Acute Deep-Brain Stimulation of the Internal and External Globus Pallidus in Primary Dystonia

trapallidal localization of the contacts of the quadripolar electrodes was performed using a 3-dimensional atlas–magneticresonanceimagingcoregistrationmethod by investigators blinded to the clinical outcome. Results:BilateralacuteventralstimulationoftheGPsignificantly improved the Burke-Fahn-Marsden Dystonia Rating Scale score by 42% and resulted in stimulation of contacts located in the internal GP or medullary lamina in 18 of 21 patients. Bilateral acute dorsal pallidal stimulation, primarily localized within the external GP, had variable effects across patients, with half demonstrating slight or no improvement or even aggravation of dystonia compared with baseline. Conclusions: Ventral pallidal stimulation, primarily of the internal GP or medullary lamina or both, is the optimal method for the treatment of dystonia. The varying effects across patients of bilateral acute dorsal pallidal stimulation, primarily of the external GP, suggest that unknown factors associated with dystonia could have a role in and contribute to the effects of the electrical stimulation.