ANN ARBOR —
By testing the hearing of newborns whose health problems put them at special risk of hearing loss, doctors at the University of Michigan Health System are catching and addressing infant hearing problems far better and less expensively than the national norm, according to a new report on the pioneering program.
The successful early detection of immediate or delayed damage—found in 6.4 percent of the infants studied—allowed babies to be fitted with hearing aids before their development was affected. After 10 years of testing at the U-M involving more than 2,100 babies, the encouraging results are being published in the July issue of the American Journal of Otology.
“This program puts limited testing resources where they are most needed and can do the most good: among those babies most in danger of losing some or all of their hearing,” says co-author Paul Kileny, director of Audiology and Electrophysiology for the U-M and professor in the Department of Otolaryngology. “Still, we cannot overlook the importance of training pediatricians and new parents to detect early signs of hearing loss in healthy babies.”
The babies were all treated in the neonatal intensive care unit of the U-M’s C.S. Mott Children’s Hospital. Under the U-M’s guidelines, all babies who are born with or develop one or more of 10 risk factors for hearing loss are given a sensitive hearing test within a few days of birth.
Those who fail—or who are at risk of delayed-onset problems but who pass the initial test—are tested again two to four weeks later. For those who pass, the U-M sends the parents a questionnaire about hearing-loss symptoms when their babies are seven to nine months old.
Risk factors for infant hearing loss include low birth weight; family history of childhood deafness; infection with a virus such as herpes; use of an antibiotic, respirator or heart-lung machine after birth; and abnormalities of the head, face or neck. The test, called auditory brainstem response or ABR, plays clicks into the ear and measures the response through electrodes on the head.
The study showed that 137 babies, or 6.4 percent of the entire group, had hearing loss in one or both ears. Nearly half of them had moderately severe to profound hearing loss. By contrast, studies have shown that less than 0.4 percent of healthy babies have hearing loss.
“One of the key findings with this study is the ability of ABR to spot hearing deficiencies early, allowing rapid management of the condition,” Kileny explains. “Now that cochlear implants are available for infants as young as 18 months, it’s increasingly important to make sure that babies with hearing problems are treated soon after their condition develops.”
Children whose hearing problems go undetected and untreated can suffer developmental delays, sometimes insurmountable. Nationally, the average age at which hearing problems are identified is 2 or 3, long after the child should have begun learning language and speech. Children diagnosed that late must play catch-up with others their age, through special educational and therapeutic efforts.
Still, the incidence of hearing problems in most children is extremely rare, as shown by studies stretching back to the introduction of ABR in the late 1970s. In the U-M study of at-risk infants, the cost to find each hearing-impaired baby was $3,000. Screening the entire population of healthy babies, as recommended by the National Institutes of Health (NIH) in 1993, would make the cost per case identification substantially higher.
So, Kileny suggests that in the face of intense health care cost pressures and shorter hospital stays for healthy babies, sensitive hearing tests shortly after birth may be best reserved for only at-risk newborns.
But, he cautions, this is only true if newborns’ doctors are trained to recognize risk factors and refer at-risk babies for testing—and if pediatricians and parents are educated about the early outward symptoms of both immediate and delayed infant hearing problems.
Then, he says, infants can be assessed at their one- and two-month checkups, where doctors and parents can compare notes about hearing indicators and refer those babies in whom they suspect hearing loss for specialized diagnosis and treatment.
The issue of hearing tests for newborns is far from settled. So, Kileny and his colleagues are now embarking on a new study of 3,000 healthy babies to compare the effectiveness of hearing tests with that of parent and physician education. The infants will come from the U-M and other local hospitals with large numbers of births.
Funded by the Carls Foundation, the study will also include babies who face hearing-loss risk factors. Both the ABR test and a newer, faster approach called an otoacoustic emission test will be given, allowing the sensitivity and objectivity of the two tests to be compared.
All tested newborns, healthy and at-risk, who fail the initial test will be tested again at the age of 6 weeks to assess their hearing ability even more accurately. Parents whose babies are not tested will be given informational materials and sent a follow-up checklist when their babies are 3 to 4 months old. Their pediatricians will also be given information, and told where to refer babies for testing if they feel it is needed.
No matter what the outcome of that upcoming study, and of an NIH study now being completed, Kileny emphasizes education. “The most important lesson for doctors and parents alike is that ongoing monitoring is essential,” he says. “No test is 100 percent accurate, and no one moment is the right time to catch all problems early enough to correct them completely. It’s up to all of us to keep vigil over children’s hearing as they grow, and to act quickly if we suspect a problem.”

Health SystemAmerican Journal of OtologyDepartment of OtolaryngologyC.S. Mott Children’s HospitalNational Institutes of Health