Effect of perilymphatic air-perfusion on cochlear potentials.

The hypothesis that acute, profound and reversible sensorineural hearing loss occuring in some cases of window rupture is caused by air-intrusion into the perilymphatic space at the time of rupture of the inner ear membrane (s) was tested by the introduction of air into the perilymphatic space of the guinea pig cochlea and the recording of cochlear potentials.Perfusion of the scala tympani with air at a rate of 200 or 400 μl/mmn initially caused a slight decrease of EP (10-15mV), probably due to the pressure effect, but the EP (although recordings were notchy) remained at this level throughout the perfusion lasting for 20-30 minutes and returned quickly to the original level when perfusion was stopped. In contrast, the CM and AP showed a marked (but reversible) decrease during the air perfusion.This study shows that the replacement of the scala tympani with air causes hearing impairment probably due to a reversible interference with the CM and AP production mechanisms rather than to strial dysfunction.