Mr. and Mrs. X. were pleased to see that their 2 month old daughter had grown so much since her last visit. As this was her regular "well-check", we discussed her appetite, sleep patterns and bowel habits before plotting her growth on the growth chart.
Then I said, " Before I examine her, I would like to know what she is doing developmentally." Dad sort of snickered and said, "There’s not a lot that she does except eat, sleep and poop." Then I asked about things that most normal two months usually do. This includes following or tracking with their eyes, having a social smile, cooing, demonstrating better head and neck control, and responding to noises or voices (hearing).
Both Mr. and Mrs. X. were amazed to think that their little baby could do all of these things at just two months of age...but there was an uncomfortable pause as I started to do the physical exam. "Just how do we know if she really hears?" mom asked in an unsettled voice. I told her that she should startle to loud noises, turn to voices or familiar sounds, or even recognize mom or dad’s voice. With this, Mrs. X.’s demeanor changed and she became serious and obviously preoccupied. "I’m not sure that she does these things," she went on. I looked at dad and Mr. X. shrugged his shoulders as if to concede that he too, wasn’t really sure. Then Mrs. X. asked, "Is it common to see infants that don’t hear? How do you test their hearing anyway?" she continued.
Hearing loss is one of the more common congenital abnormalities that is seen in newborns, occurring in around 1-3/1000 live births. About 20% of these affected infants have profound hearing loss. Certain infants are at high risk for hearing loss and these include babies:
Certainly these babies should be tested at the earliest and most convenient time...at least by 3 months of age. Most neonatal intensive care units screen ALL the babies that have been admitted to their unit. How do you actually test a baby's hearing?
The best way is through the use of a brain stem auditory evoked response (BSAER). This is a machine that has 2-3 recording electrodes (just like a brainwave EEG) that are taped to the baby's head just over the hearing center. Then a clicking sound is generated from the machine that delivers a predetermined number of decibels of sound. If the hearing is fully intact, a "blip" should be recorded from the electrodes. This is an accurate test, and does not require the cooperation of the infant.
Some in the health community have called for the universal hearing screening of ALL newborns just as is done for phenylketonuria (PKU), galactosemia, hypothyroidism and sickle cell disease. They argue that the incidence of congenital hearing loss is twenty times greater than that of PKU. It is twice as common as PKU, galactosemia, hypothyroidism and sickle cell disease combined.
In 1999, the American Academy of Pediatrics endorsed the universal screening of newborns, and that same year a bill was introduced into Congress which recognized universal screening on a national level and recommended funding to assist states in establishing such programs. It also recommended funding for the Center for Disease Control and the NIDCD to track and manage those newborns that are identified. To date however, only 22 states have passed newborn and infant hearing screening legislation. Funding for such a venture is the main stumbling block.
Since routine screening is not a reality in most states, the parents and the physicians must be vigilant and diligent to the infant's development at the scheduled well checks (2, 4, 6, 9 and 12 months). If there is ANY question about a baby's ability to hear, a BASER should be performed. What are some of the things a parent should look for?
Between 1-4 months, a baby should startle to loud noises, quiet to mother’s voice, and momentarily cease activity when voices are presented at a conversational level. Between 5-6 months, a baby should correctly lateralize sound when presented in a horizontal plane, and should reciprocally vocalize with an adult. Between 7-12 months, a baby should be able to lateralize sound in any plane, and should be able to respond to their name even if spoken quietly.
Clearly the goal should be identification of hearing loss at the earliest age possible so that appropriate treatment and intervention can be established. In 1988 the average age of identification of a child with hearing loss was 36 months—this is too late. Normal hearing children have developed a great deal of language by this time. The goal for this year is to lower the age of identification to 12 months...a challenging task to say the least.
By the time I finished the well check on Mr. and Mrs.X’s baby, they were convinced that she could not hear...and they were very anxious. There was absolutely no way that I could assure them that she could in fact, hear. To allay their fears (and mine as well), I scheduled her for a BSAER the next day. It was completely normal. No words could describe the relief that the parents felt when they got the news. When I phoned them to give them the results, Mr.X. said, "We hear you loud and clear!"