Muscle involvement in association with filarial chyluria.
Twenty unselected consecutive patients of filarial chyluria were evaluated clinically, electromyographically, and histopathologically for neuromuscular dysfunction. None of the patients showed clinical evidence of muscle wasting or weakness suggesting myopathy, although generalized muscle weakness was complained by all of them particularly while climbing the stairs or on getting up or during lifting heavy weights. Electromyographic abnormalities were found in nine patients and slight histopathological abnormalities in two. The average duration of motor unit potentials and the mean amplitude were reduced, compatible with myopathy. There were no fibrillation potentials. Histological abnormalities consisted of a marked variation in muscle fibre size, sarcolemmal nuclear proliferation, and mild interstitial fatty infiltration. None of the patients showed evidence of clinical neuropathy, abnormalities in conduction velocity along the nerves or signs of segmental demyelination in the biopsy of the nerve. Our data suggest that muscle weakness in these patients is myopathic in nature without peripheral nerve involvement, and is possible due to hypoproteinaemia and hypolipidaemia, as these patients lose excessive amounts of protein and fat in their urine.