Sympathetic skin response: review of the method and its clinical use

Sympathetic skin response (SSR) represents a potential generated in skin sweat glands; it originates by activation of the reflex arch with different kinds of stimuli. The potential of rapid habituation after repeated stimuli is formed by biphasic or triphasic slow wave activity with relatively stable latency and variable amplitude. In healthy subjects younger than 60 years of age the response is always present in all extremities. SSR is most frequently used in diagnosing the functional impairment of non-myelinated postganglionic sudomotor sympathetic fibers in peripheral neuropathies. In this study a more complex and informative view on the anatomical and physiological substrates of SSR, its character, normal values and technique are presented, focusing on problems in evaluation of the response and factors that have influence on it. Based on personal experience normative latency and amplitude values of SSR in a group of 20 healthy individuals (x +/- SD), upper extremities: 1.48 +/- 0.80 sec., 444 +/- 167 microV, respectively; lower extremities: 2.06 +/- 0.93 sec., 203 +/- 87.4 microV, respectively) and recommendations for qualitative evaluation preference--the presence or absence of the response--over quantitative evaluation of latency and amplitude of the response in practical clinical use of the method are presented. (Tab. 1, Fig. 2, Ref. 148.).