Bilateral duplication of the internal auditory canal: a case with successful cochlear implantation.

We report a case of bilateral duplication of the internal auditory canal (IAC). An 11-month-old girl with congenital profound hearing loss was referred to our hospital. Imaging evaluations revealed bilateral IAC duplication, which contained the facial and cochleovestibular nerves in one canal, but no nerves in the other. She underwent cochlear implantation. At 5 months after surgery her hearing thresholds with the cochlear implant are 40 and 45dB at 2000 and 4000Hz, respectively. Bilateral duplicated IAC is extremely rare, with seven cases reported in the literature. This case represents a previously unreported type of IAC duplication, and is the first case in which cochlear implantation was successfully performed.