Cochlear vascular and sensory cell changes induced by elevated temperature and noise.

The vascular anatomy of the chinchilla cochlea was quantitatively analyzed and compared in animals exposed to 155- or 160-dB impulse noise at normal (37 degrees C) and elevated (40 degrees C) body temperatures. Vascular changes persisted 45 days after noise exposure in all experimental animals. Six variables were most susceptible to change in one or more of the vessels studied: 1) irregularities in the vessel lumen, 2) plasma spaces between red blood cells (RBCs) and the vessel wall, 3) columns of RBCs, 4) variability in density of RBCs, 5) pigment clumps in the stria vascularis, and 6) perivascular cells compressing the vessel lumen. These vascular changes, which indicate a reduction in blood flow, were present throughout the length of the cochlea, with a tendency toward maximum change in areas of maximum hair cell loss. There was no evidence in the vascular results to support an interaction between noise and increased body temperature. However, the cochleograms from the experimental animals indicate that at the 160-dB exposure level the noise and high temperature may have interacted to increase hair cell loss.