Cochlear implantation outcome in prelingually deafened young adults

Subjects with post-lingual profound deafness almost invariably benefit from cochlear implantation whereas a number of variables influence the outcome of prelingually deafened adults such as duration of deafness, hearing aid use before cochlear implantation, mode of communication and administration of auditory-oral speech therapy. This study evaluated speech perception performances in a group of eighteen prelingually deafened adolescents or young adults (6 females, 12 males; mean age at implantation 19.9 range 13-30 years) who underwent cochlear implantation at our institution and were followed up for three years. In order to keep heterogeneity to a minimum we included only those patients satisfying the following criteria: profound hearing loss, onset of deafness at an age lower than 3 years, age at implantation higher than 12 years, no evidence of mental retardation, hearing aid fitting since early childhood, substantial functional gain as indicated by aided thresholds, oral communication and auditory-oral training throughout school years and for no less than one year after receiving cochlear implant. Word discrimination length, word and sentence identification, phoneme identification and word and sentence recognition were tested before cochlear implantation and at 6 months, 1, 2 and 3 years of cochlear implant use. The results were: 1) Scores on all tests significantly improved after cochlear implantation although mean values were lower compared to those achieved by post-lingually deafened patients; 2) Speech performances on both word and sentence recognition showed a progressive increase from six-month to three-year follow up; 3) Better performances were observed in the sentence recognition task as compared to disyllabic and trisyllabic words at three years of cochlear implant use. We suggest that the presence of an auditory input delivered by hearing aids before cochlear implantation together with auditory-oral therapy and a good level of education may positively influence the cochlear implant outcome in prelingually deafened adults.