Sudo Scan is a medical device that has been cleared by the FDA for Neuropathy. It is a galvanic skin response (GSR) test. A GSR test measures changes in the electrical properties of the skin in response to different kinds of stimuli. In GSR, changes in the voltage measured from the surface of the skin are recorded. The main origin of the signal has been suggested to be the activation of sweat glands (sudomotor function).
“Sweat response may be the most sensitive test in detecting distal small fiber neuropathy.” (See publications by Low et al. and Gibbons et al). Eccrine glands that are responsible for sweat response receive a rich supply of blood vessels and are innervated by sympathetic C nerve fibers (autonomic nervous system). These fibers are thin and long, and so can be impaired at the early stage of different metabolic diseases, such as diabetes. Testing sudomotor function can be a fast and accurate method for detecting early stages of neuropathies.