Training effects outweigh effects of single-session conventional rTMS and theta burst stimulation in PD patients

Abstract

Background. Focal single-session repetitive transcranial magnetic stimulation (rTMS) of the primary motor cortex has been claimed to be capable of improving motor function in Parkinson's disease. Objective. The authors sought to determine which type of rTMS protocol holds the highest potential for future therapeutic application. Methods. Twenty-two patients with Parkinson's disease received 5 different rTMS protocols on 5 consecutive days in a pseudorandomized and counterbalanced order either in the defined OFF condition or with their usual medication. The protocols tested in the present study included 2 conventional rTMS protocols (0.5 and 10 Hz) as well as the recently introduced theta burst stimulation (cTBS, iTBS) and a sham condition. Cortical excitability, motor performance (pointing movement, pronation-supination, Purdue Pegboard Test, walking), and mood were assessed before and after each session. Results. The authors observed motor training from days 1 to 4, particularly in the group on dopaminergic medication. None of the rTMS paradigms excelled placebo stimulation. The only exception was the Purdue Pegboard Test, in which all active stimulation paradigms yielded slightly stronger effects than sham stimulation. Conclusions. Within a single session, no clinically relevant difference in the rTMS protocols could be detected. Training effects outweigh and may have masked rTMS effects, particularly in the group on dopaminergic mediation.