Definition

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

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 combination of these problems

Risk Factors

Factors that may increase your chance of AN include:

• Family history of hearing loss
• Lack of oxygen at birth
• Very low birth weight
• Jaundice after birth
• Gilbert’s syndrome —a genetic disorder
• Neurological disorders such as Charcot-Marie-Tooth Syndrome and Friedreich’s ataxia
• Infectious disease, such as mumps or meningitis
• Immune disorders
• Exposure to chemicals or medications that cause hearing loss, such as aminoglycosides, loop diuretics, and some chemotherapies
• Tumors of the nerve or those that compress the nerve
• Neurofibromatosis type 2 —genetic disorder of the nervous system and skin
• Trauma

Symptoms

AN may cause:

• White noise—the sound is heard, but the word is not clear
• Sounds to tune in and out
• Words and sounds to seem out of sync
• Ringing in the ears— tinnitus

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

Goals of treatment include:

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

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 such as 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

Prevention

In many cases, the exact cause of AN is unknown. However, these steps may help:

• If you are pregnant, ask your doctor how you can avoid infections
• Talk to your doctor if you have any conditions related to AN

National Institute on Deafness and Other Communication Disorders http://www.nidcd.nih.gov

Speech-Language and Audiology Canada http://www.caslpa.ca

Causes of hearing loss. My Baby’s Hearing website. Available at:
http://www.babyhearing.org/HearingAmplification/Causes/Neuropathy.asp
Accessed May 30, 2014.

Cochlear implants. American Academy of Otolaryngology website. Available at:
http://www.entnet.org/?q=node/1330
Updated January 2013. Accessed May 30, 2014.

Ototoxic medications (medication effects). American Speech-Language-Hearing Association website. Available at:
http://www.asha.org/public/hearing/Ototoxic-Medications
Accessed May 30, 2014.

Ototoxicity. Vestibular Disorders Association website. Available at:
http://vestibular.org/ototoxicity
Accessed May 30, 2014.