Congenital cytomegalovirus infection is the leading identified nongenetic cause of congenital sensorineural hearing loss. Most of the infections are asymptomatic but may be detected from umbilical cord vein and/or newborn serum positivity for human cytomegalovirus immunoglobulin M, and from urine positivity (on polymerase chain reaction) for human cytomegalovirus deoxyribonucleic acid in the newborn period. Children infected by cytomegalovirus may later develop sensorineural hearing loss. In symptomatically infected infants, ganciclovir therapy administered in the neonatal period prevents hearing deterioration. However, preventative therapy of asymptomatic congenital cytomegalovirus disease with ganciclovir is controversial, as side effects such as severe neutropenia may occur during treatment.

The study population consisted of 23 asymptomatic children with congenital cytomegalovirus infection. Twelve children were treated just after diagnosis of cytomegalovirus infection in the newborn period, with ganciclovir 10 mg/kg bodyweight for 21 days. The other 11 children were observed without therapy. Over a four to 10 year follow-up period, we evaluated all the children's hearing status using pure tone audiometry.

All 23 children had normal sensorineural hearing at one year follow up. Five of the 23 children (21.7 per cent) were lost to follow up over the four to 11 year follow-up period. Of the remaining 18 children, sensorineural hearing loss occurred in two (11.1 per cent). Neither child had been treated with ganciclovir in the newborn period. An eight-year-old boy showed bilateral high frequency loss and a 10-year-old girl showed severe unilateral sensorineural hearing loss. In the ganciclovir-treated group (nine children), none showed sensorineural hearing loss. During ganciclovir therapy, moderate neutropenia occurred as a side effect in two out of 12 (16.6 per cent) treated children. Speech and general development were normal in all children.

Asymptomatic congenital cytomegalovirus infection is likely to be a leading cause of sensorineural hearing loss in young children. Intravenous ganciclovir therapy seems to offer a medical option to prevent subsequent sensorineural hearing loss. Further studies including a greater number of children are needed. Cytomegalovirus screening models are mandatory if medical therapy is to be implemented in time.