Auditory Neuropathy

Definition

Auditory neuropathy (AN) occurs when the nerve system of the inner ear fails to process sounds coming from the outer ear.

The Ear

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Causes

The outer ear sends vibrations to the inner ear during the hearing process. Hair cells in the inner ear break down the vibrations into electrical signals. These are sent to the brain. The brain filters them as sound. There is debate about the exact cause of AN. It may be due to:

• Damage to the hair cells in the inner ear
• Bad connections between the hair cells in the inner ear and the nerve to the brain
• Damaged nerve
• A mixture of these problems

Risk Factors

These factors increase your chance of developing AN:

• Family history of hearing loss
• Lack of oxygen at birth
• Very low birth weight
• Gilbert's syndrome (a genetic disorder) that requires a blood transfusion
• Neurological disorders (eg, Charcot-Marie-Tooth Syndrome, Friedreich’s ataxia)
• Infectious disease (eg, mumps)
• Immune disorders
• Exposure to chemicals or medicines (eg, aminoglycosides, loop diuretics) that cause hearing loss
• Tumor
• Neurofibromatosis type 2 (genetic disorder of the nervous system)
• Trauma

Tell your doctor if you or your child has any of these risk factors.

Symptoms

If you have any of these symptoms do not assume it is due to AN. These symptoms may be caused by other conditions.

• The sound is heard, but the word is not clear (white noise)
• Sounds tune in and out
• Words and sounds seem out of sync
• Tinnitus (ringing in the ears)

The level of hearing loss can vary from mild to severe. People with AN may have trouble picking out words. Many cases involve children.

Diagnosis

Your doctor will ask about your symptoms and medical history. A physical exam will be done. Tests may include:

• Auditory brainstem response (ABR) to measure brainwave activity
• Otoacoustic emissions (OAE) to record how the cells in the ear respond to clicking sounds

Treatment

Talk with your doctor about the best treatment plan for you. Treatment options include the following:

• Working with a team of specialists, including:
  • Otolaryngologist (ENT)—doctor specializing in disorders of the ear, nose, and throat
  • Audiologist—doctor specializing in hearing loss
  • Speech-language pathologist—healthcare professional who specializes in communication disorders
• Using technology, such as:
  • Cochlear implants —surgically implanted electronic devices that stimulate the auditory nerve to send information to the brain
  • Hearing aids
  • Listening devices (eg, frequency modulation [FM] systems)
• Having speech-language therapy, such as:
  • Sign language
  • Speech-reading (also known as lip-reading)
  • Exercises combining listening skills with technology

Goals of treatment include:

• Saving current hearing skills
• Restoring lost hearing
• Finding new ways of communicating

Prevention

The exact cause of AN is unknown. However, these steps may help:

• If you are pregnant, ask your doctor how you can avoid infections.
• Have your baby’s hearing checked at each doctor’s visit.
• Talk to your doctor if you have any conditions related to AN.