonia: a prospective 3 year follow-up study.

Background: We have previously reported the efficacy and safety of bilateral pallidal stimulation for primary generalised dystonia in a prospective, controlled, multicentre study with 1 year of follow-up. Although long-term results have been reported by other groups, no controlled assessment of motor and non-motor results is available. In this prospective multicentre 3 year follow-up study, involving the same patients as those enrolled in the 1 year follow-up study, we assessed the effect of bilateral pallidal stimulation on motor impairment, disability, quality of life, cognitive performance, and mood.
Methods: We studied 22 patients with primary generalised dystonia after 3 years of bilateral pallidal stimulation. We compared outcome at 3 years with their status preoperatively and after 1 year of treatment. Standardised video recordings were scored by an independent expert. Data were analysed on an intention-to-treat basis.
Findings: Motor improvement observed at 1 year (51%) was maintained at 3 years (58%). The improvement in quality of life (SF-36 questionnaire) was similar to that observed at 1 year. Relative to baseline and to the 1 year assessment, cognition and mood were unchanged 3 years after surgery, but slight improvements were noted in concept formation, reasoning, and executive functions. Pallidal stimulation was stopped bilaterally in three patients because of lack of improvement, technical dysfunction, and infection, and unilaterally in two patients because of electrode breakage and stimulation-induced contracture. No permanent adverse effects were observed.
Interpretation: Bilateral pallidal stimulation provides sustained motor benefit after 3 years. Mild long-term improvements in quality of life and attention were also observed.