[Metabolic and nutritional neuropathies]

The two main causes of metabolic neuropathies are successively diabetes and chronic renal insufficiency. Diabetic neuropathies include both diffuse polyneuropathies and focal neuropathies. Sensori(motor) polyneuropathy is the most frequent form and different therapeutic trials have been initiated on the ground of the vascular and metabolic factors implicated in its pathogenesis. Autonomic neuropathy is the major cause of morbidity and mortality. In patients with chronic renal failure, the polyneuropathy is improved by renal transplantation. The carpal tunnel syndrome is frequent in hemodialysis patients, and surgery gives the opportunity to look for beta-2-microglobulin amyloid deposits. Among the less frequent causes of peripheral neuropathies in which metabolic factors have been considered, we review hypoglycemia, chronic respiratory insufficiency due to chronic obstructive pulmonary disease, chronic liver diseases, and the polyneuropathy occurring in the critically ill patients with nutritional or metabolic failures. In chronic excessive drinkers peripheral neuropathy is classically associated with thiamine deficiency, but the direct effect of alcohol itself has been discussed. Various vitaminic deficiencies have been responsible for the development of peripheral neuropathies. The clinical forms often associate peripheral neuropathy with myelopathy, and serum vitamin E concentrations should be measured in patients with spinocerebellar disorders. Usually nutritional deficiencies need multivitamins supplementation.