Usefulness of the Bilateral Cochlear Implant in Children

PICHON-RIVIERE, A.; AUGUSTOVSKI, F. A.; GARCIA MARTI, S.; GLUJOVSKY, D.; ALCARAZ, A.; LOPEZ, A.; BARDACH, A.; CIAPPONI, A; REY-ARES, L.

Documento de Evaluación de Tecnologías Sanitarias

IECS

Año: 2012 p. 1 - 30

1668-2793

Based on the information provided by the World Health Organization (WHO) in 2005 there were 278 million people with moderate or deep hearing impairment worldwide; 80% of them living in low and middle-income countries.It is calculated that half of the cases of deafness and hearing impairment may be avoided by early prevention, diagnosis and treatment. In developing countries, less than 1 every 40 people have their hearing needs treated. Current production of hearing aids meets less than 10% of the world needs.The Argentine Ministry of Health estimates that 1 to 3 out of 1,000 live births are babies with hypoacusia.In infants and preschool children early detection and treatment prevent problems in language development and school performance; in addition, adults with hearing impairment benefit in their work and personal lives when having access to adequate hearing aids, are trained in their use and have a follow up of their condition.TechnologyCochlear Implant (CI) is an electronic device consisting of an internal structure which allows stimulation of the hearing nerve fibers after surgical implantation and an external one that receives, analyzes and encodes the sounds. Both the internal and the external structures are connected by a cable and a magnet. Multichannel implants are currently in the market and provide a higher capacity for speech understanding. Bilateral cochlear implantation may be simultaneously or sequentially carried out.As with unilateral CI, this technology has different stages: adequate screening of the patients, surgery, rehabilitation and follow up, which implies creating multiple discipline teams including ENT specialists, speech therapists and psychologists. Setting the processor is carried out individually and is standard for each ear. Also, balancing or adjustment of both implants shall be carried out later to maximize the bilateral hearing benefit.PurposeThe purpose of this report is to assess the evidence available on the efficacy, safety and issues related to coverage policies of the use of Bilateral Cochlear Implants in children with deep hearing impairment or deafness.MethodsA bibliographic search was carried out on the main databases: DARE, NHS EED, on Internet general search engines, in health technology evaluation agencies and health sponsors. Priority was given to the inclusion of systematic reviews; controlled, randomized clinical trials (RCTs); health technology assessments and economic evaluations; clinical practice guidelines and coverage policies of other health systems.ResultsOne systematic review and 4 studies published after the date of the review search, 7 coverage policies and 2 health technology assessments were found.The systematic review found weak evidence of the benefit of bilateral CI for the speech perception in quiet and in noise; no conclusions could be drawn due to the heterogeneity of the included studies. The authors believe that time elapsed from implant placement (the longer the time between placement of the first and second CI is, the less benefits would be obtained) and the benefits attributable to the second implant improve with use time seem to be important.An observational study (retrospective cohort) assessed the capabilities of pre-verbal communication in 69 children (42 with unilateral CI and 27 with bilateral CI), all of them under 3 years old when implanted with unilateral or bilateral CI, using a multiple regression model and found that the use of bilateral CI accounts for 51% variability (p<0.0001) after adjustment by the age the implant was placed and length of deafness (time elapsed with no amplification or implant).In an observational study conducted by Lovett et al, studying 50 children with unilateral or bilateral implants, bilateral implantation proved to be associated with an increase in the precision of sound localization by 18.5% (95% CI 5.9 to 31.1) and speech perception in noise by 3.7 dB (95% CI 0.9 to 6.5 dB).In a longitudinal study where 29 children with bilateral CI were followed and its results were compared with those of 9 children with unilateral CI. The authors found no differences as to speech perception in quiet but found differences in noise which were significantly higher in those children with bilateral CI (difference of 10.1 dB p<0.01). Within the group of children with bilateral CI, the rate of children capable of precisely telling where the sound came from (lateralization) increased from 57% 6 months after implant placement to 83% after 24 months.The authors observed that the age when the second implant was placed had no influence at all on any of the study endpoints and the longer use time of the second implantation, the better the benefits.One study decided to determine if adolescents and young adults had any benefit from sequential bilateral CI and found out that the performance of 6 out of 9 participants in the Adaptive Spondee Discrimination Test was better in the bilateral condition when noise was presented ipsilateral to the implant (mean difference 3.7 dB; SD 2.7; p<0.001).As to coverage policies, both government agencies and private insurance companies provide coverage of a second cochlear implant in those patients who do not or will not benefit from the use of non implantable hearing aids and in some special cases (e.g., blind patients or patients at risk of cochlear ossification).ConclusionsIn children with acute hearing impairment or bilateral deafness whom amplification using hearing aids is not effective, the use of bilateral cochlear implants seems to be beneficial as to perception of speech in noisy settings and sound location in space (lateralization). In addition, one study showed that young children (less than 3 years old at the time of CI implantation) with deep deafness are prone to use verbal communications instead of signs and to use hearing without visual support when interacting with hearing people. The age at which second implantation is carried out does not seem to influence the benefits obtained which are more evident the longer time since implantation.