Common Cavity Deformity

Abstract

Common cavity (CC) deformity is a severe inner ear malformation accompanied by profound hearing loss. However, the cochlear nerve distribution in the CC is unknown in this deformity. We studied the electrically evoked auditory brainstem response (EABR) during cochlear implant surgery and the postoperative development of speech and hearing ability in children with CC deformity to determine the presence or absence of physiological auditory function in this type of severe inner ear malformation. Nine children who were congenitally deaf with profound hearing loss were found to have CC deformities by temporal bone computed tomography (CT) and magnetic resonance imaging (MRI). All of these children underwent cochlear implant surgery. Their EABRs were recorded during cochlear implant surgery and their postoperative development of speech and hearing ability was evaluated periodically as they aged. Their modes of communication and their educational levels were assessed on multiple followed ups. All of the nine children with CC deformities showed that their eV mean peak latencies of their EABRs were 3.9 ± 0.2 ms which were the same as the controls and the eV mean peak thresholds were twice as high compared with controls and they showed marked improvement of their postoperative hearing thresholds of between 30 and 40 dBSNL.