Hearing loss is the total or partial inability to hear sound in one or both ears.

See also: Hearing loss of aging   

Minor decreases in hearing are normal after age 20. Hearing problems usually come on gradually, and rarely end in complete deafness.

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

• Conductive hearing loss (CHL) occurs because of some mechanical problem in the external or middle ear. The three tiny bones of the ear (ossicles) may fail to conduct sound to the cochlea or the eardrum may fail to vibrate in response to sound. Fluid in the middle ear can cause CHL.
• Sensorineural hearing loss (SNHL) results from a dysfunction of the inner ear. It most often occurs when the tiny hair cells (called cilia) that transmit sound through the ear are injured. This type of hearing loss is sometimes called "nerve damage," although this is not accurate.

CHL is often reversible -- SNHL is not. People who have both forms of hearing loss are said to have mixed hearing loss.

Screening for hearing loss is now recommended for all newborns. In children, hearing problems may cause speech to develop slowly.

Ear infections are the most common cause of temporary hearing loss in children. Fluid may linger in the ear following an ear infection. Although this fluid can go unnoticed, it can cause significant hearing problems in children. Any fluid that stays longer than 8 - 12 weeks is cause for concern.

Preventing hearing loss is more effective than treating it after "the damage is done."

Genetic:

• Osteogenesis imperfecta
• Leopard syndrome (multiple lentigines)
• Otosclerosis
• Robinson type ectodermal dysplasia
• Cockayne syndrome
• Bjorn pili torti and deafness syndrome
• Multiple synostosis syndrome
• Hunter syndrome
• Taybi oto-palato-digital syndrome
• Hereditary nephritis
• Mohr syndrome
• Hurler syndrome
• Waardenburg syndrome
• Kartagener syndrome
• Fronto-metaphyseal dysplasia syndrome
• Morquio syndrome
• Trisomy 13
• Multiple lentigines syndrome
• Treacher Collins syndrome
• Stickler syndrome

Congenital:

• Rubella syndrome
• Congenital atresia of the external auditory canal
• Congenital cytomegalovirus
• Congenital perilymphatic fistula
• Fetal methyl mercury effects
• Fetal iodine deficiency effects

Infectious:

• Meningitis
• Mumps
• Measles
• Ear infection (otitis media)
• Scarlet fever

Traumatic:

• Traumatic perforation of the eardrum
• Skull fracture (temporal bone)
• Acoustic trauma such as from explosions, fireworks, gunfire, rock concerts, and earphones
• Barotrauma (differences in pressure)

Toxic:

• Aminoglycoside antibiotics
• Ethacrynic acid - oral
• Aspirin
• Chloroquine
• Quinidine

Age-related:

• Age-related hearing loss (presbycusis)

Occupational:

• Any occupation with exposure to loud noises on a continuous day-to-day basis can result in hearing loss due to nerve end damage. Increased attention to conditions in the work environment has markedly decreased the likelihood of work-related hearing loss. See occupational hearing loss.

Other:

• Meniere's disease
• Acoustic neuroma

Temporary hearing loss can be caused by:

• The build-up of wax in the ear canal
• Foreign body lodged in the ear canal
• Injury to the head
• Allergy
• Blocked Eustachian tubes
• Scarred or perforated eardrum
• Ear infections (chronic otitis externa, chronic otitis media, malignant otitis externa)
• Reaction to medication such as aminoglycosides, chloroquine, quinidine

Wax build-up can frequently be flushed out of the ear (gently) with ear syringes (available in drug stores) and warm water. Wax softeners (like Cerumenex) may be needed if the wax is hard and impacted.

Care should be taken when removing foreign bodies. Unless it is easy to get to, have your health care provider remove the object. Don't use sharp instruments to remove foreign bodies.

Call your health care provider if:

• Hearing problems are persistent and unexplained
• Hearing problems adversely affect lifestyle
• Hearing problems go along with other symptoms such as ear pain

The medical history will be obtained, and a physical examination performed.

Medical history questions documenting hearing loss in detail may include:

• Is the hearing loss in both ears or one ear?
• Is the hearing loss mild or severe?
• Is all of the hearing lost (inability to hear any sound)?
• Is there decreased hearing acuity (do words sound garbled)?
• Is there decreased ability to understand speech?
• Is there decreased ability to locate the source of a sound?
• How long has the hearing loss been present?
• Did it occur before age 30?
• What other symptoms are also present?
• Is there tinnitus (ringing or other sounds)?
• Is there ear pain?

The physical examination will include a detailed examination of the ears.

Diagnostic tests that may be performed include:

• Audiometry (an electronic hearing test )
• Auditory response test
• CT scan of the head (if a tumor or fracture is suspected)
• X-ray of the head
• Tympanometry
• Caloric test
• MRI of the ear (see MRI of the head)

A hearing aid or cochlear implant may be provided to improve hearing.

Rakel RE. Textbook of Family Practice. 6th ed. Philadelphia, PA: WB Saunders; 2005:443-444.