What is small fiber peripheral neuropathy?
Small fiber peripheral neuropathy (SFPN) is a type of peripheral neuropathy due to damage of small, unmyelinated C fibers and thinly myelinated A-delta fibers that innervate the skin or autonomic system. It can present with paresthesias, dysesthesias, pain, or numbness. Other symptoms include changes in skin color and temperature, sweating, or the presence of edema. Most commonly symptoms and signs are length-dependent, starting in the distal portion of longer nerves. There are many causes of small fiber neuropathy from diabetes (the most common) to nutritional deficiencies and infectious causes such as Lyme disease, many of which will be described later. Because large fibers are spared, routine electrodiagnostic studies do not confirm the presence of SFPN.