Hearing outcome in congenitally CMV infected children in Finland - Results from follow-up after three years age.

Objectives: Cytomegalovirus (CMV) is the most common congenital infection affecting about 0.6% of all newborns in developed countries. Vertical transmission to fetus can take place either after maternal primary or non-primary CMV infection during pregnancy. It is the most common infectious agent for sensorineural hearing loss (SNHL) in young children. The hearing loss after congenital CMV (cCMV) may be present at birth, or may develop after months or even years. In this study, we evaluated hearing outcome at 3-4 years of age in children (n 32) with cCMV identified in universal saliva CMV-PCR-based screening.

Methods: Study population consisted of mainly asymptomatic children (median age 3.1 years) with cCMV identified in newborn CMV screening. The type of maternal CMV infection (primary or non-primary) was determined by analyzing CMV antibodies (IgM, IgG and IgG avidity) from preserved maternal serum samples drawn in the end of first trimester of pregnancy. Hearing was evaluated with pure tone audiometry (PTA), or transient-evoked otoacoustic emission (TEOAE) and sound field audiometry (SF).

Results: Unilateral hearing loss occurred in 5/32 (16%) of the children with cCMV. None of the subjects in our cohort had bilateral hearing loss. Hearing loss occurred in 3/15 (20%) of children who were born to mothers with non-primary CMV infection during pregnancy, and in 2/10 (20%) of children whose mother had had a primary CMV infection during the 2-3 trimester. None of the additional 6 children, whose mother had primary infection in the first trimester, had hearing loss by age of 3-4 years. Two children with normal hearing at 1 years age had developed unilateral hearing loss by the age of three.

Conclusions: Unilateral hearing loss was relatively common among the mainly asymptomatic children with cCMV identified in screening. Long-term follow up of children with cCMV is essential to identify the children with late-onset hearing loss.