It's just as important to identify and treat newborns and young children with deafness in one ear, or long term prospects for hearing recovery may be diminished, according to a new research review.
Leaving one-sided deafness untreated leads to reorganization of developing hearing pathways in the brain, and has been tied to poorer language development and educational outcomes, the authors write in Paediatrics.
"Traditionally, asymmetric deafness in childhood, particularly when only one ear is affected, has been overlooked or dismissed as a concern because the children have had some access to sound," said lead author Karen Gordon of Archie's Cochlear Implant Laboratory at The Hospital for Sick Children in Toronto, Canada.
"The problem is that children with asymmetric hearing still have a hearing loss," Gordon said by email. "Without normal hearing from both ears, they experience deficits locating sounds around them."
Lack of knowledge on treatment options
A child with a hearing loss in one ear may have difficulty hearing what her mother is saying when there are other noises in the room or other people speaking at the same time, she said.
Still, parents can be reluctant to treat asymmetrical deafness in young children.
"One of the main issues is lack of information," said Dayse Tavora-Vieira of the University of Western Australia in West Perth, who was not part of the new review. "The implications of unilateral hearing loss/deafness have been historically underestimated by professionals and this has reflected on how they counsel parents."
Also, the children may not show a handicap until educational, social and emotional concerns become clear later in life, she told Reuters Health by email.
In addition to delayed speech and language development, these children are at risk of poor academic performance, usually with poorer vocabulary and simpler sentence structure than their normal-hearing peers, Tavora-Vieira said.
Gordon and her colleagues reviewed research from neuroscience, audiology and clinical settings "that points to the existence of an impairment of the central representation of the poorer hearing ear if developmental asymmetric hearing is left untreated for years," they write.
"We suggest that asymmetric hearing in children be reduced by providing appropriate auditory prostheses in each ear with limited delay," Gordon told Reuters Health. "The type of auditory prosthesis will depend on the degree and type of hearing loss."
Two in every thousand babies affected
Almost two in every 1,000 babies have some form of deafness discovered by early life screening, according to a 2009 Centres for Disease Control and Prevention survey.
Currently, children with hearing loss can be treated with a cochlear implant, for profound deafness, a hearing aid, a bone anchored hearing aid or a personal listening device like a radio-enabled earbud in the hearing ear. For the last, a speaking source, like a teacher, speaks into a microphone, which transmits sound by FM signal to the earbud.
Costs can vary from less than $1,000 to several thousand dollars, depending on the treatment, Tavora-Vieira said. Cochlear implants are the most expensive and in many countries are still not reimbursed. Bone conduction implants are also expensive and not well accepted by children, she said.
Treatment and therapy should begin as early in life as possible, Tavora-Vieira said.
"The developing auditory system appears to change quickly when one ear is deaf, resulting in an abnormal preference for the hearing ear," she said.
"Appropriate recommendations can be made by otolaryngologists and audiologists," Gordon said.
Parents should be critical of a doctor's interventions, Tavora-Vieira said.
"They should seek second opinion, particularly if the professional makes the diagnoses and offers no rehabilitation options," she said.
Source: Paediatrics, June 8, 2015.
Image: AUCKLAND - JUNE 09 2014:Newborn Infant (Naomi Ben-Ari age 0) during hearing screening.Significant hearing loss is the most common disorder at birth. Approximately 1%-2% of newborns are affected from Shutterstock