Abstract
The authors had reported some clinical cases of sodium bromate intoxication showing a severe hearing loss and uremia. In this paper, the effects of sodium bromate on the inner ear were experimentally studied. The chemical was given intramuscularly 100 to 200mg/kg body weight and the endocochlear DC potential (EP) was measured for judgement of inner ear function. At the times when EP showed 50% of normal and 0mV, the animals were sacrificed and the stria vascularis was observed electronmicroscopically.
The stria vascularis in the animals showed 50% level of normal EP revealed no change in the marginal cells, the intermediate cells and the basal cells.
In the animals which EP decreased to 0 mV, the marginal cells degenerated and the intercellular space was enlarged in the early stage and then the cytoplasm of the marginal cells was ejected into the endolymphatic space. Finally the endolymphatic space was almost collapsed and the Reissner's membrane closely touched to the surface of the marginal cell. These findings in the stria vascularis were very variant in each animals. According to the results obtained it is concluded that in the sodium bromate intoxication the hearing loss starts at the marginal cell of the stria vascularis and the degeneration is irreversible.
