Shape of inner ear helps predict hearing loss for children with rare hearing loss disorder
March 23, 2017
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Findings could provide predictor for degree of hearing loss in children with enlarged vestibular aqueduct
CLEVELAND, Ohio — It may be possible to predict the severity of hearing loss for children diagnosed with enlarged vestibular aqueduct, according to a new study published in JAMA-Otolaryngology-Head & Neck Surgery. This retrospective chart review, authored by physicians and researchers within the University Hospitals Rainbow Babies & Children’s Enlarged Vestibular Aqueduct (EVA) Research Project, is one of the first such studies to find a direct connection between the increasing width of the vestibular aqueduct and the degree of hearing loss a child experiences over time.
“There is still much to learn about the true causes and impacts of EVA,” says Mustafa Ascha, MS, first author of the study and a researcher within the UH Rainbow Department of Otolaryngology. “The hope is that these findings will help parents of young children with EVA, and their physicians, better understand what lies ahead for their child’s hearing and speech based on the severity of that child’s malformation.”
The study analyzed the medical records of 52 children diagnosed with EVA from the UH Rainbow Department of Otolaryngology, selecting records with both a computerized tomography (CT) scan for diagnosis and a median of five sets of audiogram test data to measure speech reception threshold, or the minimum intensity of decibels at which a patient can recognize half of spoken words, and the percent of words the patient recognized. The longitudinal models used in the study are common in social sciences such as economics or sociology, but applications in biomedical research are still gaining traction.
For each millimeter increase in vestibular aqueduct size greater than 1.5 millimeters, the research team found an increase of 17.5 dB in speech reception threshold and a decrease of 21 percent in word recognition scores. Additionally, for every year after the initial audiogram, the speech recognition threshold for patients with EVA increased by 1.5 dB and word recognition decreased by an additional 1.7 percent. They caution, though, that these results only represent averages for patient hearing loss progression—EVA symptoms are highly variable.
Enlarged vestibular aqueduct is the most common inner ear malformation associated with sensorineural hearing loss, which is caused by issues in the cochlea or the neural pathways that carry sound to the brain. The malformation does not necessarily cause hearing loss, but both EVA and hearing loss are caused by the same types of underlying defects. There is no treatment specifically for EVA, however children experiencing hearing loss who have EVA are candidates for hearing aids or cochlear implantation depending on the degree of hearing loss.
“Since EVA is considered an orphan disease, affecting fewer than 200,000 people per year, focused research on it has been limited,” adds senior author Todd D. Otteson, MD, MPH, Chief of Pediatric Otolaryngology at UH Rainbow. “This study may not change the treatment protocols already in place for children diagnosed with EVA in the short term, but it will enable physicians and families to appropriately plan a care trajectory that maximizes the child’s quality of life.”
The UH Rainbow Enlarged Vestibular Aqueduct Research Project is a donor-supported program that aims to change the current research landscape for EVA syndrome by charting a new pathway for clinical research discovery. The EVA Research Project is currently recruiting participants for a national EVA patient registry to collect patient experiences. The voluntary patient database will provide future researchers with the information necessary to better evaluate and make recommendations for children with EVA.
About University Hospitals Rainbow Babies & Children’s Hospital
Internationally renowned, UH Rainbow Babies & Children’s Hospital is a full-service children’s hospital and pediatric academic medical center with experts in 16 medical divisions and 11 surgical specialties who offer nationally ranked care not available at other institutions in the region, including a center dedicated to adolescent and young adult cancer treatment and Northeast Ohio’s only single-site provider of advanced maternal fetal medicine and neonatology services. As an affiliate of Case Western Reserve University School of Medicine and the only Level I Pediatric Trauma Center in the region, UH Rainbow Babies & Children’s Hospital offers access to novel therapies, advanced technologies and clinical discoveries long before they are available nationwide. Rainbow pediatric specialists – all of whom also serve on the faculty at the School of Medicine – are engaged in today’s most advanced clinical research and are widely regarded as the best in the nation – and in some specialties, the best in the world. Learn more at Rainbow.org.