Influence of repetitive transcranial magnetic cortex stimulation on autonomic nervous system function

Repetitive transcranial magnetic stimulation (rTMS) has recently been intro duced as a therapeutic tool in mood and movement disorders. Little is known about the influence of rTMS on the activity of the autonomic nervous syste m. In 10 healthy subjects repetitive magnetic stimulation was performed wit h five 10-Hz pulses over different brain regions (frontal, central, parieto -occipital), cervical nerve roots and in front of the ear (sham stimulation ). We measured the latency and amplitude of the elicited. sympathetic skin response (SSR) and the stimulation-associated heart rate changes. TMS over the nerve roots elicited SSRs with significantly higher amplitudes (0.7 +/- 0.6 mV) than cortex stimulation (0.3 +/- 0.4 mV) or sham stimulation (0.7 +/- 0.1 mV). 20 sec after cortex or nerve root stimulation the heart freque ncy was 3.3-3.6% and after sham stimulation 2.6% higher than the baseline v alue. Cardiac arrhythmias did not occur after rTMS. The results do not indi cate any substantial risk of rTMS in regard to the activation of the autono mic nervous system.