Perivascular demyelinization of cochlear neurons in two neonates.

Localized perivascular demyelinization of the peripheral processes of cochlear neurons was observed in surface preparations of the osseous spiral lamina in two neonates, one a premature infant with erythroblastosis fetalis, the other a full-term infant with cyanotic congenital heart disease. In both cases the cause of the demyelinization was unknown. Both infants had severe edema as a result of congestive heart failure and anoxia. The serum bilirubin level in the erythroblastotic child appeared too low to have caused injury to the nerve fibers. The demyelinization was most striking in the lower half of the basal turn. It was observed only in the immediate vicinity of meandering stretches of capillaries as they crossed the nerve fibers. In the premature infant there was hair cell loss throughout the cochlea; in the other there was no hair cell loss, but a malformed labyrinth of the Mondini type.