Inclusion Criteria:  patients 18-85 years of age who receive regular botulinum toxin (BoNT) scheduled every 12 weeks, on stable optimized doses but with reported benefits lasting ≤ 9 weeks for 2 consecutive cycles. Patents followed at our center routinely fill out a self-reported form to document the duration of benefits perceived with BoNT therapy. Participants will be allowed to continue oral medications that they are taking for dystonia concurrently but will not be allowed to change their concurrent medication regimen throughout the duration of the study.  Exclusion Criteria:  Presence of metallic objects or neurostimulators in the brain Pregnancy History of active seizures or epilepsy Patients with severe scoliosis or other gait impairment that will preclude them from participating in gait evaluation.