Fifteen-Year Outcomes of Bilateral Pallidal Stimulation in Isolated Generalized Dystonia: Characterization of Therapeutic Response and Emergence of Parkinsonism.
Abstract
Background
Bilateral pallidal deep brain stimulation (GPi-DBS) is effective for dystonia. Long-term evolution of therapeutic benefit and emergence of parkinsonism have not been systematically characterized.
Objectives
To assess 15-year dystonia outcomes and characterize parkinsonism after bilateral GPi-DBS.
Methods
Dystonia severity and disability were evaluated at baseline,1, 3, and 15 years postoperatively with the Burke-Fahn-Marsden Dystonia Rating Scale (BFMDRS). Parkinsonism was assessed at last visit using the Movement Disorder Society-Unified Parkinson's Disease Rating Scale-Part III and freezing of gait (FoG) questionnaire.
Results
Of 17 patients reassessed at 15 years, 41% maintained clinical benefit. Parkinsonism was observed in 94%, predominantly axial, with self-reported FoG in 67%. Higher baseline BFMDRS-Motor scores predicted last follow-up axial parkinsonism (R = 0.800, P < 0.001).
Conclusions
Over 15 years, interindividual therapeutic benefit diverged while axial parkinsonism emerged in nearly all patients. These findings highlight the need for systematic long-term monitoring extending beyond dystonia control after GPi-DBS. © 2026 The Author(s). Movement Disorders published by Wiley Periodicals LLC on behalf of International Parkinson and Movement Disorder Society.