Surgical considerations regarding cochlear implantation in the congenitally malformed cochlea

A 4-year-old girl with congenital profound deafness underwent cochlear impl ant surgery. Preoperative CT and MRI revealed that her inner ears had commo n-cavity or aplasia-type malformation. The bilateral internal auditory meat us were markedly narrowed. Audiometric examination demonstrated that only s light residual hearing remained in the low-frequency range and that a heari ng aid would be of no benefit. Cochlear implantation was performed in her l eft ear. Because of the abnormal position of the facial nerve, the routine facial recess approach could not be performed. A canal-wall-down mastoidect omy was performed, and multichannel cochlear implant electrodes were insert ed by careful drilling of the bony wall of the semicircular canal area. All 22 electrodes were completely inserted into the cavity. The patient can pe rceive sounds and her hearing ability is progressively improving.