Sudomotor function is controlled by a division of the sympathetic system relating to nerve fibers controlling the activity of sweat glands (post sympathetic cholinergic fiber or C-fibers). Sudomotor dysfunction is using to define a decreased sudomotor activity.

Sudomotor function evaluation is primarily employed to detect skin blood flow (microcirculation) and C-fiber density for early detection (first stages) of peripheral distal neuropathy in populations at high risk of diseases such as Type II Diabetes.

Sudomotor dysfunction is one of the earliest detectable neurophysiologic abnormalities in distal small fiber neuropathy. Traditional neurophysiologic measurements of sudomotor function include thermoregulatory sweat testing (TST), quantitative sudomotor axon reflex testing (QSART), silicone impressions, the sympathetic skin response (SSR), and the recent addition of quantitative direct and indirect axon reflex testing (QDIRT). These testing techniques, when used in combination, can detect and localize pre- and post- ganglionic lesions, provide early diagnosis of sudomotor dysfunction, and monitor disease progression or disease recovery. 

Sudomotor Function