Interruption of deep brain stimulation of the globus pallidus in primary generalized dystonia

Stimulation (DBS) of the globus pallidus (GP) is effective to treat generalized dystonia. Little is known about the evolution of dystonia in case of arrest after a long period of stimulation. This study describes the course of dystonia during a 48 hours period without stimulation followed by a 24 hours period after turning ON the stimulator. 14 patients with generalized dystonia treated with bilateral GP DBS for 3 years or more were recruited. Blinded video-based analysis was performed using Burke-Fahn-Marsden scale at (1) baseline (ON stimulation), (2) up to 48 hours after the stimulator was turned OFF, and (3) 24 hours after the stimulator was turned ON. 13 patients completed the 48 hours OFF-stimulation period. The dystonia movement score progressively worsened from 24.3 +/- 13.9 at baseline to 48.9 +/- 19.8 after 48 hours (P < 0.00001). The disability score also worsened from 4.4 +/- 1.2 at baseline to 5.7 +/- 1.5 after 48 hours without stimulation (P < 0.001). When the neurostimulator was turned ON, the dystonia scores returned to baseline level after 10 hours. The interruption of GP DBS in dystonia results in a progressive worsening which is rapidly reversible once the neurostimulator is turned ON.