Audiological outcomes of severe traumatic brain injury with base of skull fracture

Audiological outcomes of severe traumatic brain injury (TBI) with basal skull fracture were investigated in this study. Fractures of the skull base most commonly involve the temporal bone, and whilst much research has focused on audiological consequences of specific temporal bone fracture, audiological outcomes of the more commonly used base of skull classification are yet to be established. Participants were nine in-patients of a Brain Injury Rehabilitation Unit (BIRU) who had sustained severe TBI with basal skull fracture. Audiological assessment included pure tone, speech and impedance audiometry, auditory brainstem response (ABR) and distortion product otoacoustic emission (DPOAE) testing. Over half (55%) of the participants sustained hearing impairment, however, the degree and nature of the losses were variable. The degree of loss ranged from mild to profound, and sensorineural, conductive and mixed hearing losses were evident. Asymmetrical hearing thresholds were common, with the poorer ear being on the side that the fracture occurred. In cases where TBI resulted in brain stem dysfunction and abnormal ABR responses, DPOAEs provided valuable additional information about cochlear function. Three participants sustained both retrocochlear and cochlear dysfunction on the side of fracture. The implications of this study are twofold; one, all people with TBI and basal skull fracture should be referred for audiological assessment; and two, DPOAEs should be included in the audiological test battery