Stroke Research Today is a free monthly online journal that collates and summarizes the latest research about Stroke, including details on treatment, recovery, rehabilitation, signs, symptoms.

Safety study of high-frequency transcranial magnetic stimulation in patients with chronic stroke.

Lomarev MP, Kim DY, Richardson SP, Voller B, Hallett M

Human Motor Control Section, National Institute of Neurological Disorders and Stroke, National Institutes of Health, NIH Building 10, Room 5N240, 10 Center Dr MSC 1428, Bethesda, MD 20892-1428, USA. lomarevm@ninds.nih.gov

OBJECTIVE: Repetitive transcranial magnetic stimulation (rTMS) is a potential therapeutic tool to rehabilitate chronic stroke patients. In this study, the safety of high-frequency rTMS in stroke was investigated (Phase I). METHODS: The safety of 20 and 25 Hz rTMS over the motor cortex (MC) of the affected hemisphere, with intensities of 110-130% of the motor threshold (MT), was evaluated using surface electromyography (EMG) of hand and arm muscles. RESULTS: Brief EMG bursts, possibly representing peripheral manifestations of after discharges, and spread of excitation to proximal muscles are considered to be associated with a high risk of seizure occurrence. These events were recorded after the rTMS trains. Neither increased MC excitability nor improved pinch force dynamometry was found after rTMS. CONCLUSIONS: Stimulation parameters for rTMS, which are safe for healthy volunteers, may lead to a higher risk for seizure occurrence in chronic stroke patients. SIGNIFICANCE: rTMS at rates of 20 and 25 Hz using above threshold stimulation potentially increases the risk of seizures in patients with chronic stroke.

Published 7 August 2007 in Clin Neurophysiol, 118(9): 2072-5.
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