Hearing impairment in a patient with unilateral narrowing of the internal auditory canal--a case report.

A 9-year-old boy complaining of left hearing loss with unknown date of onset visited our clinic. The pure tone audiogram showed profound hearing loss in the left ear, while normal in the right ear. Computed tomography and magnetic resonance imaging showed narrowing of the left internal auditory canal (IAC) in contrast with the right IAC. Distortion Product Otoacoustic Emissions of the left ear were not present above the background noise at any frequency tested in contrast to the right one. A retrocochlear lesion might be accompanied, while the profound hearing loss was thought to be caused mainly by a cochlear lesion.