Recovery of caloric function in experimental perilymph fistula

Twenty of 46 guinea pigs with experimental perilymph fistula that showed canal paresis on an ice water caloric test during the first week after operation were studied on the following days to observe the progression and final outcome of the caloric test. Two weeks after operation, 12 animals showed persistent canal paresis, whereas 8 animals developed a normal caloric response. Resolution of the caloric response progressed from canal paresis, via caloric irregularity, to a final return of normal caloric response. Morphological study of animals with recovery of caloric function shows healing of the previously ruptured membrane, with preservation of the contour of the membranous labyrinth in the lateral semicircular duct, and intact sensorineural elements. Recovery of caloric function may serve not only as an important diagnostic sign in patients with healed perilymph fistula, even without surgical proof, but also as an expectation for the recovery of hearing loss.