The researchers estimated that hearing loss affects 9 to 15 per cent of HIV-infected children and 5 to 8 per cent of children who did not have HIV at birth but whose mothers had HIV infection during pregnancy. Study participants ranged from 7 to 16 years old.
The researchers defined hearing loss as the level at which sounds could be detected, when averaged over four frequencies important for speech understanding (500, 1000, 2000, and 4000 Hertz), that was 20 decibels or higher than the normal hearing level for adolescents or young adults in either ear.
"Children exposed to HIV before birth are at higher risk for hearing difficulty, and it is important for them ― and the health providers who care for them ― to be aware of this," said George K. Siberry who leads the research network.
Compared to national averages for other children their age, children with HIV infection were about 200 to 300 per cent more likely to have a hearing loss. Children whose mothers had HIV during pregnancy but who themselves were born without HIV were 20 per cent more likely than to have hearing loss.
"If parents and teachers know the child has a hearing problem, then they may take measures to compensate in various communication settings, such as placement in the front of the classroom or avoiding noisy settings," explained Howard Hoffman.
To determine the types of hearing loss the children experienced, the researchers conducted these evaluations:
• Physical examination of the ear canal
• Evaluation of the middle ear function, how sound vibrations are transmitted through the middle ear bones
• Responses to tones presented over earphones
Hearing loss may occur from damage to the bones and structures in the ear canal and inner ear, or from damage to the nerves leading to the brain.
MEDICA.de; Source: National Institutes of Health