Repetitive transcranial magnetic stimulation to SMA worsens complex movements in Parkinson's disease

Objectives: To evaluate the therapeutic potential of repetitive transcrania l magnetic stimulation (rTMS) for Parkinson's disease (PD) by delivering st imulation at higher intensity and frequency over longer time than in previo us research. Promising beneficial effects on movement during or after rTMS have been reported. Methods: Ten patients with idiopathic PD were enrolled in a randomized cros sover study comparing active versus sham rTMS to the supplementary motor ar ea (SMA). Assessments included reaction and movement times (RT/MT), quantit ative spiral analysis. timed motor performance tests, United Parkinson's Di sease Rating Scale (UPDRS), patient self-report and guess as to stimulation condition. Results: Two of 10 patients could not tolerate the protocol. Thirty to 45 m in following stimulation, active rTMS as compared with sham stimulation wor sened spiral drawing (P = 0.001) and prolonged RT in the most affected limb (P = 0.030). No other significant differences were detected. Conclusions: We sought clinically promising improvement in PD but found sub clinical worsening of complex and preparatory movement following rTMS to SM A. These results raise safety concerns regarding the persistence of dysfunc tion induced by rTMS while supporting the value of rTMS as a research tool. Studies aimed at understanding basic mechanisms and timing of rTMS effects are needed. (C) 2001 Elsevier Science Ireland Ltd. All rights reserved.