Surgical considerations regarding cochlear implantation in the congenitally malformed cochlea.

A 4-year-old girl with congenital profound deafness underwent cochlear implant surgery. Preoperative CT and MRI revealed that her inner ears had common-cavity or aplasia-type malformation. The bilateral internal auditory meatus were markedly narrowed. Audiometric examination demonstrated that only slight residual hearing remained in the low-frequency range and that a hearing aid would be of no benefit. Cochlear implantation was performed in her left ear. Because of the abnormal position of the facial nerve, the routine facial recess approach could not be performed. A canal-wall-down mastoidectomy was performed, and multichannel cochlear implant electrodes were inserted by careful drilling of the bony wall of the semicircular canal area. All 22 electrodes were completely inserted into the cavity. The patient can perceive sounds and her hearing ability is progressively improving.