Throughout the 1970s and into the early 1980s, hearing health care professionals often underestimated the potentially deleterious effects of unilateral hearing loss (UHL; Northern & Downs. Wilkins, 1978 http://bit.ly/2DTRZVL). The prevailing modus operandi suggested that one normal-hearing ear was more than sufficient to support the typical development of speech, language, social, and academic abilities. This misguided line of thinking was turned upside-down in 1986 when the research of Fred Bess, PhD, Anne Marie Tharpe, PhD, and colleagues showed that children with UHL were 10 times for likely to fail a grade in school than their peers with normal hearing. Almost 20 years later (in 2005), the U.S. Centers for Disease Control and Prevention hosted a workshop that acknowledged the difficulties encountered by children with UHL. It also recognized the fact that there was no professional consensus on the ideal way to identify children who may be at risk for developmental delays because of UHL. Additionally, experts at the workshop noted the limited evidence supporting the potential of any type of intervention that may alleviate the deficits associated with UHL. Since then, the hearing health care community did not reconvene to advance the standard of care for children with UHL until recently. In October 2017, Tharpe chaired the Unilateral Hearing Loss in Children Conference 2017 http://bit.ly/2DS33Tc, which featured current research presented by many of the foremost experts on UHL. Here are some conference highlights.
10. Learning from Lieu
Judith Lieu, MD, has conducted several studies examining the consequences of UHL on children's communicative, academic, and social development. At the conference, Lieu reported that the consequences of UHL reach far beyond difficulty with localization and speech recognition in noise. Children with UHL are inclined to have language delays that first manifest in early childhood and persist through adolescence. She described research findings that showed how children with UHL used language that lagged behind that of their siblings with normal hearing. She also shared that her research confirmed the findings of Bess and Tharpe that children with UHL are 10 times more likely to fail a grade in school than their normal-hearing peers, and are also far more likely to need additional academic resources (e.g., Individualized Educational Plan). Moreover, she noted that children with UHL are more likely to have behavioral issues than children with normal hearing. Factors such as family poverty, parental education, non-verbal IQ, and degree of hearing loss influence the outcomes of children with UHL. Finally, she reviewed recent research exploring brain imaging to examine the differences between the physiologic responses of children with UHL and children with normal hearing. Imaging studies have shown that some children with UHL have functional changes in the complex neural networks that govern everyday tasks such as listening, reading, etc. For instance, some children with UHL demonstrated reorganization of certain areas of the brain so that auditory weaknesses could be supported by other regions and networks involved in processes like vision, language, motor, etc.
9. UHL in the Real World
Dawna Lewis, PhD, has developed an impressive laboratory that allows for the simulation of environments children commonly encounter in the real world (e.g., classroom). Recently, she studied the impact of UHL on children's speech recognition and communication strategies in complex settings. Lewis reported that children with UHL struggle to understand speech in an environment with multiple speakers and when the speaker of interest changes throughout the situation. Lewis also noted that the availability of visual information (i.e., visualizing a speaker's mouth moving) improves the ability of many children with UHL to locate a speaker. However, she also reported that many children with UHL often take longer than their peers with normal hearing to locate a speaker in a small group. She postulated that the effort needed to locate the speaker of interest may require cognitive resources that could negatively affect speech comprehension.
8. UHL can be a Real Drag
Benjamin Hornsby, PhD, shared the results of research examining fatigue in people with hearing loss. Fatigue is not simply brought on by high effort. Instead, it is a complex “state of mind” that is influenced by the resources required to maintain “acceptable” performance. Hornsby noted that fatigue occurs more likely if poor performance is met with negative consequences and if the listener feels that his/her effort toward a goal is not worth the reward. People with bilateral hearing loss have shown to exhibit higher levels of fatigue than those with normal hearing. Hornsby noted that research on measuring fatigue in children with UHL is limited, but that preliminary research suggests fatigue to be more likely a problem for children with UHL, especially if they have poor language abilities and self-perceived hearing difficulties.
7. Can we Predict Outcomes of Children with UHL?
Christine Yoshinaga-Itano, PhD, discussed the factors that influenced the outcomes of 132 children with UHL and reported that language outcomes measured at 3 years of age were not influenced by gender, affected ear (right or left), degree of hearing loss, home language, parents’ hearing status, use of amplification, or Medicaid status. In contrast, the mother's level of education was positively correlated with the language outcomes of children with UHL. Yoshinaga-Itano noted that language delays were not generally observed during the first year-and-a-half of a child's life but did emerge in many children with UHL by 2 to 3 years of age. Accordingly, she recommended that all children with UHL be evaluated for delays at 24 months of age and that intervention be provided as needed. She did note that about half of the children with UHL in her study showed delays in vocabulary and comprehension of abstract language at 24 months of age even when enrolled in the state's early intervention program.
