목적: Unlike most forms of nonsyndromic recessive hearing loss that show congenital severe to profound hearing loss, considerable proportion of patients with enlarged vestibular aqueduct caused by SLC26A4 mutations demonstrate residual hearing loss initially that eventually progress. Thus, many patients with SLC26A4 mutations become candidates for cochlear implantation in the 2nd or 3rd decade. Since cochlear implantation in prelingual adults has demonstrated poorer results compared to that performed in children or postlingual adults, we analyzed the outcome of cochlear implantation in this special group of patients with congenital hearing loss who were implanted in their adolescent or adult periods. 방법:Sixteen patients with enlarged vestibular aqueduct carrying biallelic SLC26A4 mutations who received cochlear implantation after 12 years of age were included for analysis. The outcome and prognostic factors of cochlear implantation were analyzed. The postoperative follow-up period ranged from 3 to 48 months. 결과:The age at cochlear implantation ranged from 12 to 44 years. The CAP score was significantly improved after cochlear implantation from 3.1 to 4.9 (P<0.05). The mean sentence scores improved significantly in the auditory-verbal and auditory-only conditions (P<0.05). Of the six patients who did not show significant improvement in the auditory-only condition, all but one patient demonstrated significant improvement in the auditory-verbal condition. Factors related to poorer outcome after cochlear implantation included use of sign language, no measurable bone conduction hearing, nonuse of hearing aids preoperatively, absence of a recent history sudden hearing loss, and low speech intelligibility rating. 결론:Despite the delayed timing of cochlear implantation in patients with SLC26A4 mutations showing prelingual onset of hearing loss, significant improvement in auditory performance can be expected after cochlear implantation.