Children exposed to HIV in the womb at increased risk for hearing loss
NIH study shows risk greater for HIV-infected children than for uninfected peers
June 20, 2012 - Children exposed to HIV in the womb may be more likely to experience hearing loss by age
16 than are their unexposed peers, according to scientists in a National Institutes of Health research network.
The researchers estimated that hearing loss affects 9 to 15 percent of HIV-infected children and 5 to 8 percent 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's important for them?and the
health providers who care for them?to be aware of this," said George K. Siberry, M.D., of the Pediatric, Adolescent, and Maternal
AIDS Branch of the Eunice Kennedy Shriver National Institute of Child Health and Human Development (NICHD), the NIH institute
that leads the research network.
The study was published online in The Pediatric Infectious Disease Journal.
Compared to national averages for other children their age, children with HIV infection were about 200 to 300 percent more
likely to have a hearing loss. Children whose mothers had HIV during pregnancy but who themselves were born without HIV were 20 percent
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, M.A., director of the Epidemiology and Statistics Program at the National Institute on
Deafness and Other Communication Disorders (NIDCD), which provides funding to the network for studies related to hearing and language.
Even a mild hearing loss in children can delay the acquisition of language skills. More severe hearing loss may require the
use of assistive devices, such as a hearing aid. Information on hearing and
deafness is available from NIDCD.
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.
First author Peter Torre III, Ph.D., of San Diego State University, led the study with Hoffman, Siberry and six other
coauthors. Collaborators were from the Harvard School of Public Health, Boston; the University of Kansas, Lawrence; and Tulane
University School of Medicine, New Orleans.
The research was conducted as part of the Pediatric HIV/AIDS Cohort Study network,
led by NICHD in cooperation with and with cofounding from NIDCD and several other NIH institutes, including: the National Institute on
Drug Abuse, the National Institute of Allergy and Infectious Diseases, the National Institute of Mental Health, the National Institute
of Neurological Disorders and Stroke, the National Heart Lung and Blood Institute, and the National Institute on Alcohol Abuse and
Alcoholism.
More than 200 children and teenagers participated. All had been exposed to HIV before birth, and about 60 percent were
HIV-positive at the time of the study. Researchers conducted hearing tests on the children if their parents or caregivers had
reported hearing problems, they had low scores on a standard test of language or their health care providers detected hearing
problems during standard hearing screenings.
The researchers classified participants who could not hear tones below a certain volume as having hearing loss with
difficulties in quiet and noisy settings. The researchers documented a greater proportion of hearing loss cases among HIV-positive
children and found that those who had developed AIDS at any point were even more likely to have hearing loss-even if the disease
was under control at the time of the study.
Earlier studies have found that children with HIV are susceptible to middle ear infections. Repeated middle ear
infections can cause hearing loss. However, in 60 percent of cases in the study, hearing loss was the result of problems with
the transmission of sound from the nerves of the ear to the brain, rather than to damage in the middle ear resulting from
ear infections.
"Although ear infections are more common among children with HIV, these do not appear to be the reason their hearing
is more likely to be compromised," said Torre. 011012-HIV-treatement-vitamin-D.cfm">previously found that vitamin D supplements
might help protect the bones of people taking the anti-HIV drug tenofovir.
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About the Eunice Kennedy Shriver National Institute of Child Health and Human Development (NICHD) :
The NICHD sponsors research on development, before and after birth; maternal, child, and family health; reproductive biology and
population issues; and medical rehabilitation. For more information, visit the Institute's website
at http://www.nichd.nih.gov/ .
About the National Institutes of Health (NIH) :
NIH, the nation's medical research agency, includes 27 Institutes and Centers and is a component of the U.S. Department of Health
and Human Services. NIH is the primary federal agency conducting and supporting basic, clinical, and translational medical research, and
is investigating the causes, treatments, and cures for both common and rare diseases. For more information about NIH and its
programs, visit http://www.nih.gov .
NIH...Turning Discovery into Health
Source: National Institutes of Health
http://www.nichd.nih.gov/news/releases/062012-HIV-hearing-loss.cfm
"Reproduced with permission - National Native HIV/AIDS Awareness Day (NNHAAD)"
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