Role of air bubbles in the perilymph as a cause of sudden deafness

In the course of exploratory tympanotomies we have several times come across air bubbles leaking with perilymph. The fact prompted the hypothesis that in some cases of perilymphatic fistulas, air bubbles could enter the perilymphatic space from the fistula of the inner ear membrane and cause acute, reversible, profound sensory hearing loss. The experimental study described here was designed to test this hypothesis on guinea pigs. Experiments showed that sudden elevation of middle ear pressure by artificial means caused air bubbles to appear in the scala tympani even at a pressure level of 400 mm H2O. It also proved that air bubbles entered the perilymphatic space through the ruptured round window membrane without damaging Corti's organ or the membranous structure of the cochlea. Sequential recording of the action potential revealed that air bubbles induced acute, reversible, and profound hearing loss of cochlear origin, probably by disturbing the propagation of traveling waves of the perilymph.