Chronic deep brain stimulation normalizes scalp EEG activity in isolated dystonia.

OBJECTIVE: To investigate cortical activity using scalp EEG in patients with isolated dystonia treated with chronic deep brain stimulation (DBS), on and off stimulation. METHODS: We analyzed 64-channel scalp EEG in 12 isolated dystonia patients treated with chronic DBS (7 generalized, 5 cervical/segmental; 7 globus pallidus (GP), 5 subthalamic nucleus (STN)), and 20 healthy age-matched controls. Recordings during rest and movement task, and clinical motor scores, were collected with DBS-on and during a 90-min DBS washout. RESULTS: Resting state alpha power in the dominant (or contralateral to more dystonic side) motor cortex channel during DBS was comparable to healthy controls, but it increased when DBS was stopped. Resting state and movement-related alpha coherence between bilateral motor cortex channels was increased off DBS. CONCLUSIONS: Chronic DBS reduces exaggerated alpha oscillations and interhemispheric alpha coherence in the motor cortex of patients with isolated dystonia. SIGNIFICANCE: These findings complement related studies in Parkinson's disease and support the view that network desynchronization is a prominent mechanism of DBS in movement disorders.