[Structural and ultrastructural quantitative study of skin and nerve biopsies in the diagnosis of congenital indifference to pain].

The muscolo-cutaneous nerve, and skin biopsies from 3rd and 5th finger-tips and the back were studied in a 8-year-old girl with congenital indifference to pain, and in a control child of the same age. The tips of the fingers, and the toes were the most damaged areas. The diameters of myelinated and unmyelinated fibers of the nerve in the sick child and the control child were compared. A loss of 54% of myelinated fibers and 33% of unmyelinated fibers was observed. In the skin, the loss of myelinated fibers was 82% in the 3rd finger-tip, 78% in the 5th, and 35% in the back, and of unmyelinated fibers, 97%, 87%, and 8%, respectively. Eighty four per cent of free endings were absent in the 3rd finger-tip and they were completely absent in the 5th. As for Meissner's corpuscles, 97% were absent in the 3rd finger, and 75% in the 5th. The absence of degenerating fibers and the unimodal distribution of unmyelinated fibers raise the problem of the nosological position of this case of congenital indifference to pain, as compared to the sensory neuropathies.