Small fiber neuropathy is a condition that can cause numbness, tingling or burning.
Small fiber nerves are thin, unmyelinated nerves in the surface of the skin. They may also be found in the tissue surrounding organs. They may carry sensation to touch, temperature, or regulate sweating. Large fibers are nerves that carry sensation and motor functions, and can be tested for by nerve conduction studies (EMG). Small fiber neuropathy may be diagnosed by a microscope exam of the fibers in a skin biopsy. Small fiber neuropathy is sometimes diagnosed by quantitative autonomic testing. These tests are not widely available, although sometimes a biopsy sample can be sent to a testing center.
The most common cause of small fiber neuropathy is hyperglycemia (such as that in diabetes mellitus). Other causes include thyroid disease, connective tissue or autoimmune disorders, infection, exposure to toxins and medication side effects.
As with other kinds of neuropathy, treatment of the condition depends on the cause and the need to control the symptoms. Many small fiber neuropathy cases have no apparent cause.