STUDIES ON SURAL NERVE BIOPSIES IN ENDEMIC SKELETAL FLUOROSIS

Sural nerve biopsies from 13 patients with radiologically confirmed sk eletal fluorosis were studied for myelinated fibre densities, frequenc y distribution of their diameters, and single teased nerve fibre prepa rations. It was observed that most of the biopsies showed a marked red uction in myelinated fibre densities with more than half of them invol ving the smaller fibres of less than 7 mum diameter. Teased fibre meas urements of internodal lengths and intermodal diameters point to myeli nated fibre dropout being due to axonal degeneration with secondary de myelination. The selective loss of small fibres is unlikely to be due to an entrapment neuropathy alone, and possibility of primary toxic in jury needs to be considered.