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Highlights in 2018 Pediatric Audiology Research

Smith, Joanna, MS; Wolfe, Jace, PhD

doi: 10.1097/01.HJ.0000552755.20230.4a
Tot 10
Free

From left: Dr. Wolfe is an adjunct assistant professor at the University of Oklahoma Health Sciences Center and Salus University and the director of audiology at Oklahoma City's Hearts for Hearing, where Ms. Smith is a founder and the executive director.

Henry Ford, the industrialist who revolutionized factory production with his use of the assembly line, is largely credited with making automobiles available to the common man and transforming the economic landscape of the United States. As one might expect of such a remarkable innovator, Ford was fond of education and lifelong learning. “Anyone who stops learning is old, whether 20 or 80. Anyone who keeps learning stays young,” he once said.

In pediatric hearing health care, practitioners must stay young at heart and in mind to provide optimal services. Ford would suggest that we can remain young by striving to learn more about our craft. Moreover, lifelong learning is imperative in this field as hearing technology and pediatric hearing health care services evolve and advance at lightning speed. In the mid-1990s when we formed the program that would eventually become Hearts for Hearing, we did not have digital hearing aids, the Desired Sensational Level prescriptive method for fitting hearing aids was not routinely integrated into hearing aid analyzers and fitting software, cochlear implants were not in mainstream use among children, and frequency-specific auditory evoked responses were just making it to audiology clinics. Today, we can offer so much more. But the evolution of pediatric hearing health care also compels practitioners to continue learning to provide evidence-based and best-practice services. It may not always be easy to keep up with the latest research, so here are brief summaries of some notable studies from 2018 that have influenced the hearing health care services at our clinic. We extend a hearty debt of gratitude to the scientists and clinicians who conduct research to advance clinical practice.

10. Take a new look at the ASSR. The auditory steady state response (ASSR) has received considerable interest over the past two decades as a measure that can provide a good estimate of the hearing sensitivity of infants and young children. However, the tone burst auditory brainstem response (ABR) has largely been considered the gold standard measure for hearing threshold estimation in infants, and many studies have shown fairly large discrepancies between ASSR and ABR thresholds of infants. Yvonne Sininger and colleagues compared ABR and ASSR thresholds of 102 infants and young children who were referred for diagnostic assessment to rule out hearing loss (Ear Hear. 2018;39(6):1207). They used an ASSR approach that employed CE-Chirp stimuli and an advanced analysis technique that evaluated the amplitude and phase of the ASSR response at a modulation frequency.

They reported that the participants’ ASSR thresholds were significantly lower than their ABR thresholds. Obtaining the ASSR thresholds at 500, 1,000, 2,000, and 4,000 Hz in both ears took an average of 19.93 minutes, whereas it took an average of 32.15 minutes to complete the ABR test at the same frequencies for both ears. Additional work with ASSR is needed to determine the correction factors required to estimate air- and bone-conduction hearing thresholds for infants and young children with a wide range of degrees and configurations of hearing loss, but the work of Sininger and colleagues suggests that ASSR may become a future staple in the newborn hearing assessment battery.

9. EAS is not just for grown-ups. Park and colleagues at the University of North Carolina's Cochlear Implant Program examined the potential benefits of electric-acoustic stimulation (EAS) in children who have preservation of low-frequency acoustic hearing after cochlear implantation (doi: 10.1097/AUD.0000000000000658). Compared with the children's performance with electric stimulation alone, Park, et al., found significant improvements in speech recognition in quiet and in noise when the children used a cochlear implant sound processor with an acoustic receiver to provide low-frequency acoustic amplification and mid- to high-frequency electric stimulation. This study serves as a reminder to clinicians to evaluate children's unaided hearing sensitivity after cochlear implantation and provide EAS for children with preserved low-frequency hearing.

8. Be open-minded to open fits. Johnstone and colleagues described a study that serves to remind clinicians of the importance of open fittings for children with normal to mild low-frequency hearing loss with moderate to severe mid- to high-frequency hearing loss (J Am Acad Audiol. 2018;29(4):348). They measured the localization abilities of 18 children with hearing loss and 18 age-matched children with normal hearing, and found that children with hearing loss exhibited more localization errors than their normal-hearing counterparts. They also reported that younger children experienced more localization difficulties than older children. Importantly, they found that open-fitted hearing aids improved localization in children who had been using occluding earmolds for less than six years but not for those who had been using occluding earmolds for over six years. This finding suggests the possibility of a sensitive period of localization development during which access to acoustic information must occur without ear canal occlusion. Of note, Johnstone and colleagues also reported that 94 percent of the children with hearing loss had immediate improvement in hearing their own voice with an open-fitted hearing aid.

