Electrophysiological and Neuroimaging Correlates of the Effect of Zolpidem in Patients With Focal Dystonia

To study electrophysiological and imaging correlations of the clinical effectiveness of zolpidem in task-specific dystonia and to elucidate mechanisms underlying its therapeutic effects, patients with focal dystonia will be clinically evaluated and will undergo transcranial magnetic stimulation and FDG-PET CT brain imaging after a single 5 mg dose of zolpidem and placebo, in two separate sessions. Resting motor threshold (RMT), active motor threshold (AMT), resting and active input/output (IO) curve, short-interval intracortical inhibition (SICI) curve, long interval intracortical inhibition (LICI), intracortical facilitation (ICF), and cortical silent period (CSP) will be measured. Objective clinical improvement will be rated using Burke-Fahn-Marsden Dystonia Rating Scale-movement (BFM-M) and writer's cramp rating scale (WCRS). Subjective improvement will be measured using the visual analog scale (VAS). Only a subset of patients (10 patients) will undergo positron emission tomography with 18F-2-fluoro-2-deoxy-D-glucose (18F-FDG PET) brain imaging after a single 5 mg dose of zolpidem and placebo.