Experimental perilymphatic fistulas

Objectives: Do experimentally induced perilymph fistulas in animals cause specific cochleovestibular symptoms? Material: Review of the recent literature on animal experiments of perilymph fistulas (back to 1990), An attempt was made to distinguish between 'pure fistulas' of the round window membrane and experimental setups with potential additional lesions of the inner ear. Results: Pure fistulas of the round window membrane did not affect the auditory thresholds or cause vestibular symptoms. There were however decreased distorsion product otoacoustic emissions, increased summation potentials and inconsistently decreased acoustic-evoked compound action potential amplitudes at high stimulation intensities. Experiments with potential inadvertently induced or controlled additional lesions of inner ear structures caused only slightly more serious symptoms. Conclusions: Isolated fistulas between the perilymphatic space and the middle ear cavity do not cause important cochleovestibular dysfunction. If such symptoms occur, they are probably caused by additional inner ear lesions. There are no evidences from animal experiments that surgical sealing of a fistula has a beneficial effect on these symptoms.