Nerve and skin biopsy in neuropathies.

PURPOSE OF REVIEW: To give an overview of recent data on the use of nerve and skin biopsy as a diagnostic tool in neuropathies.

RECENT FINDINGS: Axonal damage in a biopsy from a patient with chronic inflammatory demyelinating polyradiculoneuropathy may point to the presence of autoantibodies to paranodal proteins. In nonsystemic vasculitis of the peripheral nervous system, nerve biopsy is still the only means to make a definite diagnosis. Increased autophagy has been found in idiopathic neuropathy and may also be a common final pathway in various types of neuropathy. Nerve biopsy has unexpectedly revealed familial amyloid neuropathy in a number of cases that were taken for idiopathic, for Charcot-Marie-Tooth disease, or for chronic inflammatory demyelinating polyradiculoneuropathy. Skin biopsy can differentiate between length-dependent and non-length-dependent small fiber neuropathy, which aids in the etiological differential diagnosis. It can also be used to identify small fiber involvement in mixed neuropathies and for follow-up studies.

SUMMARY: Nerve biopsy is still the gold standard for the diagnosis of peripheral nerve vasculitis. In other indications, sural or superficial peroneal nerve biopsies are less frequently done, because less invasive methods have become available. Modern imaging methods allow localization of nerve damage, such that targeted fascicular biopsies can be done. Immunofluorescence staining of teased nerve fibers has contributed to the understanding of the pathophysiology of inflammatory neuropathies. Skin biopsy has become a routine method to diagnose small fiber neuropathy.