Changes in prevalence, aetiology, age at detection, and associated disabilities in preschool children with hearing impairment born in Göteborg.

The prevalence of hearing impairment (HI) in preschool children born in Göteborg in 1980 to 1984 was 2.0 per 1000. This was significantly lower than the 3.8 per 1000 found in a previous study for 1970 to 1974. The decrease took place in the moderate to severe range of HI, while deafness and mild HI remained unchanged during the period. The cause was considered to be prenatal in 58% with heredity in 33% as the main causative factor. Following the introduction of the MPR (Morbilli-Parotitis-Rubella) vaccination programme in Sweden, no cases of rubella- or mumps-induced HI could be found. The number of HI of perinatal origin decreased by half, in spite of the fact that the figures for preterm baby survival almost doubled during the period. Associated disabilities were diagnosed in 62% of the children with HI; speech retardation in 33%, visual abnormalities in 30%, mental retardation in 12% and neuropsychiatric disorders in 9% of the cases. The importance of collaborative efforts between the otolaryngologist and the neurologically and neuropsychiatrically interested paediatrician in the complete evaluation of additional difficulties in the HI child is emphasized.