Sympathetic skin response (SSR)]

The sympathetic skin response (SSR) is a slow wave resulting from activation of the sudomotor sympathetic efferent fibers. Records are usually made with surface electrodes on hand or foot after the electrical stimulation. Either the amplitude or the latency of the response varies greatly on consecutive stimulations and there is also a remarkable tendency to habituation. Therefore SSR is considered abnormal if no significant responses are detected. SSR is well correlated with other autonomic function tests and its abnormality is documented in a variety of neurologic disorders such as diabetic neuropathy, cerebrovascular disease and Parkinson's disease. In good methodological conditions, SSR is a simple, reliable indicator of sympathetic sudomotor outflow in central and peripheral nervous system disorders.