Labyrinthine fistulae: pathobiology and management

Abstract

This article reviews literature on three manifestations of these pathologic mechanisms: leakage of perilymph from the inner ear into the middle ear, disruption of the bone of the labyrinth caused by cholesteatoma or other manifestations of chronic otitis media, and superior semicircular canal dehiscence syndrome. Labyrinthine fistulae are caused by abnormal communications between the inner ear and surrounding structures. Under normal circumstances, the fluid-filled spaces of the membranous labyrinth are encased in the dense bone of the otic capsule with only two places of increased compliance: the oval window and the round window. Disruption of the labyrinthine bone can lead to areas of increased compliance, with symptoms and signs that can be understood based upon abnormal pressure transmission in the system. Communication between the endolymphatic and perilymphatic spaces of the labyrinth or passage of perilymph from the labyrinth into the middle ear or mastoid can lead to hearing loss and/or vestibular disturbances. Findings on clinical examination as well as CT imaging of the temporal bone can be useful in making the diagnosis. Management is based upon the specific pathological factors and the impact of the symptoms and signs on the patient.