Safety

Single-pulse TMS and low frequency rTMS (<1Hz) in healthy adults appears to carry little risk beyond occasionally causing local discomfort at the site of stimulation, or a transient headache in susceptible subjects. Safety studies found no short- or long-term sequelae after with single pulse TMS and low frequency rTMS in presumed normal adults [1]. Similarly, no ill effects have been reported after magnetic stimulation of the peripheral nervous system and, after cortical stimulation, the incidence of side effects has been extremely low and well within that expected from statistics for various patient groups [2].

High frequency, high-intensity repetitive TMS (rTMS) has some risk of inducing seizures, even in normal people [1, 3]. After ten years that research with TMS started (1985), seven accidental cases of seizure were documented. For this reason, in 1996, a workshop was held to review information on the safety of rTMS and to develop guidelines for its safe use; the summary, published in 1998[3], contained detailed descriptions of all possible rTMS risks and safe conservative guidelines to minimize them . Since then, the rTMS risks have fallen considerably.

Some TMS devices received FDA approval for peripheral-nerve stimulation; however, cortical stimulation still is investigational. Studies with TMS are classified in two groups: a) non-significant risk (NSR), and, b) significant risk (SR). NSR may only require IRB-approved protocol and consent; however, SR studies require in addition an FDA approval. (See FDA-NSR/SR)

1. Anand S and Hotson J, Transcranial magnetic stimulation: neurophysiological applications and safety. Brain Cogn, 2002. 50: 366-86.
2. Kandler R, Safety of transcranial magnetic stimulation. Lancet, 1990. 335: 469-70.
3. Wassermann E M, Risk and safety of repetitive transcranial magnetic stimulation: report and suggested guidelines from the International Workshop on the Safety of Repetitive Transcranial Magnetic Stimulation, June 5-7, 1996. Electroencephalogr Clin Neurophysiol., 1998. 108: 1-16.

Last Modified: February 1, 2008
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