Hearing Impairment Clinical Presentation

Updated: Jul 14, 2017
  • Author: Rahul K Shah, MD, FACS, FAAP; Chief Editor: Ravindhra G Elluru, MD, PhD  more...
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Presentation

History

General presentation and age at detection

Before neonatal hearing screening was routine, deafness was diagnosed at a mean age of 2.5 years. Since the implementation of successful Universal Newborn Hearing Screening (UNHS) programs, this improved to a mean of 14 months, with 74% being diagnosed and receiving intervention by 6 months. Harrison et al reported the average age of diagnosis to be just 2-3 months. [26]

The goal is universal screening, aimed at detecting hearing loss prior to 3 months and initiating appropriate intervention prior to 6 months, in accordance with the Newborn and Infant Hearing Loss: Detection and Intervention policy statement from the American Academy of Pediatrics (AAP). [2]

In a screened population, the rate of referral for services before 6 months is 19 times higher than in an unscreened population. The rates for confirmation and management of hearing loss are five times higher and eight times higher, respectively, for a screened population.

In the unscreened population or for those with progressive or acquired hearing loss, parents are the first to suspect hearing loss in almost two thirds of the patients. Pediatricians detect roughly 10% of cases, and other healthcare providers suspect it first in approximately 15% of patients. The mean time from the first suspicion of hearing loss to its diagnosis is 9 months.

High-risk criteria for hearing loss in neonates and infants

Before the implementation of UNHS programs in most states, the high-risk criteria were an important tool in the early detection of hearing loss. However, the dissemination of high-risk criteria for neonates and infants in 1990 did not notably alter the mean age at diagnosis. About 50% of children with sensorineural hearing loss (SNHL) do not meet any of the criteria listed, and only 10% of neonates have one or more of the high-risk criteria that prompt an evaluation.

These rates were among the reasons cited for the need for universal neonatal hearing screening. However, these criteria (especially for age 29 days to 2 years) serve as a reminder for those children for whom providers should have an increased level of suspicion and a decreased threshold to refer for testing for missed congenital, progressive, or acquired hearing loss.

High-risk criteria for neonates (birth to 28 days) are as follows:

  • Family history of congenital or early SNHL
  • Congenital infection known to be associated with SNHL
  • Craniofacial anomalies
  • Birth weight below 1500 g (<3.3 lb)
  • Hyperbilirubinemia over the exchange level
  • Exposure to ototoxic medications
  • Low Apgar scores at birth
  • Prolonged mechanical ventilation
  • Findings of a syndrome associated with SNHL

High-risk criteria for infants (29 days to 2 years) are as follows:

  • Concern about hearing, speech, language, or developmental delay
  • Bacterial meningitis
  • Neonatal risk factors associated with SNHL
  • Head trauma, especially with fracture of the temporal bone
  • Findings of a syndrome associated with SNHL
  • Exposure to ototoxic medications
  • Neurodegenerative disorders
  • Infectious diseases associated with SNHL

Indications for hearing evaluation and findings

Concern about a child's hearing loss expressed by a parent or caregiver always should prompt immediate evaluation. Hearing loss can be diagnosed at whatever age it is suspected, so delaying the diagnosis in the belief that a child is too young to be tested is unjustified. Other causes of language delay or behavioral problems should be considered as well, but hearing loss may be the cause of these problems. The results of referral for hearing loss are definitive, whereas evaluations for language or behavioral problems are more subjective and dependent on the skill of the person providing the evaluation.

Children with congenital or perinatally acquired profound SNHL (>90 dB) may present with loss of cooing by the age of 6-9 months and with frank language delay. Those with hearing loss less severe than this may present with minor speech impediments, language delay, behavioral problems, or school failure. The degree of hearing loss or loss of speech discrimination correlates with the patient's speech and language problems.

Behavioral problems may be major or minor, and they are probably best correlated with the child's personality and with how the parents deal with what they may consider a stubborn child. Before speech impediments, mental retardation, autism, attention deficit, or adjustment disorders are presumed, many children could benefit from a hearing evaluation.

Upon evaluation, a child who cannot hear normal speech can reproduce only what he or she hears. A child who cannot hear the teacher cannot learn. In addition, a child who is bored fidgets. A child who cannot understand and who is berated by caregivers for lack of cooperation may act out.

Healthcare providers should understand that normal speech volumes are 30-50 dB, whereas typical street traffic is about 60 dB. Standard phones ring and shouts register at approximately 80 dB, and lawnmowers are approximately 90 dB. Therefore, children with a 60-dB hearing loss hear their mother when she yells at them and startle when the telephone rings. However, they do not hear most conversational speech, and they may not always hear the teacher in a classroom, especially if they are not in the front and there is significant extraneous noise.

If children have poor speech discrimination, the diagnosis is usually made relatively early because they may mispronounce words or may be unable to understand what is being said. In children with good speech discrimination, hearing loss may go undetected because speech production and comprehension are less affected.

Children with mild hearing losses that begin prelingually or postlingually may present with difficulties late in childhood.

In general, children who lose their hearing postlingually present with a decline in language skills they had previously achieved. In children of this age group, clinically significant hearing loss is usually the result of an obvious medical event. Those who lose their hearing postlingually may be able to describe their loss. However, if the decline is gradual, they may not initially recognize the deficit.

Worsening speech or school performance may herald long-standing or progressive mild-to-moderate hearing loss. Other presentations of mild or progressive hearing loss may be withdrawal from social activities and playing alone, or playing the television and music with increasingly loud volumes.

Next:

Physical Examination

Children with congenital hearing loss should be carefully evaluated for any evidence of other physical stigmata or for possible associated syndromes (ie, a white forelock to suggest Waardenburg syndrome). (For a partial list of syndromes related to deafness, see Etiology.) Because almost every organ system can potentially provide evidence of an associated syndrome, detailed physical examination is necessary.

For patients with acquired hearing loss, an otolaryngologist should evaluate the ears by inspecting them for external defects or for obstructions that block sound conduction down the ear canal (eg, cerumen, foreign bodies). In addition, pneumatic otoscopy should be performed to detect any evidence of current or chronic infections, such as perforation or scarring of the tympanic membrane, cholesteatoma, abnormal landmarks, and fluid behind the tympanic membrane.

The remainder of the otolaryngology examination should be focused on the head and neck to carefully rule out other abnormalities that may lead to a diagnosis.

If children are old enough to cooperate, they should undergo tests of balance because dysfunction of the inner ear or vestibular nerve may also be present.

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