SYMPATHETIC SKIN-RESPONSE - A DECADE LATER

Sympathetic skin response (SSR) is a simple, reproducible test of func tion of a polysynaptic reflex having diverse afferents, a common effer ent pathway through the spinal cord, pre and post-ganglionic sympathet ic fibers and with sweat glands as effecters. The reflex is co-ordinat ed in the posterior hypothalamus or upper brainstem reticular formatio n. It has been used in a variety of disorders of peripheral and centra l nervous system. Methodology, possible anatomic substrates, changes i n SSR in various diseases and their correlation with clinical features of dysautonomia, bed side tests for dysautonomia and other electrophy siological parameters are critically evaluated. Almost a decade after the start of its widespread clinical utilization, several aspects of S SR remain inconclusive. A consensus as to what change in SSR to consid er abnormal is yet to be reached. Though its ease of application super sedes a variety of other autonomic function tests, relying only on SSR changes for prognostication or therapeutic decisions appears impracti cable. A battery of tests is thus a necessity.