Hearing loss is one of the most common childhood disorders and has far reaching effects on communication and socialization in children. Language acquisition, the most commonly sought and measured outcome, is tightly linked to age at diagnosis of the hearing loss and the speed with which rehabilitation is instituted. Treatment is often not affected by the underlying cause of the hearing loss and should be initiated at the time of initial identification. History-taking and physical examination in the setting of pediatric hearing loss are straightforward and should include an assessment of motor milestones, balance, and vestibular function.
Key points
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Hearing loss is one of the most common disorders of childhood and has far reaching impact on communication.
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A working knowledge of the physical features associated with syndromic causes of hearing loss is essential.
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Findings on history and physical examination may help tailor the use of diagnostic and ancillary testing yielding a cost-effective approach.
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Early rehabilitation is essential and should not be delayed while determining the underlying cause.
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Vestibular and balance function should be assessed in all children presenting with hearing loss.
| ANSD | Auditory Neuropathy Spectrum Disorder |
| BOR | Branchio-oto-renal syndrome |
| CI | Cochlear implantation |
| CMV | Cytomegalovirus |
| CT | Computed tomography |
| SNHL | Sensorineural hearing loss |
| USH1 | Usher syndrome type 1 |
| VEMP | Vestibular evoked myogenic potentials |
| WS | Waardenburg syndrome |
Introduction
Don’t tell me the sky is the limit when there are footprints on the moon
The limits of the evaluative, diagnostic, and treatment algorithms for pediatric hearing loss are ever changing. What has driven the expansion in these domains beyond previous limits has been the development and evolution of a variety of diagnostic, surgical, and rehabilitative technologies. The relationship between hearing loss and technology extends back to the industrial revolution when exposure to loud machinery hastened the acquisition of deafness in workers. The technologies of war, and specifically, societies’ attempt to accurately document and compensate for damage from hearing loss after the First World War led Fletcher and Munson (1933) to carefully document normal hearing thresholds for the first time. This ability to identify and measure hearing loss was, and remains, essential to its treatment. In the past, noise exposure, and the hearing loss that ensued, was primarily the concern of soldiers, laborers, hunters, and musicians, and safety measures have been put in place to reduce these exposures, minimizing their impact on hearing. However, in this modern day, the evolution of technology continues to put us at risk. In fact, when measured, both the level and the constant nature of noise within our environment are truly remarkable. Consider the daily commute for example, which brings with it the noise associated with traffic and construction. Our days are filled with noise, over which we have little control, as well as considerable noise we volitionally introduce ourselves to, most frequently in the name of entertainment. We do this knowingly as consenting adults, but also expose our infants and children, for example, by introducing white noise machines, which promise the elusive goal of improved sleep at the potential expense of our child’s hearing. Technology is obviously not responsible for all forms of hearing loss, particularly in children. In fact, the relationship between hearing loss and technology is deeply entwined in that it is also responsible for some of the most significant advances in the treatment of hearing loss, and it is this relationship that provides the perspective for this article.
The most significant introduction of technology in the therapeutic domain for hearing loss has been the advent of cochlear implantation (CI). Before the introduction of CI, the treatment options and therefore outcomes in severe to profound sensorineural hearing loss (SNHL) were limited. Although there were means available for measuring hearing loss, there was however less of an impetus to identify it early. However, the introduction of CI as an effective treatment option, where performance is ultimately tied to early identification and implantation within critical developmental periods, has driven the development and implementation of early identification strategies such as newborn hearing screening. Similar examples can be found in many domains surrounding pediatric hearing loss and are highlighted throughout this article. This article does not provide a laundry list of all possible features detected on history and all findings on physical examination in the child presenting with hearing loss. Rather, this article aims to arm the clinician with an approach to the child with hearing loss that focuses on the information that is relevant to today’s limits in the domains of diagnosis, treatment, and the prediction of outcome. It focuses on how this entwined relationship between hearing loss and technology has shaped the field, focusing on the newest additions to the clinical armamentarium, while also acknowledging that tomorrow there may well be footprints on Mars.
