Cochlear Implants Benefit Developmentally Delayed Children

Jenni Laidman

August 01, 2012

August 1, 2012 — Developmentally delayed (DD) deaf children may benefit with respect to cognitive performance if they receive cochlear implants early in life, according to results from a study of 204 children who underwent implantation.

The research, published in the August issue of Otology and Neurotology, evaluated cognitive development, adaptive behavior, and familial stress in 60 children with developmental delays and 144 children without, assessing their test results both before and after cochlear implantation.

In this retrospective study, John S. Oghalai, MD, associate professor of otolaryngology at Stanford University and director of the Lucile Packard Children's Hospital Hearing Center, Palo Alto, California, and colleagues found that children with developmental delays were older at time of implant (25 months vs 16 months for children without developmental issues) and had slower intellectual development than children without delays postimplant. However, the researchers note, when the data were adjusted for delay in implantation, the differences in intellectual development disappeared.

"Although children with DD have a normal developmental rate of adaptive behavior after cochlear implantation, their developmental rate of intelligence is lower, and they have higher stress levels than children without DD. However, our data suggest that if children with DD could be implanted as early as children without DD, their intelligence and stress outcomes would be improved," the authors write.

Providing DD children with implants could improve performance across the board, Dr. Oghalai says in a Stanford University press release. "There is synergism between different sensory inputs," Dr. Oghalai notes in the release. "And some of these kids are missing more than just hearing; they're often having trouble with vision or touch as well. If you can fix one of the sensory problems, it might help to mitigate the effects of the other disabilities."

Still, the study provides no direct evidence that DD children with cochlear implants performed better than those who did not undergo the procedure. Such a conclusion awaits a more detailed trial.

"A randomized, prospective, controlled clinical trial would effectively answer this question of whether to perform cochlear implantation in children with DD," the authors write. "We have started such a trial and are actively enrolling patients at our 2 sites." The National Institutes of Health–funded trial is ongoing at both the Lucile Packard Children's Hospital Hearing Center and the Baylor College of Medicine, Houston, Texas.

DD children frequently have several medical issues that require immediate attention, so hearing loss issues may take a back seat, the authors suggest. Because studies have shown that the youngest children benefit most from implant, this delay could be critical, the authors add.

Another barrier to earlier cochlear implants has been the belief that DD children who may not develop language will not benefit from cochlear implants. However, the authors contend such children can and do benefit. "For a child with both hearing loss and DD, the DD is likely to be the ultimate limiting disability affecting his/her long- term outcomes," the authors write.

"The issue is to catch these children early when they're in the neonatal intensive care unit, identify their hearing loss and be aggressive in following and treating them," Dr. Oghalai said in the press release. He recommends early hearing tests, with infants receiving hearing aids by 6 to 8 weeks and cochlear implants by 1 year — the minimum age for implants allowed by the US Food and Drug Administration.

To determine whether a child in this study was DD, researchers developed a definition of DD for hearing-impaired children based on the Diagnostic and Statistical Manual of Mental Disorders, 4th Edition. The definition relied on the child's performance on the Visual Reception score in the Mullen Scales of Early Learning test, because it relies on "nonverbal problem solving." For similar reasons, they used the Vineland Adaptive Behavior Scales Daily Living Skills test to measure adaptive abilities. Children 2 standard deviations or more below mean in the Mullen Scales of Early Learning visual test, and 1 standard deviation or more below mean in the daily living test and a single other Vineland Adaptive Behavior Scales domain (social, communication, motor skills), are considered to be DD.

Developmental disability is the most common developmental disorder in the United States, and hearing loss is the fourth most common, the authors write. Some 2 to 3 children of 1000 are born with significant hearing loss.

This work was supported by the National Institutes of Health. The authors have disclosed no relevant financial relationships.

Otol Neurotol. 2012;33:947-956. Abstract

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