Hearing impairment among children in Saudi Arabia: familial incidence and potential risk factors.

A comprehensive clinical and laboratory study was carried out to elucidate the aetiology, risk factors, and familial incidence of hearing impairment. The study involved 1072 children at risk for hearing impairment as well as 17 families. Evaluation of the mothers' clinical histories/findings suggested that the leading possible risk factors for hearing impairment in children were frequent pregnancies, miscarriages and low birth weight. Hearing and/or speech problems in siblings, parents, or even grandparents, were noted to be of significance in hereditary transmission. Among 42 clinically-diagnosed and laboratory confirmed cases, the aetiologic agent found to occur most frequently was, unusually, herpes simplex virus type 1, a non-TORCH agent. Second in frequency of occurrence was Toxoplasma gondii. There was IgM positivity for multiple agents including rubella virus with cytomegalovirus. In the family study, a reliable laboratory confirmation of clinically-diagnosed hearing impairment was obtained in 10-17 families (58.8%). An interesting finding, and one which concurred with clinical histories/findings, was that the incidence of hearing impairment could be reliably correlated with high positivities to IgG, particularly cytomegalovirus.