Early Warning

Testing young children for hearing disabilities is not a new idea. At two hospitals in Israel, routine screening of newborns in neonatal units has resulted in the speedy diagnosis of complete or partial deafness in infants. This means that children only three months old can be fitted with hearing aids when their cognitive development stands most to gain.

Although newborn screening is not included of free health services, Sheba Hospital at Tel Hashomer and Hadassah-University Hospital in Ein Kerem (Jerusalem) have already introduced the program, in step with major hospitals in the US and Europe. Screening at Sheba was initiated some two years ago, while the Hadassah project made possible by an annual donation of about $50,000 began in October 1999, and is run with the help of young women performing their National Service.

"It is well known that a fetus already can hear during the third trimester of pregnancy, and at birth the neonate hears the sounds of the surrounding world," says Haya Levi, a speech and hearing clinician, and the director of Hadassahs Speech and Hearing Center. "Hearing is essential for the normal development of speech and language. But unfortunately, one or two out of every 1,000 newborns suffer from severe to profound sensory-neural hearing loss, which can greatly delay the onset of speech, as well as the development of language and social skills."

Israeli babies are routinely taken by their parents to tipat halav (baby clinics) for regular check-ups, and between the ages of seven to nine months they are examined for hearing problems. The nurse at the clinic speaks, rings bells, shakes a rattle, stirs a spoon in a cup, and crinkles cellophane behind the babys back, noting each time whether the baby turns towards the source of the noise. This important test has resulted in over half of all affected children being diagnosed and treated by the age of 18 months. "The screening done there is vital in detecting progressive hearing loss and identifying children for whom the cause of the hearing problem lies in the auditory pathways," Levi notes. But audiology specialists agree that if hearing loss is detected before the age of three months, and experts intervene by the age of six months, the child will enjoy the optimal benefit.

Miriam Geal-Dor, who coordinates Levis newborn screening, explains that the "Transient Evoked Otoacoustic Emission Test" can be conducted while the baby is lying down, as long as he or she is not crying. The test is not invasive or painful; it involves inserting a tiny earpiece into each of the babys ears, one after the other. The newborns responses to auditory stimuli are registered, and the entire test takes just five minutes. Babies born prematurely undergo the test the day before they are sent home.

Less than five percent of the 3,000 babies who have been screened so far have failed the test, most of them in one ear and half as many in both ears. But, notes Levi, that does not mean that all of them are hearing disabled. "The most common cause for failure is birth-related debris in the outer ear or fluids in the middle ear, both of which clear within a very short time."

Babies who fail the initial screening test undergo a second one before they are discharged from the hospital. Those who fail a second time are invited back for further examination, and if found to suffer from hearing disabilities, are fitted with a suitable hearing aid. However, if there is no significant improvement by the age of 18 months, the child may be fitted with a cochlear implant, a hearing aid used in patients whose microscopic hair cells inside the cochlea of the inner ear have been seriously damaged or depleted. Such deafness can be caused by the mothers exposure to rubella (German measles virus) or cytomegalovirus during pregnancy, by premature birth, or by genetic problems.

A total of 68 profoundly deaf young children have undergone cochlear implant surgery at Hadassah during the past five years. In a three- to five-hour operation, surgeons insert a spiral electrode some 24 millimeters behind the outer ear into the natural curve of the cochlea. A thin wire emerges from the skull and is attached to a speech microprocessor that can be carried in a pocket or worn on a belt like a beeper. Some new units are so small that they can even be worn over the earlobe like a hearing aid. Levi, together with her staff of 12 other speech and hearing clinicians, fit the children with the external part of the device and train them to use it. The cost of the implant $20,000 is completely covered by their health funds. "Two of our first children to receive implants can already sing!" Levi comments. "The work is very satisfying."