Auditory brainstem response: study of the air and bone conduction in infants with middle ear changes

ABSTRACT

Purpose  To compare the electrophysiological thresholds of the FS- ABR by air and bone conduction in infants with and without middle ear alterations, verifying the applicability of the air-bone gap in the differential diagnosis of the types of hearing loss and its relationship with the results of tympanometry and of the ABR click.

Methods  The sample was composed of 73 infants: study group (52 ears) with conductive alteration, absence of emissions, otoscopy and altered tympanometric curve, and the control group (82 normal ears). Click ABR was performed at 80 dB nHL and threshold research (click, 500 and 2000 Hz) was recorded by air and bone conduction. Tympanometry was obtained with a 1000 Hz probe (children up to six months of age) and a 226 Hz probe (older than six months).

Results  The control group had normal thresholds in air and bone conduction without gap. In both groups, air thresholds at 500 Hz were higher and in bone conduction thresholds at 500 Hz lower than at 2000 Hz. There was an association between gap, tympanometric curve and increased latency of wave I.

Conclusion  The FS-ABR BC can be considered a viable in the clinical practice of a public health service, which does not always have sedation. The associations of altered tympanometry and prolonged latency of wave I with air bone gap reinforce the clinical importance of the combination of AC and BC ABR by specific frequency as a viable and effective alternative in the diagnosis of conductive hearing loss in infants.

Keywords:  Brainstem auditory evoked potentials; Infant; Bone conduction; Auditory tests; Conductive hearing loss