[Neuropathy and unmyelinated epidermal nerve fibers].

Detection of unmyelinated epidermal nerve fibers allows objective, pathologic, and minimally invasive assessment of small myelinated A-delta and unmyelinated C primary afferent fibers. This procedure is especially valuable for diagnosing small fiber neuropathy; this condition is characterized by sensory symptoms and pain in the lower extremities but standard nerve conduction fails to show abnormalities in this condition. Detection of epidermal nerve fibers is useful not only for confirming the diagnosis of neuropathies affecting small-diameter sensory fibers, but also in advanced clinical care since this procedure can provide insights into the role of small myelinated and unmyelinated axons in peripheral nerve disorders and neuropathic pain. In this review, we discuss standard technical aspects of skin biopsy introduced for evaluation of epidermal nerve fibers and the feasibility of skin biopsy for diagnosing small fiber neuropathy and neuronopathy. We also describe the usefulness of skin biopsy in diagnosing peripheral neuropathies and other neurological disorders.