Abnormal peripheral nervous system morphology Reduced intraepidermal small nerve fiber density 2023-07-19T11:40:04Z Reduced number of small nerve fibers in the skin. Small fibers travel too slowly, and their conduction responses cannot be captured by a nerve conduction study, which is a routine test performed to evaluate large sensory and motor nerve fibers. Therefore, a skin biopsy is often used to assess small sensory nerve fibers in the skin. Skin biopsy is a minimally invasive procedure that may also be used to evaluate intraepidermal nerve fiber density. Skin specimens are typically obtained by a 3 mm punch biopsy at the distal leg and thigh and are then sent for laboratory analysis. Small fiber neuropathy may be diagnosed if the intraepidermal nerve fiber density is less than normal.