Peripheral neuropathy : from pathology to treatment

Abstract

Peripheral neuropathy is caused by a variety of diseases. Early diagnosis and initiation of treatment is important because irreversible damage may occur. Although careful assessment of the mode of progression, symptoms and signs, blood and cerebrospinal fluid examinations, and electrophysiological studies may lead to diagnosis, nerve biopsy is also useful to determine the underlying diseases in some of the patients with neuropathy. Sural nerve is usually taken for histopathological assessments, and it may reveal amyloid deposits, vasculitis, epithetioid granulomas, and invasion of lymphoma. In addition to these relatively disease–specific findings, nerve biopsy is also useful to demonstrate demyelination and axonal degeneration. Macrophage–mediated demyelination, widely spaced myelin, and uncompacted myelin lamellae are representative myelin abnormalities associated with chronic inflammatory demyelinating polyneuropathy (CIDP), anti–myelin–associated glycoprotein neuropathy, and POEMS syndrome, respectively. As for axonal neuropathies, large–fiber predominant loss is associated with Sjögren's syndrome, paraneoplastic syndrome, thiamine deficiency, and folate deficiency, while small–fiber predominant loss may be seen in patients with alcoholism, amyloidosis, Fabry disease, and diabetes. However, recent studies suggested that the modality of nerve fiber loss is more diverse even in a single etiology than previously appreciated. Physicians should carefully interprete the findings obtained by nerve biopsy.