Epidemiology of hearing impairment at three Flemish institutes for deaf and speech defective children

Abstract A retrospective analysis of 190 records of hearing impaired children up to the age of 14, all educated at one of three Flemish Institutes for Deaf and Speech Defective Children in Belgium, was performed. Until 1999, the well-known behavioral test (Ewing test) was used in the Flemish national screening program for hearing losses. Because it presented a lot of disadvantages, it has been replaced by Automated Auditory Brainstem Responses (AABR), enabling the Flemish national neonatal screening program to commence. This study is an extension of the preliminary results of a recently performed retrospective analysis in one Flemish institute of the hearing loss of patients that were diagnosed in the pre-AABR era. The authors analyzed the following data: etiology, risk factors of congenital hearing impairment, the patient's history from the moment of the first suspicion to diagnosis and treatment. The median age of the children was 8.5 years (2–14 year). In 66.5% the parents and/or grandparents were the first to raise suspicion, this was at a median age of approximately 9 months. The diagnosis was often made late, at a median age of 15 months (0–88 months). The etiology was unknown in 32.6% of the cases. The only cast-iron certain diagnoses were pre- and perinatal infections, syndromal and genetic hearing loss, and acquired infections (meningitis and measles). No risk factors of hearing loss, as they are stated by the Joint Committee on Infant Hearing, were found in more than 50% of the cases. Audiometry was performed in all cases, often supplemented with Auditory Brainstem Responses and/or click-evoked otoacoustic emissions, while other diagnostic investigations (imaging, genetics, etc.) were only variably performed. Finally, the authors confirm the need for universal neonatal screening, which only recently started in Belgium, and suggest that a detailed protocol should be established to persue a coherent diagnostic policy.