Sympathetic skin responses of the face and neck evoked by electrical stimulation

The sympathetic skin responses (SSRs) were recorded from different facial regions and neck in 25 subjects evoked by electrical stimulation of the median nerve at the wrist. Recordings from all regions were cross-compared with each other and within right and left sides individually. In one subject postauricular SSR, and in another subject upper lip SSR could not be elicited on both sides. Other responses could be obtained in all the remaining subjects. In 11 subjects, the responses did not appear by the first stimulus, and began to appear by repeated stimuli. Mean latencies and the highest amplitudes of the responses were similar for both sides. Gradual amplitude increase was observed in the first three or four set of responses in 20 subjects, although the stimulus intensity was constant. In conclusion, face and neck SSRs are symmetric, can be evoked by electrical stimulation and can be used to investigate the sympathetic innervation of these areas.