AGE-RELATED DECREASES IN ENDOCOCHLEAR POTENTIAL ARE ASSOCIATED WITH VASCULAR ABNORMALITIES IN THE STRIA VASCULARIS

The density and diameter of strial capillaries were assessed in whole- mount preparations of the cochlear lateral wall from 18 gerbils aged i n quiet for at least 36 months. Following morphometric analysis, histo pathologic changes in selected regions of the lateral wall were examin ed by light and transmission electron microscopy. Alterations in stria l vasculature were compared with the endocochlear potential (EP) measu rements from the same ear. Vascular degeneration occurred in a segment al fashion in that regions of atrophic capillaries were found througho ut the cochlea but primarily in the apieal and lower basal turns and i n the hook. The amount of stria with normal capillaries varied greatly among the aged ears, ranging from 19 to 87%. The resting EP also vari ed markedly, ranging from 23 to 83 mV. Little correlations were found between the total strial area with normal vasculature and both the mea n EP value and that recorded at either the round window or first turn in that ear.