Saturday, February, 11, 2012

Hearing loss

Table of Contents

Definition

Hearing loss is being partly or totally unable to hear sound in one or both ears.

See also:

  • Hearing loss - infants
  • Hearing loss of aging
  • Sensorineural deafness

Alternative Names

Decreased hearing; Deafness; Loss of hearing; Conductive hearing loss


Considerations

It is common to lose a little bit of hearing after age 20.

Hearing problems often start slowly over time. They rarely lead to total deafness.

There are many causes of hearing loss. Hearing loss can be divided into two main categories:

  • Conductive hearing loss (CHL) occurs because of a mechanical problem in the outer or middle ear. The three tiny bones of the ear (ossicles) may not conduct sound properly. Or, the eardrum may not vibrate in response to sound. Fluid in the middle ear can cause this type of hearing loss.
  • Sensorineural hearing loss (SNHL) is due to a problem with the inner ear. It most often occurs when the tiny hair cells (nerve endings) that move sound through the ear are injured, diseased, do not work correctly, or have died.

CHL can often be reversed. SNHL cannot be reversed. People who have both forms of hearing loss are said to have mixed hearing loss.


Common Causes

Hearing loss may be caused by fluid that stays in the ear after an ear infection. Ear infections are common in children.

Other ear problems that can cause hearing loss:

  • Buildup of wax in the ear canal
  • Foreign object stuck in the ear canal
  • Hole in the eardrum
  • Scar on the eardrum from repeat infections

Hearing loss that is present at birth (congenital) may be due to:

  • Birth defects that cause changes in the ear structures
  • Genetic conditions (more than 400 are known)
  • Infections the mother passes to her baby in the womb (such as toxoplasmosis, rubella, or herpes)

Infections that can damage the brain or nerves of the ear:

  • Measles
  • Meningitis
  • Mumps
  • Scarlet fever

The ear can be injured by:

  • Pressure differences between the inside and outside of the eardrum , often from scuba diving
  • Skull fractures (can damage the structures or nerves of the ear)
  • Trauma from explosions, fireworks, gunfire, rock concerts, and earphones

Other causes are:

  • Age-related hearing loss (presbycusis)
  • Acoustic neuroma
  • Meniere's disease
  • Use of certain medicines
  • Working around loud noises every day (can damage the cells needed to hear)

Review Date: 05/31/2011
Reviewed By: Linda J. Vorvick, MD, Medical Director, MEDEX Northwest Division of Physician Assistant Studies, University of Washington School of Medicine; and Seth Schwartz, MD, MPH, Otolaryngologist, Virginia Mason Medical Center, Seattle, Washington. Also reviewed by David Zieve, MD, MHA, Medical Director, A.D.A.M., Inc.

A.D.A.M., Inc. is accredited by URAC, also known as the American Accreditation HealthCare Commission (www.urac.org)