ANTWERP PAPERS IN LINGUISTICS 102 Language acquisition in very young children with a cochlear implant

This symposium aims at sharing the preliminary data that are available on language acquisition in very young children with a cochlear implant. Congenital sensorineural hearing loss occurs in approximately 2 per 1000 newborns and results in significant and often irreversible retardation in the development of speech and language. Early detection is possible thanks to universal hearing screening programs. Early intervention consists of hearing aids or cochlear implants in case of severe losses followed by intensive (re)habilitation. Hearing aids are provided at ages as young as 3 months, but cochlear implants are not yet provided routinely before the age of 2 years. A trend however exists towards younger implantation, even before the age of 1 year, and it is anticipated that this will significantly influence the speech and language development of these children. Preliminary data are available on the audiological outcome of very young implantation and they will be presented. In addition, it is also important to assess the speech and language development of these children and to compare this with both normally hearing children and hearing impaired children with a hearing aid during the first years of their life. An attempt will be made to define relevant outcome measures in terms of speech and language development and some first results will be presented. Congenital hearing loss Congenital bilateral sensorineural hearing loss (>30 dB HL) occurs in approximately 1.2 to 3.2 per 1000 live births (Watkins 1991, White 1993, Mauk 1993, Parving 1993, Davis 1994, Northern 1994, Fortnum 1997, Stein 1999). This hearing loss is permanent and results in significant delay in speech and language development and consequently in important integration problems in the mainstream educational system (Brannon 1966, Davis 1974, Davis 1986, Andrews 1991, Geers 1989). Deaf-mutism is the most extreme consequence and this has been part of all cultures in human history. Until recently, no other therapy than hearing aids existed. Because of factors that will be discussed later, even hearing aids were unable to restore hearing sufficiently to prevent these severe consequences of congenital deafness. This situation has dramatically changed in the last decade. The reason for this is the development of cochlear implants in the late seventies. These are implantable electronic devices that aim at replacing the cochlear function. Initially these implants were used to restore hearing in elderly patients with acquired deafness. With time, and encouraged by improving results and technology, the field of indications broadened towards younger patients and lower degrees of hearing loss. Initially congenital (or “prelingual”) deafness was considered a relative contraindication for cochlear implantation, because it was observed that these persons with severe speech and language retardation hardly improved after the intervention. However it was felt by many professionals in the field that cochlear implants could have significant impact on the speech and language development if they could be implanted at sufficiently young an age, meaning before the onset or at a very early stage of the linguistic development. For this to become possible, it would be crucial to detect congenital hearing losses at a very early stage and to develop proper diagnostic tools to gain certainty about the type and degree of hearing loss. Fortunately and in parallel with the development of cochlear implants, new techniques became available to easily detect hearing losses in newborns. These techniques were based on the otoacoustic emissions that were discovered as a physiological entity in the late seventies (Kemp 1978). Commercial equipment became available in the late eighties and this was the incentive to start thinking of universal neonatal screening programs in order to detect all congenital hearing losses immediately after birth (White 1993). To date, universal neonatal hearing screening is a fact in several regions in the world. Infants with congenital hearing loss are receiving elaborate diagnostic work-up and they typically receive their first hearing aids by the age of 3 months. Audiological tools exist that allow early selection for cochlear implantation, which can be safely done before the age of 1 year.