[Experimental perilymphatic fistula].

The round window membrane of the inner ear of 15 guinea pigs was removed under ketamine anaesthesia. Perilymph was aspirated through the round window in 8 guinea pigs. The round window membrane had regenerated spontaneously after 2 weeks. Light microscopy revealed hair cell loss localized to the apical and basal turns of the cochlea. Morphological examinations showed the most severe changes in these group of aspirated animals. Abrupt pressure imbalance may be a causative factor of sensorineural hearing loss.