Cytomegalovirus and Toxoplasma Gondii: Common Causes of Profound Sensori Neural Hearing Loss in Children with Cochlear Implant Surgery in a Highly Immune Population: Tehran; Iran

Iranian population is highly immune from T.Gondii and CMV infection.

To determine the immunity to T.Gondii and CMV in children with the cochlear implant surgery accompanied with the profound Idiopathic type of SNHL

We studied 45 cases with the cochlear implant surgery (Idiopathic profound SNHL) and 30 controls with the normal OAEs in a cross-sectional study in Rasoul Akram Hospital in Tehran (2010 -2012). Blood samples (2 ml) were centrifuged and were kept frozen at -20°C. Sera searched for the specific antibodies against CMV and T.Gondii. The enzyme-linked immunosorbent assay (ELISA; BioChem Immune System) was calculated qualitatively. (P value< 0.05)

Range of age in cases with profound SNHL (<95 dB) was 6 months- to-14 years; mean=3.4+3.16 y; Idiopathic type of SNHL children diagnosed in 45 cases were younger than cases with non-Idiopathic SNHL (mean age=20 months; PV=0.05). Positive T.Gondii - IgM was found in 8 /45 (17.7%) and also one of these cases (2.2%) had positive T.Gondii –IgG test. Positive CMV- IgM & IgG were determined in 23% and 51% of cases, respectively. Positive T.Gondii –IgG was observed in 60% (18/30) of controls but none of them had positive T.Gondii – IgM. Positive CMV- IgM & IgG in controls was 3.3% and 90%, respectively.

CMV infection is one of the most common infections found in profound idiopathic SNHL children especially in younger cases (< 2 years) even in highly immune Iranian populations. Probably, T.Gondii infection has a relative role in younger cases with profound SNHL but a higher role in mild to moderate SNHL in our pediatric population. Most of the T.Gondii infected SNHL cases never require cochlear implant surgery.

In future, a cohort study for prenatal diagnosis of the intrauterine infection and the role of infection in producing SNHLwould be very helpful. It has been recommended to search the specific antibodies against these two common infections in all types of SNHL in pediatric groups which are treatable especially in younger cases (<2 year).