Skin biopsy as an aid to diagnosis of disorders of the nervous system without cutaneous manifestations

There are several neurological diseases wherein skin biopsy is useful for diagnosis, even in the absence of skin involvement. Skin biopsy is especially relevant in diseases in which the metabolic error is unknown or has no available diagnostic biochemical test. Skin biopsy, being relatively noninvasive, obviates the need for an invasive procedure such as a brain biopsy. These disorders wherein skin biopsies are particularly useful include the progressive myoclonic epilepsies, cerebral autosomal dominant arteriopathy with subcortical infarcts and leukoencephalopathy (CADASIL), neuroaxonal dystrophy, and small fiber neuropathies (SFN). We review the role of skin biopsy in such conditions with notes on preferred sites and techniques.