On the etiology of hearing loss in a population of 155 institutionalized children

In this paper we present the results of an etiological study in 155 hearing-impaired children and young adults, born between 1960 and 1984, inmates of the IRSA institute (Royal Institute for Deaf and Blind children). Special reference to genetic factors was given. One third of the inmates of this institute were children of immigrants, the majority Italians and North-Africans. The study revealed the following classification for the Belgian pupils: hereditary deafness 22.9%; acquired deafness 44.9% and deafness of unknown origin 32.1%; in the group of immigrants, it was 39.1%, 45.6% and 15.2%, respectively. Six of the 45 patients with a genetic form of deafness presented a distinct syndrome, Usher syndrome (2 patients) being the most frequent. Autosomal dominant inheritance was present more often in the deaf population than in the hearing-impaired population (hearing loss below 80 db), but the difference was not statistically significant. Even after 1980 congenital rubella remained the most frequent exogenous factor causing congenital deafness and, furthermore, we documented for the first time in a retrospective study cytomegalovirus infection as a cause of hearing loss. Atypical retinal abnormalities not related to congenital rubella syndrome were found in 10 inmates by systematic ophthalmological examination: 7 in the unknown group, 1 in the genetic group and 2 in the acquired (meningitis) group.