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Auditory Neuropathy

WHAT IS AUDITORY NEUROPATHY?

Auditory neuropathy is a hearing disorder where sound enters the inner ear normally but the transmission of signals from the inner ear to the brain is impaired. Auditory neuropathy affects patients ranging in age from infancy through adulthood, and can be congenital or acquired. It is unknown how many individuals have auditory neuropathy, but it is a relatively small percentage of the total number of people with hearing impairments. Individuals with auditory neuropathy may have normal hearing, fluctuating hearing, or a hearing loss ranging from mild to profound, but regardless of the level of the hearing impairment, auditory neuropathy is always associated with impaired ability to understand speech.

WHAT CAUSES AUDITORY NEUROPATHY?

There are likely multiple causes of auditory neuropathy. In some instances it may involve damage to the inner hair cells which transmit sound information through the nervous system to the brain. Other causes may include neurological damage of the auditory nerve (VIIIth cranial nerve). Hearing impairment associated with extremely premature birth (26 weeks gestation or earlier) and CytomegaloVirus (CMV) have a higher than average association with auditory neuropathy. Sometimes individuals with auditory neuropathy are subsequently diagnosed with an overall neurological disorder such as Charcot-Marie-Tooth disease, Friedreich’s ataxia, or Hereditary Sensory and Autonomic Neuropathies (HSAN).

WHAT ARE THE RISK FACTORS FOR AUDITORY NEUROPATHY?

Several factors have been linked to auditory neuropathy in children, including neonatal health problems, such as:

  • Jaundice;
  • Premature birth;
  • Low birth weight;
  • Inadequate supply of oxygen prior to birth; (twin to twin transfer syndrome, umbilical cord issues including missing vessels or entanglement/knotting)
  • Ototoxic drugs;
  • Genetic / Hereditary factors.

HOW IS AUDITORY NEUROPATHY DIAGNOSED?

 

Otolaryngologists and audiologists use a combination of testing methods to diagnose auditory neuropathy, primarily Otoacoustic Emissions (OAE) and Auditory Brainstem Response (ABR) testing. A diagnosis of auditory neuropathy is likely when there is abnormal ABR results combined with a normal OAE reading. A normal OAE reading is a sign that the outer hair cells are working normally, indicating that the problem with hearing is somewhere past the hair cells in the hearing pathway.

 

 

WHAT TREATMENT IS AVAILABLE TO HELP PEOPLE WITH AUDITORY NEUROPATHY COMMUNICATE?

Auditory neuropathy symptoms are very individual, and thus need to be managed on a case by case basis. Some individuals with auditory neuropathy have had success with Cochlear Implants (CI). Individuals with Auditory Neuropathy who are audiologically cochlear implant candidates frequently receive bilateral cochlear implants, because the “white noise” sound generated by the malfunctioning auditory nerve in an unimplanted ear can interfere with the ability to understand speech on the implanted side. Implanting both ears either sequentially or simultaneously eliminates this problem.

Hearing aids do not always benefit individuals with auditory neuropathy, however, FM systems have been found to be helpful for some patients.

CONCLUSION:

Auditory neuropathy is difficult to diagnose without a comprehensive medical examination and specialty care from an Otologist, who is an otolaryngologist (ENT) who has undergone two additional years of training and specializes in hearing only. With appropriate medical treatment and therapy, individuals with auditory neuropathy can fully function in a hearing world.

Click here to make an appointment with the California Ear Institute to consult with one of our board certified Otologists regarding your ear-related condition.


 
California Ear Institute