COCHLEAR IMPLANTATION IN PATIENTS WITH COCHLEAR MALFORMATIONS

Objective: To report operative findings, postoperative course, and pos timplantation performance in patients with cochlear malformations who underwent cochlear implantation. Design: Case study and intervention s tudy (before-after trial). Minimum follow-up of 12 months; average fol low-up of 24 months. Setting: Academic tertiary referral center. Patie nts: Six patients, including five children who underwent implantation at ages 3.5 to 13 years and one adult who underwent implantation at ag e 27 years. Malformations included common cavity deformity (n=1), coch lear hypoplasia (n=2), and incomplete partition (n=3). All patients wi th cochlear malformations who underwent implantation at the University of Michigan, Ann Arbor, are included, selected from a group of 196 pa tients so treated since 1986. Intervention: Implantation with a standa rd multichannel cochlear implant. Main Outcome Measures: Operative fin dings described include round window and facial nerve anatomy and cere brospinal fluid leak. Postoperative roentgenographic findings, electro de activation, and reason for nonuse of electrodes were investigated. Standard tests of speech perception were used to compare preoperative and postoperative performance for each subject. Results: Operative fin dings included round window abnormalities (three patients), anomalous facial nerve (one patient), and cerebrospinal. fluid leak (three patie nts). No surgical complications occurred. A minimum of 10 electrodes w ere activated for all patients. Electrode thresholds and discomfort le vels were variable for several months after implantation. All patients demonstrated improved performance after implantation. Four subjects d emonstrated open-set speech perception. Two other subjects, whose poor language skills precluded administration of standard tests, showed in creased awareness of environmental sounds and increased vocalization a fter implantation. Conclusions: Cochlear implantation can be a success ful method of rehabilitation in patients with congenital deafness who have cochlear malformations.