Cochlear implantation in patients with cochlear malformations.

Abstract

To report operative findings, postoperative course, and postimplantation performance in patients with cochlear malformations who underwent cochlear implantation. Case study and intervention study (before-after trial). Minimum follow-up of 12 months; average follow-up of 24 months. Academic tertiary referral center. Six patients, including five children who underwent implantation at ages 3.5 to 13 years and one adult who underwent implantation at age 27 years. malformations included common cavity deformity (n = 1), cochlear hypoplasia (n = 2), and incomplete partition (n = 3). All patients with cochlear malformations who underwent implantation at the University of Michigan, Ann Arbor, are included, selected from a group of 196 patients so treated since 1986. Implantation with a standard multichannel cochlear implant. Operative findings described include round window and facial nerve anatomy and cerebrospinal fluid leak. Postoperative roentgenographic findings, electrode activation, and reason for non-use of electrodes were investigated. Standard tests of speech perception were used to compare preoperative and postoperative performance for each subject. Operative findings included round window abnormalities (three patients), anomalous facial nerve (one patient), and cerebrospinal fluid leak (three patients). No surgical complications occurred. A minimum of 10 electrodes were activated for all patients. Electrode thresholds and discomfort levels were variable for several months after implantation. All patients demonstrated improved performance after implantation. Four subjects demonstrated open-set speech perception. Two other subjects, whose poor language skills precluded administration of standard tests, showed increased awareness of environmental sounds and increased vocalization after implantation. Cochlear implantation can be a successful method of rehabilitation in patients with congenital deafness who have cochlear malformations.