Low-frequency repetitive transcranial magnetic stimulation for treatment of levodopa-induced dyskinesias

Abstract

Levodopa-induced dyskinesia (LID) is a major source of disability in Parkinson disease (PD) and functional imaging studies suggest that it may be related to overactivity of the motor cortex.1 Low- frequency repetitive transcranial magnetic stimulation (rTMS) at about 1 Hz decreases excitability of the stimulated area.2 A single 15-minute session of 1 Hz rTMS to the supplementary motor area reduced LID for up to 15 minutes.3 We hypothesize that longer sessions4 such as a 2-week course of 1 Hz rTMS to primary motor cortex will produce longer lasting reduction of LID. We studied six patients with PD (table E-1 on the Neurology Web site at www.neurology.org). Inclusion criteria were 1) stable medication dose for 4 weeks, and 2) LID >25% of waking hours (item 32 of Unified PD Rating Scale [UPDRS] ≥ 2) and bothersome (item 33 ≥ 2). Exclusion criteria were previous PD surgery and contraindications to rTMS. Patients took regular medications during the study except on days of levodopa challenge test. Informed consent and Ethics Board approval were obtained. Patients received 10 days of …