Introduction
Don’t tell me the sky is the limit when there are footprints on the moon
The limits of the evaluative, diagnostic, and treatment algorithms for pediatric hearing loss are ever changing. What has driven the expansion in these domains beyond previous limits has been the development and evolution of a variety of diagnostic, surgical, and rehabilitative technologies. The relationship between hearing loss and technology extends back to the industrial revolution when exposure to loud machinery hastened the acquisition of deafness in workers. The technologies of war, and specifically, societies’ attempt to accurately document and compensate for damage from hearing loss after the First World War led Fletcher and Munson (1933) to carefully document normal hearing thresholds for the first time. This ability to identify and measure hearing loss was, and remains, essential to its treatment. In the past, noise exposure, and the hearing loss that ensued, was primarily the concern of soldiers, laborers, hunters, and musicians, and safety measures have been put in place to reduce these exposures, minimizing their impact on hearing. However, in this modern day, the evolution of technology continues to put us at risk. In fact, when measured, both the level and the constant nature of noise within our environment are truly remarkable. Consider the daily commute for example, which brings with it the noise associated with traffic and construction. Our days are filled with noise, over which we have little control, as well as considerable noise we volitionally introduce ourselves to, most frequently in the name of entertainment. We do this knowingly as consenting adults, but also expose our infants and children, for example, by introducing white noise machines, which promise the elusive goal of improved sleep at the potential expense of our child’s hearing. Technology is obviously not responsible for all forms of hearing loss, particularly in children. In fact, the relationship between hearing loss and technology is deeply entwined in that it is also responsible for some of the most significant advances in the treatment of hearing loss, and it is this relationship that provides the perspective for this article.
The most significant introduction of technology in the therapeutic domain for hearing loss has been the advent of cochlear implantation (CI). Before the introduction of CI, the treatment options and therefore outcomes in severe to profound sensorineural hearing loss (SNHL) were limited. Although there were means available for measuring hearing loss, there was however less of an impetus to identify it early. However, the introduction of CI as an effective treatment option, where performance is ultimately tied to early identification and implantation within critical developmental periods, has driven the development and implementation of early identification strategies such as newborn hearing screening. Similar examples can be found in many domains surrounding pediatric hearing loss and are highlighted throughout this article. This article does not provide a laundry list of all possible features detected on history and all findings on physical examination in the child presenting with hearing loss. Rather, this article aims to arm the clinician with an approach to the child with hearing loss that focuses on the information that is relevant to today’s limits in the domains of diagnosis, treatment, and the prediction of outcome. It focuses on how this entwined relationship between hearing loss and technology has shaped the field, focusing on the newest additions to the clinical armamentarium, while also acknowledging that tomorrow there may well be footprints on Mars.
Prevalence and impact hearing loss
Hearing loss is one of the most common disorders of childhood. Approximately 14.9% of US children have low-frequency or high-frequency hearing loss of at least 16 dB hearing level in one or both ears. Profound, early-onset deafness is present in 4 to 11 per 10,000 children, with the overall estimates for congenital onset hearing loss ranging from 1 to 6 per 1000 newborns.
The challenges of managing hearing loss extend beyond simply hearing and affect many aspects of communication. Specifically, compared with children who have normal hearing, those with hearing loss will face additional challenges with many aspects of verbal communication and socialization (ie, vocabulary, grammar). There can be demonstrable deficits in language quotients in unrehabilitated hearing loss. These deficits can occur as early as 18 months of age when hearing loss is unrehabilitated. It is therefore important to identify and rehabilitate children with hearing loss as early as possible.
Symptom criteria
Hearing loss can be categorized in any number of ways. Typically, distinction is made between SNHL, which relates to deficits in the cochlea or the neural elements supplying or supplied by it, and conductive hearing loss, which relates to a deficit in the mechanical transmission of sound waves from the external auditory canal, through the eardrum and ossicles, to the cochlea. There are a large number of etiologic mechanisms contained within these 2 categories. Beyond this distinction, hearing loss can be characterized by its onset (ie, congenital vs acquired), its time course (ie, progressive vs nonprogressive), its severity (mild to profound), or its associated cause (ie, syndromic vs nonsyndromic; genetic vs nongenetic). For the purpose of this article, the clinical history and physical examination of the child with SNHL are the main focus.
Clinical findings
In most cases, hearing loss is nonsyndromic in nature, and most commonly, there are no outward signs of the disorder. Although some parents may recognize the failure to startle in children with profound SNHL, it can be exceedingly difficult to interpret the very subtle cues that suggest even very significant hearing loss in an infant or child. The reasons for this are that children remain very motivated to connecting with their environment and those around them. Even in the complete absence of hearing, they have a remarkable ability to use social cues associated with vision, and other sensory cues in their environment, to respond in ways that make it difficult for their caregivers to perceive the hearing loss; this can be compounded by caregiver denial that there is a sensory deficit with their child.
