Traumatic head injury is the principal cause of death and serious physical disability in adolescents and young adult. Hearing loss is a common sequela of head trauma. The results of pure tone and auditory brain-stem response (ABR) assessment of minor head injury revealed that 20 per cent of these cases showed impairment of hearing including both conductive and sensorineural heaing loss mostly in the high frequencies loss.
ABR findings showed a significant difference of absolute wave V latency and interwave (III-V) latencies at repetition rate 11.1 click/sec., and a highly significant difference at a repetition rate of 51.1 click/sec., compared with the control group.
In severe head injury, conductive hearing loss was found in only one case, in which a longitudinal fracture of the temporal bone was identified radiologically. No ABR could be recorded at a repetition rate of 11.1 click/sec. in either ear of this case; this patient died a few days later.
Three cases were found with a mixed sensorineural hearing loss; one of them showed a longitudinal fracture radiologically. ABR findings in two cases showed prolongation of wave V and I–V interwave latencies, and the third case showed absence of ABR recording.
In comatose patients, an ABR grading system is a more sensitive index of brainstem dysfunction than the simple division of normal versus abnormal ABR waves and interwave latencies. Presence or prolongation of wave V and interwave latency I–V even in one ear is of good prognostic value in the comatosed patient.