Role of cytomegalovirus in sensorineural hearing loss of children: a case-control study Tehran, Iran. 
Congenital CMV is the most common cause of nonhereditary sensorineural hearing loss in children.  More than 40% of deafness cases with an unknown cause are due to congenital CMV.  When CMV infection is diagnosed in the first year of life, treatment with gancyclovir is recommended and is associated with diminished occurrence of SNHL.  Previous studies in Tehran showed congenital CMV infection developed in 2.6% of neonates.  To determine the role of cytomegalovirus in sensorineural hearing loss in children by comparing the CMV antibodies quantitatively between SNHL and controls.  This case-control study was done in the ENT Department of Hazrat Rasoul Akram Hospital in Tehran (2002-2003).  This study was carried out based on diagnostic parameters (AAO criteria) for SNHL and a healthy control.  We compared the specific cytomegalovirus antibodies (IgM and IgG measured by ELISA method) in 95 blood samples of infants with SNHL (mean age=35+/-30 months) and 63 healthy matched infants (mean age=38.7+/-27.3 months) as controls.  59.6% of cases were male; 40.4% were female.  Acute and previous immunity to cytomegalovirus (IgM and IgG) was found in 34.7% and 72.6% of SNHL children, acute infection detected in 3.5% of controls, previous immunity (IgG) detected in 94.7% of them.  Acute CMV infection was higher in the cases (P-value=0.000) but previous immunity (CMV-IgG) was higher in the controls (P-value=0.001).  Mean age of cases with acute infection (CMV-IgM) was 40 months and for previous immunity (CMV-IgG) was 35 months in SNHL cases and 40 months in controls, respectively.  Cytomegalovirus is one of the most common infectious agents in SNHL children compared to the healthy children.  Probably both congenital and acquired CMV can induce progressive hearing loss in our cases.  We prefer at least in our country to consider seropositive (CMV-IgM) SNHL children (less than 1 year old) as congenital form.  But we are not able to differentiate the congenital from the acquired infection in seropositive (CMV-IgM) SNHL children after first year of life.  It should be subjected to randomized controlled trial for treatment of acquired type of CMV infection in SNHL children with ganciclovir.