[Neuropathies of unknown etiology. A study of 48 cases]

A prospective study, carried out over 7 years, showed that out of 432 peripheral neuropathies followed up for 12 months, no cause could be discovered in 48 (11%). This is discussed with respect to the previous few reports. In fact none of these studies is strictly comparable. In spite of complementary investigations and observation of the course of the disease, it may be difficult to be sure to which etiology any individual case belongs; e.g. genetically determined neuropathies, chronic inflammatory polyradiculoneuritis or drug-induced neuropathies. However, it is clear that the group of neuropathies of undetermined origin, is clinically, pathologically and developmentally heterogeneous. This suggests that these patients should be classified as having a yet undetermined disease process. In our series, long term follow up enabled us finally to find a cause in a significant number of cases.