Het cochleair implantaat

Abstract

A cochlear implant (CI) can partially restore the hearing of individuals with perceptive deafness. The CI stimulates the auditory nerve directly via an electrode in the cochlea. The ability of a person to understand speech when using a CI depends on whether deafness occurred pre- or post-lingually, before or after the development of hearing, language, and speech. Post-lingually deaf adults and pre-lingually deaf children can achieve a high level of speech perception with a CI. In contrast, pre-lingually deaf individuals who receive a unilateral CI at an older age perform substantially worse, but may benefit from a CI as support for lip-reading. Eight academic centres in the Netherlands implant CIs. Children are eligible for a CI if they have a hearing loss of more than 60 dB at the frequencies 2000 and 4000 Hz, despite using the best available hearing aids. For adults these criteria include a pure tone average of more than 90 dB and speech perception scores lower than 60% with the best available hearing aids. Nowadays, children with congenital deafness younger than 5 years are given bilateral CIs, preferably before 1 year of age. CIs are implanted sequentially in congenitally deaf children and adolescents aged 5–18 years. Contraindications for bilateral implantation are poor experience with earlier implants and congenital deafness in children older than 12 years who have not yet received a CI. Children with acquired deafness are also eligible for bilateral CIs. The need for, and effectiveness of, bilateral CIs in adults and deaf–blind individuals are disputed and currently costs are not reimbursed by Dutch health insurance companies.