HealthWatch runs every other week as a regular Gazette feature where medical journalist Evra Taylor Levy and emergency physician Eddy Lang help make sense of sometimes contradictory medical research.
MONTREAL – Imagine the plight of a newborn baby who, at first glance, seems perfectly healthy, yet later as a toddler is discovered to be deaf. And imagine further the heartbreak of parents faced with this difficult situation. This edition of HealthWatch deals with a medical condition that is infrequently discussed yet surprisingly prevalent in Canada: congenital deafness. More specifically, we'll look at whether screening otherwise healthy newborns for hearing problems makes sense.
SCOPE OF THE PROBLEM
Hearing loss is the most common congenital abnormality in newborns. In fact, it occurs more commonly than all of the other conditions for which Canadian newborns are screened. This translates to as many as three of every 1,000 infants being born profoundly deaf, with another three of every 1,000 having significant hearing loss. Most of these newborns are otherwise healthy and, interestingly, most are born to hearing parents.
It is important to note that hearing loss is not usually noticed by parents in the early months of life, nor can it be detected in a doctor's office during routine checkups. As a result, severe deafness is usually diagnosed when children are between 18 and 30 months old, with less significant hearing loss being identified much later. At roughly age 3, if untreated, children experience delays in the learning of language, and fail to develop key sections of the brain that relate to communication.
THE HEARING-SPEAKING LINK
The ability to hear plays a crucial role in the formation of early language skills. The first few months of life represent a narrow window of opportunity for the evolution of these abilities, reflecting the clear correlation between literacy and hearing/speech. A child needs to hear to speak, and a child who hears and speaks is more capable of reading and writing. Early intervention with hearing aids and cochlear implants, for example, is thought to be the single most important factor associated with improved language for children with hearing loss.
How do hearing tests work?
While screening can take several forms, the most common method, called the oto-acoustic emission test, involves sending a sound into the newborn's ear through a small probe.
The sound stimulates the cochlea to vibrate, creating an echo that is picked up by the probe. The absence of an echo indicates a hearing loss. The test is non-invasive, painless, takes about 10 to 15 minutes to perform, and costs roughly $35 per child.
Who should be screened?
Babies born prematurely and who require care in a neonatal intensive care unit are at a high risk of congenital hearing loss. As a result, screening this group, and others with risk factors, is uniformly accepted as a standard of care. The debate is centred on whether or not all newborns should undergo hearing screening as part of a universal program.PAGEBREAK
F. Declau et al. Etiologic and audiologic evaluations after universal neonatal hearing screening: analysis of 170 referred neonates. Pediatrics, June 2008.
The study looked at the impact of the universal screening program developed in Belgium in 1998 that, by 2006, had screened more than 87,000 babies. The authors report the findings in 170 infants who were referred to their specialized hearing clinic after failing a screening test.
What did the study show?
Most of the newborns (roughly 70 per cent) who were referred to the specialty centre due to a failed screening test through the universal program were in fact confirmed to have hearing loss; the remaining 30 per cent tested as falsely positive and had normal hearing. On average, the babies were just under 2 months of age when their hearing loss was confirmed, which is two or more years earlier than the hearing problem would have been discovered if relying solely on parental concerns or routine checkups.
The other important study finding is that over half of the infants confirmed to have hearing loss had no risk factors and would have been missed in programs that screen only high-risk babies, such as those born prematurely.
Nearly all of the infants identified as a result of the screening program had congenital deafness amenable to early interventions that have been proved to augment hearing and improve language acquisition at an earlier age. Cochlear implants, one of the technologies of most benefit to people with profound hearing loss, have been shown to be cost effective.
What are the pros and cons of universal screening?
While most provinces have a universal screening program, Quebec does not yet have one, although advocates are pushing for its implementation. While the cost of such a program is estimated at $5 million per year, including rehabilitation expenses, the lifelong costs of reduced literacy and specialized programs for the hearing impaired are likely to be far greater. For a variety of reasons, hearing-impaired individuals are less likely to complete a secondary education, have lower rates of literacy, and are more likely to be unemployed as adults.
Universal screening has been adopted in many countries worldwide, which is suggestive of its overall benefit. While data on the language outcomes of children who are provided with early intervention is limited, preliminary studies indicate that the majority of these children can be expected to enter the regular school system.
What should parents do?
In mid-May, Quebec's public health agency - the Institut national de santé publique du Québec - posted a detailed report on its website strongly supporting the creation of a universal hearing screening program in this province.
While the health ministry considers these recommendations, and while future research will more precisely measure the degree of improvement in language skills, parents would be on very solid ground to seek out screening for their newborn.
HealthWatch acknowledges the input of Hema Patel, pediatrician at the Montreal Children's Hospital and acting co-chair of the Coalition for Universal Newborn Hearing Screening.
The material provided in HealthWatch is designed for general educational purposes only and does not pertain to individual cases. The information included should not replace necessary medical consultations with your own doctor or medical professional.
Canadian Academy of Audiology
Alberta universal hearing screening program for newborns
Institut national de santé publique du Québec’s report on screening newborns
The Hearing Foundation of Canada