Neonatal Changes in the Endolymph and Their Possible Relationship to Peri-Natal Deafness

Abstract

The electrochemical changes in the cochlear endolymph were investigated in rats aged 8 to 18 days. The endocochlear potential was very small until the 12th day, when a 50 mV increase occurred in 48 hours, but the ionic concentrations were already mature on the earliest day studied. The extremely rapid potential increase appears to be associated with fundamental membrane changes and the cochlea thus seems to pass through a critical and potentially hazardous developmental phase at this time. Such a phase seems important in the pathogenesis of genetically-determined deafness in animals but may be less so in man. However, due to its early maturation, the human cochlea is uniquely vulnerable to peri-natal anoxia and this may initiate degeneration in the presence of other deleterious factors.