Click-evoked otoacoustic emissions in a child with unilateral deafness.

In a 6-year-old boy with idiopathic unilateral deafness, click-evoked otoacoustic emissions were recorded in both ears with similar amplitudes and time courses. Following stimulation of the deaf ear, no component of auditory-evoked brainstem potentials was recorded. No space-occupying lesion was observed with high-resolution CT. At retest 1 year later these results were unchanged. In the deaf ear electrostimulation of the cochlear nerve was performed using an ear canal electrode. At a stimulus current of 20 microA the body consistently reported hearing sensation. Click-evoked otoacoustic emission indicated good outer hair cell function. Hearing sensation at low stimulus intensities with electrostimulation indicated fairly good functions of the cochlear nerve. Considering also the results of imaging and auditory-evoked potentials, findings suggested that the deafness was due to an inner hair cell disorder.