7. Big baby OAEs. Hunter and colleagues have a long history of providing valuable insights that guide our electrophysiologic assessment of auditory function in children. Most recently, Hunter, et al., published a study that described distortion product otoacoustic emissions (DPOAEs) in normal-hearing infants followed longitudinally from birth to 15 months of age (Ear Hear. 2018;39(5):863). They also measured wideband middle ear absorbance over the same period. They found that DPOAE amplitude was greatest when the infants were 1 month old and declined significantly from 1 to 5 months (particularly from 2,000 to 8,000 Hz). Minimal changes occurred when the infants were 6, 9, and 12 months old. They also reported that the decrease in DPOAE amplitude corresponded with a decrease in wideband middle ear absorbance that occurred over the same period. This study provides a valuable normative database that may be used in interpreting clinical results in children from birth to 15 months of age.

6. Fatigue in children with hearing loss. Gustafson and colleagues from Vanderbilt University completed P300 evoked response measures, subjective questionnaires, and assessment of response time and lapses in addition to examining signs of fatigue in 34 children with mild to moderately severe hearing loss prior to and during the completion of sustained, demanding listening tasks (JSLHR. 2018;61(4):1000). Compared with baseline measures, the children with hearing loss showed reduced attention, longer reaction times, reduced P300 amplitudes, and higher levels of reported fatigue after completion of the difficult listening tasks. These findings add to the growing body of evidence that children with hearing loss experience greater fatigue related to their hearing difficulties. Pediatric hearing health care professionals should be sensitive to this issue and strive to support children with solutions to reduce fatigue (e.g., remote microphone use, noise management technologies, proactive communication strategies, etc.).

5. The inner ear does more than hear. Practitioners often develop a single-minded focus on the evaluation and management of auditory function. We must not forget that the inner ear also plays a big role in children's balance function. Although vestibular assessment and management fall squarely within the scope of practice of pediatric audiology, many of us are not intimately familiar with the subject. A special issue of Seminars in Hearing sought to address our limited knowledge of vestibular impairment in the pediatric population (Semin Hear. 2018 Aug; 39(3):227). If you work with children with hearing loss, you are almost assuredly working with children who have impaired vestibular function.

4. T levels and telepractice. Telepractice is a hot topic in pediatric hearing health care. Transportation difficulties prevent many families from attending serial audiology and listening and spoken language therapy appointments during the first few years of a child's life. Teletherapy has long been seen as a potential solution to this dilemma, but many audiology tasks do not seem particularly amenable to teletherapy. For instance, some practitioners may consider it impossible to complete visual reinforcement audiometry (VRA) to measure the T levels (i.e., electrical threshold) of young children with cochlear implants. Fortunately, Hughes and colleagues dared to achieve the impossible (JSLHR. 2018;61(8):2115). They measured a child's cochlear implant T levels using VRA with the child in the clinic and via telehealth with the child off-site, and reported no difference in mean T levels and incidence of success on T level measurement between the in-person and remote conditions. Although some hurdles remain in the quest to provide remote care that is comparable to in-clinic care, Hughes, et al., have taken a big step toward making remote programming a reality for children with cochlear implants.

3. Mommy on the mic! Benitez-Barrerra and colleagues explored the impact of remote microphone use on the access of young children with hearing loss to caregiver talk in the home (JSLHR. 2018;61(2):399). They used language environment analysis (LENA) recorders to record caregiver talk from 10 families over two consecutive weekends, one in which the families used remote microphone systems and one in which they did not. The researchers determined the total amount of caregiver talk (i.e., words) that was accessible to the child with and without using the remote microphone system. They found that children had access to 5,280 more words per day with the remote microphone system (a median increase of 42% more words per day). They also found that caregivers tended to speak more often to their children from a distance when using the remote microphone. Also, the caregivers generally had a favorable opinion of using a remote microphone system.

2. Getting it right with the ABR. Successful completion of a valid ABR assessment in infants is one of the most challenging tasks in all of audiology. Obtaining low-electrode impedance values and achieving a good fit of insert earphones while keeping a newborn in a restful state are an art in and of themselves. The clinician is also faced with the task of completing a valid ABR assessment that provides a comprehensive estimate of auditory function within the short window of time that the infant naturally sleeps. Furthermore, although the ABR is often referred to as an objective measure of auditory function, interpreting ABR results requires the clinician's subjective analysis of ABR waveforms. To facilitate accurate interpretation, the clinician must have a sound evidence-based protocol. Norrix and Velenovsky's review of clinical guidelines and research provides an important outline of the most important factors that clinicians must consider when interpreting ABR waveforms (Am J Audiol. 2018;27(1):25).

1. LOCHI 5-year update. The International Journal of Audiology (IJA) published a special issue that focused on the Longitudinal Outcomes of Children with Hearing Impairment (LOCHI) study. We described the importance of the LOCHI study in a previous Tot 10 article in The Hearing Journal (http://bit.ly/2PBGUmB). The special issue provides updates and further evidence of the importance of early intervention and implantation (Int J Audiol. 2018 May;57(sup2):S105). The LOCHI study also provides evidence of the importance of high-quality intervention, the role of the family in the child's listening and spoken language outcomes, and the impact of additional disabilities on the outcomes of children with hearing loss. 2018 certainly marked a prolific period for research in pediatric hearing health care. Here's hoping for continued developments and advances in 2019!

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