Abstract
Sensorineural hearing loss has various etiologies. One of them is perilymphatic fistula, which is observed in (1) congenital malformation of the internal ear in children:(2) after operations on the oval window (stapedectomy, interposition);(3) in cases of head trauma, and(4) in acute hearing loss of unknown origin. The authors report 5 of 19 cases of acute hearing loss observed at the ORL Clinic in Krakó and operated on by exploratory tympanostomy. In 4 of them, repture of the round window membrane (secondary tympanic membrane) was found. A hypothesis for the repture mechanism is presented.