title: Hearing loss and congenital CMV infection: a systematic review.
abstract: OBJECTIVE
  Hearing loss caused by congenital cytomegalovirus (cCMV) infection was first observed in 1964. Today cCMV is the most common cause of nonhereditary sensorineural hearing loss in childhood. Our objective was to provide an overview of the prevalence of cCMV-related hearing loss, to better define the nature of cCMV-associated hearing loss, and to investigate the importance of cCMV infection in hearing-impaired children.
  
  
  METHODS
  Two reviewers independently used Medline and manual searches of references from eligible studies and review articles to select cohort studies on children with cCMV infection with audiological follow-up and extracted data on population characteristics and hearing outcomes.
  
  
  RESULTS
  Thirty-seven studies were included: 10 population-based natural history studies, 14 longitudinal cohort studies, and 13 retrospective studies. The prevalence of cCMV in developed countries is 0.58% (95% confidence interval, 0.41-0.79). Among these newborns 12.6% (95% confidence interval, 10.2-16.5) will experience hearing loss: 1 out of 3 symptomatic children and 1 out of 10 asymptomatic children. Among symptomatic children, the majority have bilateral loss; among asymptomatic children, unilateral loss predominates. In both groups the hearing loss is mainly severe to profound. Hearing loss can have a delayed onset, and it is unstable, with fluctuations and progression. Among hearing-impaired children, cCMV is the causative agent in 10% to 20%. Despite strict selection criteria, some heterogeneity was found between selected studies.
  
  
  CONCLUSIONS
  This systematic review underscores the importance of cCMV as a cause of sensorineural hearing loss in childhood.
authors.affiliation: Department of Otorhinolaryngology and julie.goderis@ugent.be.
authors.forename: Julie
authors.initials: J
authors.lastname: Goderis
authors.affiliation: Department of Otorhinolaryngology and.
authors.forename: Els
authors.initials: E
authors.lastname: De Leenheer
authors.affiliation: Neonatal ICU, University Hospital Ghent, Ghent, Belgium.
authors.forename: Koenraad
authors.initials: K
authors.lastname: Smets
authors.affiliation: Department of Otorhinolaryngology and.
authors.forename: Helen
authors.initials: H
authors.lastname: Van Hoecke
authors.affiliation: Neonatal ICU, University Hospital Ghent, Ghent, Belgium.
authors.forename: Annelies
authors.initials: A
authors.lastname: Keymeulen
authors.affiliation: Department of Otorhinolaryngology and.
authors.forename: Ingeborg
authors.initials: I
authors.lastname: Dhooge
mesh_terms: D000818:Animals; D015331:Cohort Studies; D003586:Cytomegalovirus Infections / Q000175:diagnosis* / Q000453:epidemiology*; D006319:Hearing Loss, Sensorineural / Q000175:diagnosis* / Q000453:epidemiology*; D006801:Humans; D008137:Longitudinal Studies; D012189:Retrospective Studies
keywords: auditory; congenital infection; cytomegalovirus; hearing; prevalence; symptomatic infection; systematic review