Progressive hearing loss after transverse temporal bone fracture.

Transverse fractures often violate the otic capsule and commonly, although not invariably, result in immediate and profound sensorineural hearing loss. The pathogenic mechanisms producing sensorineural hearing loss include direct trauma to the cochlear nerve, disruption of the membranous labyrinth, vascular compromise or hemorrhage into the inner ear, perilymphatic fistula, and endolymphatic hydrops. The last two mechanisms account for the occasional patient who develops progressive sensorineural hearing loss after the initial insult. On early posttraumatic evaluation three patients were discovered to have transverse fractures and residual auditory function. Deterioration of hearing led to middle-ear exploration with closure of perilymphatic fistulas. Hearing was preserved in two patients. Diagnosis of posttraumatic perilymphatic fistulas requires early audiometric assessment, high-resolution computed tomographic scanning of the temporal bones to detect fracture of the otic capsule and pneumolabyrinth, and a high index of clinical suspicion.