Hearing tresholds in children with a congenital CMV infection: a prospective study.

Objective: Hearing treasholds in children with a congenital cytomegalovirus (cCMV) are not always stable. Children can develop late onset hearing loss, fluctuations, progression (worsening) and improvement of hearing loss. Knowledge about these characteristics is important to understand why long term follow up in these children is mandatory.
Methods: We prospectively follow a cohort of 154 children wicht cCMV infection, 68 of which met the inclusion criteria of at least 3 hearing evaluations over a period of at least 18 months in the absence of other risk factors for hearing loss. In those 68 children we evaluated the occurence of ustable hearing tresholds: late onset hearing loss, fluctuations, progression and improvement of hearing loss.
Results: ustable hearing tresholds were observed in 29.4 % of children with cCMV infection of which 19.2 % were found in the group of children with ultimately normal hearing and in 62.5 % of children with sensorineural hearing loss (SNHL) (p= 0.0027). Fluctuations occurred in 16.2 %. Late onset hearing loss occurred in 4.3 % of children with a normal hearing at birth. In children with SNHL, progression or worsening of hearing tresholds occured in 27.3 % and improvement of tresholds in 40.9 %. Important changes in tresholds only occurred in 13.2 % of children and predominantly in children who finally develop SNHL.
Conclusions: Unstable hearing tresholds are frequently found in children with cCMV infection and occur not only in children who develop hearing losses but also in children who have a normal hearing at the last visit. Important changes in hearing tresholds of >30 dB are more frequently seen in children who ultimately will develop SNHL.