Auditory Neuropathy

Auditory neuropathy (AN) occurs when the nerve system of the inner ear fails to process sounds coming from the outer ear. AN can affect any age group, from babies to adults.

During the hearing process, the outer ear sends vibrations to the inner ear. Hair cells in the inner ear break down the vibrations into electrical signals. These are sent to the brain, which filters them as sound. While there is debate about the exact cause of AN, it may be due to:

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

These factors increase your chance of developing AN:

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

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

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

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

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

Your doctor will ask about your symptoms and medical history. He will also do a physical exam. Tests may include:

• Auditory brainstem response (ABR)— electrodes are used to measure brainwave activity, helpful in assessing function of auditory nerve
• Otoacoustic emissions (OAE)—a tiny microphone is placed in the ear canal to record how the cells respond to clicking sounds; helpful in checking if hair cells are working normally

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

• Having speech-language therapy, such as:
  • Exercises combining listening skills with technology
  • Sign language
  • Speech-reading (also known as lip-reading)
• 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)
• Working with a team of specialists, including:
  • Audiologist—doctor specializing in hearing loss
  • Otolaryngologist—doctor specializing in disorders of the ear, nose, and throat
  • Speech-language pathologist—healthcare professional who specializes in communication disorders

Goals of treatment commonly include:

• Finding new ways of communicating
• Preserving existing hearing skills
• Restoring lost hearing

Since the exact cause is unknown, there are no clear ways to prevent this condition. These steps may help:

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