MAGNETIC STIMULATION OVER DIFFERENT BRAIN-REGIONS - NO DIFFERENTIAL-EFFECTS ON THE ELICITED SYMPATHETIC SKIN-RESPONSES

Peak latencies and amplitudes of sympathetic skin responses (SSRs) of the hand following magnetic stimulation at different sites with two or five consecutive 10-Hz stimuli were investigated with regard to safet y aspects of repetitive transcranial magnetic cortex stimulation (rTMS ). The amount of sympathetic activation as assessed by the amplitudes of the SSRs depended on the stimulation site and decreased in the foll owing order: brachial plexus stimulation > nerve root stimulation > st imulation over the brain > activation by acoustic coil artefact. When stimulating over six different regions of the cortex (frontal, central , parieto-occipital, and both hemispheres), the elicited SSRs had simi lar amplitudes and peak latencies. The SSRs elicited by rTMS over the motor cortex were not related to the sum of the amplitudes of excitato ry muscle compound responses. Currents with opposite directions over t he motor cortex markedly influenced the size of the motor responses bu t not of the SSRs. The number of consecutive 10-Hz stimuli did not inf luence the latencies or amplitudes of the SSRs. It can be concluded th at SSRs after magnetic stimulation over peripheral nerves or the brain are a correlate of an unspecific arousal reaction. A therapeutic appl ication of short series of rTMS should not be limited by the amount of sympathetic activation. (C) 1998 Elsevier Science Ireland Ltd.