Home > Hearing Issues > Audiology Alert

INTRODUCTION
Unless hearing impairment is detected in its early stages, it may negatively impact the psychological and physical well-being of children and adults.

Prompt detection of hearing loss, coupled with the appropriate intervention, is critical to speech, language, and cognitive development in hearing-impaired children. Untreated
hearing loss in older adults has been correlated with deterioration in physical, emotional, social, and cognitive functioning.

Early evaluation of pediatric and adult cases will ensure the best-possible outcome.

PEDIATRIC HEARING LOSS
Approximately one in 1,000 infants is born with significant sensorineural hearing impairment. When hearing loss is discovered in early infancy, steps can be taken to minimize the pervasive effect of sensory deprivation. The outcome for children whose hearing impairment is identified within the first year of life is far superior to that of children whose impairment is discovered after the first year. If undetected, a child's hearing loss may be misdiagnosed in later life as a learning disability.

DETECTION
Hearing loss may not be detected without routine age-appropriate screening. Parents often do not suspect a hearing loss until their child fails to form words at 12 to 18 months of age. An infant with partial hearing loss may still respond to some sounds, leading the parent to assume that hearing is normal. In addition, hearing-impaired infants may learn to respond to visual cues in their environment, thereby masking the condition.

Numerous factors increase a child's risk of hearing loss. These include, but are not limited to:

• Parental history of sensorineural hearing loss prior to age 7
  
• Blood relative with early sensorineural hearing loss
  
• Family history of Waardenburg's syndrome
  
• Maternal drug or alcohol abuse during pregnancy
  
• Anatomic malformations of the head and neck
  
• Congenital infections
  
• Birth weight less than 1,500 grams
  
• Infantile measles or mumps

In nearly 50% of cases of congenital or early sensorineural hearing loss, no risk factor can be identified. However, certain findings, on physical examination, should increase the index of suspicion for hearing impairment. These findings include heterochromia of the irises, malformation of the auricle, dimpling or skin tags around the auricle, cleft palate or lip, narrow ear canals, and microcephaly.

If family history or physical examination indicates the possibility of hearing impairment, the child should be referred for complete audiometric testing. Age-appropriate tests that may be recommended by a consulting audiologist include:

• Auditory brainstem response (ABR)
  
• Tympanometry
  
• Visual reinforcement audiometry
  
• Conditioned play audiometry
  
• Otoacoustic emission (OAE) testing (advances now permit differentiation of neural and sensory deafness)
  
• Acoustic reflex
  
• Impedance

In-office sedation should be available and is sometimes necessary to ensure the child's cooperation.

INTERVENTION
Once hearing loss is detected, intervention is possible regardless of the child's age. The earlier treatment begins, the greater the chance that the child will develop to maximum potential. In the cases of medically non-treatable loss, hearing aid amplification and a program of communication development can be implemented in infancy. Technology has reached the point that even infants with very severe losses can be aided by hearing instruments.

AGE- OR NOISE-RELATED
HEARING LOSS
Noise-induced hearing impairment is a common cause of sensorineural hearing loss between adolescence and age 50. Impairment also may be attributed to such uncommon causes as:

• Otosclerosis
  
• Ototoxic drug exposure
  
• Trauma
  
• Tumor in the eighth cranial nerve

The prevalence of hearing impairment increases after age 50. Research indicates that approximately 25% of patients between ages 51 and 65 have hearing thresholds greater than 30 dB in one ear (the normal range being 0-20 dB). Hearing loss can be identified in over 40% of persons 65 and older. This number jumps to 50% in those 85 years and older.

CHALLENGES
Older persons often do not realize the degree to which their hearing loss negatively impacts their lives. Research indicates that older patients judge their hearing impairments to be less severe than their spouses judge it to be. The time between onset of hearing loss and treatment in these patients is ten years, on average.

In fact, only a fraction of adult patients with serious hearing impairments receive treatment, although advances in hearing aid technology mean that many could be helped before further physical or psychological deterioration occurs.

DETECTION
Because of the pervasiveness and social consequences of hearing loss, routine hearing screenings are indicated. Recommended screening methods include written clinical history-taking and physical examination, clinical techniques, and patient questionnaires. The following questions can help to determine if the patient should be referred for an audiological examination:

• Do you have difficulty hearing when someone speaks in a whisper?
  
• Do you find it difficult to follow conversation in a crowded room?
  
• Do you feel people are mumbling or not speaking clearly?
  
• Do you have ringing in your ears?

Appropriate audiological tests include:

• Otoacoustic emissions
  
• Auditory brain response
  
• Impedance
  
• Hearing
  
• Pure-tone audiometry
  
• Speech

TREATMENT
Early intervention is indicated in all instances of hearing impairment in children and adults. With the latest technologies, sensorineural and conductive loss are often treatable. Hearing aids are now of therapeutic value in cases of auditory nerve damage.

The Annals of Internal Medicine noted a measured improvement in social, cognitive, emotional, and communication function from hearing aid use in a group of elderly veterans with previously documented hearing loss. Infants whose loss was detected and managed before their first birthdays exhibited better communication skills than their counterparts who had not received early treatment.

Research on neural plasticity found that the organization of the central auditory system may change between the onset of impairment and the time a hearing aid is fitted. This suggests that a hearing device should be fitted before the auditory system has reorganized itself in such a way that the chance to improve hearing may have passed.

Exciting new work in neural plasticity also suggests that the enhanced auditory stimulation provided by hearing devices may induce
"secondary" plasticity in the auditory system, which might contribute to acclimatization effects. Ear and Hearing also reported that late-onset auditory deprivation appeared to be reversible in some cases with the use of hearing aids.

In all cases, the best-possible course of treatment should be determined on a patient-by-patient basis after thorough evaluation.

CONCLUSION
New hearing technology means that hearing impairment is often treatable, especially if caught before further deterioration occurs. Unfortunately, hearing loss is not always detected immediately, and patients do not always seek treatment promptly. Research shows, and experts agree, that early management of hearing impairment provides the best-possible
outcome in terms of psychological, cognitive, and physical functioning for the patient.

[Return to top of page]