title: Bilateral sequential cochlear implantation in the congenitally deaf child: evidence to support the concept of a 'critical age' after which the second ear is less likely to provide an adequate level of speech perception on its own.
abstract: This study attempts to answer the question of whether there is a 'critical age' after which a second contralateral cochlear implant is less likely to provide enough speech perception to be of practical use. The study was not designed to predict factors that determine successful binaural implant use, but to see if there was evidence to help determine the latest age at which the second ear can usefully be implanted, should the first side fail and become unusable.Outcome data, in the form of speech perception test results, were collected from 11 cochlear implant programmes in the UK and one centre in Australia. Forty-seven congenitally bilaterally deaf subjects who received bilateral sequential implants were recruited to the study. The study also included four subjects with congenital unilateral profound deafness who had lost all hearing in their only hearing ear and received a cochlear implant in their unilaterally congenitally deaf ear. Of those 34 subjects for whom complete sets of data were available, the majority (72%) of those receiving their second (or unilateral) implant up to the age of 13 years scored 60 per cent or above in the Bamford Kowal Bench (BKB) sentence test, or equivalent. In contrast, of those nine receiving their second or unilateral implant at the age of 15 or above, none achieved adequate levels of speech perception on formal testing: two scored 29 per cent and 30 per cent, respectively, and the rest seven per cent or less.A discriminant function analysis performed on the data suggests that it is unlikely that a second contralateral implant received after the age of 16 to 18 years will, on its own, provide adequate levels of speech perception. As more children receive sequential bilateral cochlear implants and the pool of data enlarges the situation is likely to become clearer.The results provide support for the concept of a 'critical age' for implanting the second ear in successful congenitally deaf unilateral cochlear implant users. This would argue against 'preserving' the second ear beyond a certain age, in order to use newer models of cochlear implant or for the purpose of hair cell regeneration and similar procedures in the future. The results suggest a new and more absolute reason for bilateral implantation of congenitally deaf children at an early age.
authors: Royal National Throat, Nose and Ear Hospital Cochlear Implant Programme, Grays Inn Road, London WC1X 8DA, UK. john.graham10@virgin.net
authors: John
authors: J
authors: Graham
authors: Debi
authors: D
authors: Vickers
authors: Julie
authors: J
authors: Eyles
authors: Julie
authors: J
authors: Brinton
authors: Ghada
authors: G
authors: Al Malky
authors: Wanda
authors: W
authors: Aleksy
authors: Jane
authors: J
authors: Martin
authors: Lise
authors: L
authors: Henderson
authors: Deborah
authors: D
authors: Mawman
authors: Philip
authors: P
authors: Robinson
authors: Elizabeth
authors: E
authors: Midgley
authors: Kate
authors: K
authors: Hanvey
authors: Tracey
authors: T
authors: Twomey
authors: Susan
authors: S
authors: Johnson
authors: Zebunnisa
authors: Z
authors: Vanat
authors: Cath
authors: C
authors: Broxholme
authors: Cecilia
authors: C
authors: McAnallen
authors: Agnes
authors: A
authors: Allen
authors: Monica
authors: M
authors: Bray
mesh_terms: D000293:Adolescent; D000328:Adult; D000367:Age Factors; D002648:Child; D002675:Child, Preschool; D019929:Cochlear Implantation; D003054:Cochlear Implants; D003423:Critical Period, Psychological; D006312:Hearing Loss, Bilateral / Q000151:congenital* / Q000601:surgery / Q000628:therapy*; D006801:Humans; D007223:Infant; D007804:Language Development; D008875:Middle Aged; D013067:Speech Perception; D016896:Treatment Outcome; D055815:Young Adult