Deafness in Newborn goes undetected. Can your baby hear you?

May 26, 2010 - PRLog -- The birth of a healthy baby is a miracle. The child emerges with ten fingers and toes, perfectly formed to touch and kick in a big, new world. Nose and taste buds yearn for the first meeting with mother’s nutritious milk. A baby even opens its eyes trying to focus on the blurry faces of parents looming close, cooing their hellos and declarations of love.

“Wait,” thinks one baby out of 1,000. “Something is missing. You’re cooing and kissing but I can’t hear a thing!?” Indeed, no adults seem to notice that in spite of all this activity, all is silent to the baby.

After the birth, our baby is pulled out of its mother’s warm and protective arms into the hands of a pediatrician for examination. Seemingly, with a fine tooth comb, he makes sure that all is complete and well, and that there are no defects or deficiencies to be addressed before the baby leaves the hospital. The physician looks into every opening, fold and crevice, tests the limb joints and reflexes, listens for the heartbeat and breathing, and almost always gives the delighted parents the clean bill of health, congratulations and the measuring tape with the baby’s length noted.

Why was this baby, and nearly 50% of all babies with later-discovered hearing loss, sent home from the hospital after delivery with undetected hearing loss? The reason is that hearing loss detection tests were not routinely performed on infants until recently, when Government sponsored universal screening programs were initiated for newborns.


Why is it important to identify infants with hearing loss?
The ability to detect hearing problems in newborn infants is crucial. Studies have shown that being able to process auditory information early in life is crucial for later development of reading and spoken language skills. Hearing loss is associated with social and emotional developmental lags in children as well as poor academic achievement.

What is the incidence of congenital hearing loss?
Congenital hearing loss can be found in two to three infants per 1,000 live births. That means that there are approximately 5,000 babies born in the United States each year with bilateral permanent hearing loss.

How do you define hearing loss in newborns?
Newborns are checked for moderate to severe bilateral permanent hearing loss. Current testing after birth does not pick up loss that is progressive or acquired later in life. The current testing programs detect hearing losses at a threshold of 30–40 dB in the frequency important for speech recognition (500–4,000 Hz)

What are the characteristics of children that are most likely to have hearing loss?
Babies who were determined to be at high risk for hearing loss include children that were admitted to the neonatal intensive care unit for more than 2 days, (1–2 cases of hearing loss for every 200 babies), premature infants, children with craniofacial anomalies, family history of hearing disorders, children whose mothers developed infections in utero, and children who are born with certain syndromes. However, it was found that close to half of all the children not in the high risk group were missed. Therefore, about 50% of all children with hearing problems were sent home from the hospital with undetected hearing loss.

What are the current state requirements to have children checked prior to leaving the hospital?
Currently in all 50 states, Guam, and the District of Columbia regulations direct testing of all children for hearing loss before leaving the hospital. All states and US territories have Early Hearing Detection and Intervention (EHDI) programs funded by the Federal Government which delineate the screening protocols, follow-up care and collection of data. This data collection has been initiated only since the 1990’s. The US Department of Health and Human Services now has clear guidelines which include a universal protocol that screening should occur before 1 month of age, follow-up for infants not passing the test no later than 3 months of age and follow-up intervention prior to 6 months of age for infants identified with hearing loss. Due to initiation of these programs, the number of infants screened for hearing loss increased from 46.5% in 1999 to 97% in 2007.

What are some of the causes of hearing loss in infants?
Hearing loss can be divided into 4 categories:

1.Central
This is due to deafness caused by problems along the auditory pathway to the brain or in the brain.
High levels of bilirubin (breakdown product of blood cells—often causing jaundice in the newborn.)
Hypoxia (low oxygen levels)
Intraventricular hemorrhage (bleeding within the brain.)
2.Conductive
This is caused by problems with the outer ear, middle ear, the tympanic membrane, or the bones of the ear and affects all frequencies equally. This may also be due to congenital cholesteatoma (growth in the middle ear.)
3.Sensorineural
This is caused by problems in the inner ear or auditory nerve. About 50% of these are due to various genetic diseases and syndromes (Alport’s Syndrome, Turner’s, Usher’s, Waardenburg’s syndrome). Scientists have now mapped genes that cause hereditary hearing loss, in families. In 20–30% of cases, sensorineural defects can also be due to infectious causes such as cytomegalovirus ( most common), group B strep infections, herpesvirus, rubella, toxoplasmosis, and syphilis. Mothers can acquire these infections during pregnancy and pass it to the fetus in utero. Children can show no signs at birth but go on to develop deafness later on in life. Unknown causes (idiopathic) and anatomic causes are also in this category.
4.Mixed
This includes a combination of the above etiologies.

What are the most common tests used for screening?
There are 2 infant tests available called the AABR and the TEOAE. Both diagnose sensorineural hearing loss in newborns. There is no evidence that one test is superior to the other to date, although some studies have shown a lower rate of false positives with AABR. Children with positive testing are referred for further testing and details are obtained about genetic and family history.

1.Automated brainstem response (AABR)
This checks the auditory pathway from the outside ear to the lower brainstem. Infants have their ears covered with earphones that emit a series of clicks. Electrodes on the infants forehead and neck measure brain wave activity in response to the clicks which is then fed into a computer that assess the brain wave activity.
2.Transient evoked otoacoustic emissions (TEOAE)
This test evaluates the function of the cochlea by placing a small microphone in the external ear canal and testing the echo responses to a series of clicks which is then placed thru a computer and compared to the standard.
With any kind of testing, the important issue is the false positive and false negative rates. Universal newborn screening has a high number of false positive rates, mostly due to motion artifacts. Other causes of false positives can be due to fluid in the ear or ear infections. False positive rates can be as high as 30% with a one step test, to less than 1% if a child is tested twice. If a child fails the test twice, an ear, nose, and throat referral is directed by the pediatrician.

What are the future goals to improve the medical care of infants with hearing loss?
Future goals include devising a system for providing better follow-up care on children who do not pass the initial screening and for screening children that fall below the threshold and have milder forms of hearing loss or late onset and progressive forms of hearing loss that can be missed. Also, ensuring that children with documented disorders are enrolled in intervention programs is critical. Children that have risk factors should not only be screened at birth but again throughout childhood.

Recommendations by the Joint Committee on Infant hearing recommends testing every 6 months before 3 years of age in high risk children. More Federal programs are being initiated.

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Since the beginning of her Obstetrics and Gynecology practice in 1982, Dr. Michele Brown has delivered more than 3,000 babies. She has her medical training to guide her in the development of Beaute de Maman's unique health and beauty products. Dr. Brown has a busy obstetrical practice in Stamford, Connecticut. As a clinical attending, she actively teaches residents from Stamford Hospital and medical students from Columbia Presbyterian Hospital in New York. Dr. Brown is a board-certified member of the American College of Obstetrics and Gynecology, a member of the American Medical Association, the Fairfield County Medical Association, Yale Obstetrical and Gynecological Society and the Women's Medical Association of Fairfield County.

Please visit http://www.beautedemaman.com

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