6. Checking with CHEO
Elizabeth FitzPatrick, PhD, of the Children's Hospital of Eastern Ontario (CHEO), shared a review of audiology services at CHEO for 108 children with UHL from 2003 to 2015. Of note, she reported that the average age of identification of children with UHL was 5.4 years old prior to newborn hearing screening and about 4 months of age after the advent of universal newborn hearing screening. Early identification of UHL presents clinicians with the opportunity to provide early intervention and possibly stem the tide of deficits that may occur. However, early identification of children with UHL also forces clinicians to make intervention decisions for a population for which there is very little evidence of the efficacy of available intervention options. Accordingly, Fitzpatrick noted that a large delay existed between the identification of UHL (most prior to 1 year of age) and the age at which amplification was fitted (mean=42.9 months). Fitzpatrick also reported on a tangential study exploring the outcomes of 38 children with UHL. Less than 40 percent of these children consistently used amplification immediately after the loss was identified, whereas by 4 years of age, only 46 percent consistently used amplification. Furthermore, she reported that children with UHL were more likely than their normal-hearing peers to have deficits in language development and difficulties with speech recognition in noise. Unfortunately, amplification use did not influence auditory and language outcomes, although some families did state that they perceived hearing aid use to be beneficial in real-world situations. Fitzpatrick stressed the need for more long-term studies exploring the outcomes of children with UHL and the factors that influence these outcomes.
5. So what do we do now?
Marlene Bagatto, AuD, PhD, summarized the complexities associated with determining whether amplification should be recommended for children with UHL. She referred to an addendum on amplification for children with UHL that was recently included in the Ontario Infant Hearing Program's Provision of Amplification Protocol (Version 2014.01 http://bit.ly/2EtMZr1). Pediatric hearing health professionals should check out this valuable resource that provides good counsel on making intervention decisions for young children with UHL.
4. Good Vibrations
Hillary Snapp, PhD, reviewed the potential advantages and limitations of bone conduction devices for people with UHL. She commented on the fact that the head shadow may prevent adequate access to the high-frequency components of speech when sound arrives from the side of the poorer ear. She noted that the use of a bone conduction device on the poorer ear may improve speech recognition of soft speech arriving from the side of the poor ear and may also improve speech recognition in noise when the speech arrives from the side of the poor ear. She also mentioned the recent development of objective real-ear verification measurements of bone conduction devices, a tool that should be routinely included in every pediatric audiologist's tool box (Hodgetts & Scollie, 2017). Finally, Snapp discussed the need for pediatric audiologists to provide patients and their families with thorough information on the advantages and limitations of various hearing technology options available.
3. What about a CI?
Doug Sladen, PhD, discussed the pros and cons of cochlear implantation for children with UHL. Cochlear implantation is the only technology that can partially restore auditory function in the poorer ear of a child with profound UHL. Sladen shared the results of his ongoing study that is exploring the outcomes of 33 adults and nine children with UHL who received a cochlear implant (CI). He reported that eight of the nine children use their CIs full-time. For both children and adults, cochlear implantation improved word recognition in the implanted ear and generally improved speech recognition in noise compared with the better-ear-alone condition. Sladen also noted that cochlear implantation may improve the quality of life of people with UHL. Of note, the benefits of CIs for children with congenital UHL are likely to be better if implantation is done during the first year or two of life. For children with later onset of severe to profound UHL, CIs should be promptly considered to avoid the negative effects of auditory deprivation. But since many children with congenital profound UHL have a deficient cochlear nerve, an MRI must be completed to evaluate the status of the cochlear nerve prior to cochlear implantation (Otolaryngol Head Neck Surg. 2013;149:318 http://bit.ly/2EudTiE).
2. This CROS will make you jump, jump!
Erin Picou, PhD, discussed her research on the benefits of Contralateral Routing of Signal (CROS) devices for children with UHL. Prior to her research, most studies that evaluated CROS devices for children with UHL were conducted almost 30 years ago. Picou commented on the evolution of the classroom over the years. Specifically, children may not always be seated in rows while listening to the teacher. Instead, seats in today's classrooms may be arranged in various configurations, and students often work in small clusters rather than listen to the teacher throughout the day. Picou's research examined the speech recognition and story comprehension of school-age children in a simulated classroom in which the signal of interest arrived from multiple locations. She reported that both remote microphone systems and CROS devices improved the children's performance in some situations. Particularly, the use of a CROS improved performance when the signal was sent toward the children's poorer ear. Across all listening conditions and tasks, the use of a CROS device enabled a small but consistent improvement in performance. She suggested the use of remote microphone systems in situations involving one primary speaker and for younger children who may be less likely to orient toward the speaker. She also suggested using CROS devices in classrooms in which peer input is important and for older students who reject the use of a remote microphone system.
1. Supporting the Whole Child
Cheryl Deconde Johnson, EdD, gave poignant reminders on the socio-emotional aspects of UHL. She shared a detailed case study that demonstrated how children with UHL have the risk of developing difficulties in peer-to-peer interaction and may be more inclined to have behavior issues in school. She also noted that some children with UHL may struggle with low self-esteem. There are several accessible tools and resources for pediatric hearing health care professionals to help support a child's hearing needs, academic needs, and overall well-being. An example is the position statement from the Educational Audiology Association http://bit.ly/2EspnmA on useful intervention strategies for children with UHL.
While no foolproof method exists to predict which children with UHL will experience difficulties in language, academic, and social development, the Unilateral Hearing Loss in Children Conference 2017 http://bit.ly/2DS33Tc provided much-needed updates on the assessment and management of these patients.
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