Abolition of sympathetic skin responses following endoscopic thoracic sympathectomy.

The recording of sympathetic skin responses (SSRs) is a simple, electrophysiological method to assess sympathetic nerve function. Within the last 10 years, SSRs have mainly been applied to delineate peripheral and central nervous system diseases, although the sympathetic nature of these responses was not fully documented, e.g., by a study of sympathectomy. We therefore recorded SSRs before and after 30 cases of endoscopic thoracic sympathectomy. The main indication was palmar hyperhidrosis, in which we found two types of SSR abnormalities. Most patients exhibited normal SSR waveforms but with increased amplitudes. The other patients exhibited abnormal SSRs which did not occur as single responses but as several consecutive waves. Thoracic sympathectomy always led to significant clinical improvement and to the abolition of ipsilateral palmar SSRs, demonstrating the sympathetic origin of these responses. We suggest that the assessment of sympathetic nerve activity by SSR recordings may be useful in sympathectomy.