As a result, the most common indicator of hearing loss before infant hearing screening was failure to develop language. In the absence of screening, the age of detection for severe to profound SNHL ranged between 2 and 3 years of age. For less severe or unilateral hearing loss, this age was even older, often only being recognized when the child was able to articulate a difficulty with hearing or had failed a school screening. The challenges of reliably detecting hearing loss coupled with the need for early rehabilitation make hearing loss an ideal disorder to subject to a screening protocol. Jurisdictions in which neonatal screening for hearing loss has been instituted have seen a dramatic reduction in the age of detection, the age at which intervention has been instituted, and ultimately, the outcome. Screening, however, is not perfect, nor is it universal, even in developed countries. In addition, in some cases hearing loss may not occur until later in childhood and will therefore not be picked up by a screening protocol. In these instances, a normal hearing screen may provide undue reassurance to both clinicians and parents. Clinicians should not hesitate to re-refer into screening programs for further audiologic evaluation in children with normal screens where either new risk factors arose following the initial screen (ie, hyperbilirubinemia, meningitis) or with any delay in language or parental/clinician concern.
As mentioned above, most pediatric hearing loss is nonsyndromic in nature, and therefore, in many cases, there are no outward signs of the disorder. Not infrequently in such cases, the clinician may not detect a single abnormality on history or physical examination. In addition, unlike other conditions, even when abnormalities are noted on history and physical examination, this information has, in most cases, little relevance in determining a treatment course. As such, medical clearance for hearing aids should be initiated by the clinician who is first aware of the audiologic diagnosis, even if they do not consider themselves a hearing loss expert. One should not delay the initiation of hearing aids while waiting for a consultation with an expert in pediatric hearing loss or while undertaking the diagnostic evaluation. There is a fear of overamplification in children that is largely unfounded, and the authors suggest immediate and reasonable amplification as soon as it can be applied after diagnosis, regardless of cause.
So why, one might ask, do we continue to perform, teach, and advocate for a complete history and physical examination in children with SNHL? The true utility of the clinical history in this population is to guide the diagnostic protocol aimed at identifying the underlying cause of the hearing loss. In some centers, such as the authors’ center, the findings on clinical history and physical examination will be used to create an individualized, so-called “à la carte” approach to the use of further diagnostic modalities with the goal of containing cost. This approach is most relevant in a socialized, envelope-funded system but is increasingly becoming more relevant worldwide. Determining the cause, while again rarely essential to initial treatment, is advantageous for many reasons, not the least of which is providing families with the answer to the question: “Why does my child have a hearing loss?”. The psychological impact of answering this question should not be underestimated. In addition, determining the cause can indicate if the child is at risk for any other conditions and can also help predict the recurrence risk for hearing loss within the family. Although knowledge of outcome and performance based on cause is useful at the group level, it may be difficult to predict outcome based on cause at the individual level. Consistent with the underlying theme of this article, when it comes to the clinical history in children with hearing loss, questions are only asked based on access to diagnostic means. Finally, the clinical history also provides the opportunity to educate, which is of particular relevance in the setting of noise exposure and immunization.
As with any clinical complaint, in this case hearing loss, inquiry regarding the onset, variability, and associated signs and symptoms of the presenting complaint, is carried out.
Review of Risk Factors for Hearing Loss
Most importantly, the history should contain a review of known risk factors for hearing loss.
Perinatal history
Risk factors for SNHL can be elucidated by eliciting the prenatal and perinatal history. Specifically of relevance is a history of prematurity and the underlying inciting factor if known. In the setting of prematurity, a thorough history of the course and sequelae (ie, hypoxia, sepsis, hyperbilirubinemia) is relevant, particularly as they may support a cause for an audiologic diagnosis of auditory neuropathy spectrum disorder (ANSD). Exposure to antibiotics or diuretics throughout the course of prematurity may point toward an ototoxic exposure. The occurrence of any intrauterine infections and, in particular, a suspicion or confirmation of cytomegalovirus (CMV) even in the asymptomatic child is becoming increasingly relevant.
Family history
Beyond the perinatal history, a review of family history of hearing loss at a young age as well as a history of consanguinity may increase suspicion for an underlying genetic cause. It should be noted however that the most common genetic causes of hearing loss are recessive in nature; therefore, genetic hearing loss frequently presents in families where no other individual is affected. Families are often surprised by this notion that their child might be the index case, and it is an ideal opportunity to educate them on the importance of heightened awareness for the potential of hearing loss in other siblings and cousins within the family.
Delays of motor milestones
A history of delayed motor milestones ( Table 1 ) may increase the suspicion of an associated vestibular disorder, more common in children with cochleovestibular anomalies, some syndromic causes of hearing loss (ie, Usher and Pendred syndromes), acquired infectious causes of hearing loss (ie, meningitis and CMV), ototoxicity, or ANSD.
