Deafness

Definition

Deafness is a severe or complete loss of hearing. Deafness can occur in one or both ears. It can happen slowly or suddenly. Early detection and management can lessen the impact on quality of life.

Types of deafness may include:

• Conductive—Sound is not able to reach the inner ear.
• Sensorineural—Caused by disorders of the inner ear, auditory nerve, or areas of the brain involved with hearing. This type of loss is usually permanent.

Anatomy of the Ear.

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Causes

Sound waves travel from the outside and through structures in the outer, middle, and inner ear. The auditory nerve send the signal to the brain where it is translated into sound. The sound wave can be blocked in the ear structures, the auditory nerve, or in the brain where sound waves are translated. This block can result in deafness.

Deafness can be present at birth (or soon after) or happen anytime throughout life. The cause of deafness may be unknown.

Risk Factors

Things related to fetal development and birth that may raise the risk of deafness include:

• The mother having an infection during pregnancy, such as rubella or sexually transmitted infections
• Some medicines the mother took during pregnancy
• Premature birth
• Low birth weight
• The fetus does not get oxygen during birth or there is other birth trauma
• Newborn jaundice, which can damage the auditory nerve
• Some genetic disorders
• Structural defects in the ear

Things that may raise the risk of acquired deafness may include:

• Ear disorders, such as:
  • Recurrent or poorly treated ear infections
  • Inner ear disorders, such as Meniere disease or labyrinthitis
  • Changes to the bone structure of the ear— otosclerosis
  • Tumors
• Family history
• Working at jobs with a lot of noise and not having proper hearing protection
• Infections such as meningitis or mumps
• Head or ear trauma
• Past brain or ear surgery
• Sudden pressure changes— barotrauma
• Sudden excessive noise that damages the ear, such as an explosion
• Cogan syndrome, a rare autoimmune disorder

Symptoms

Symptoms may appear slowly or suddenly depending on the cause. Signs of deafness can happen at any age. Some symptoms include:

• Inability or extreme difficulty hearing
• Feeling of ear fullness, pressure, or blockage
• Some people may have tinnitus, or ringing in the ears

Symptoms of deafness in infants and toddlers may be noted at these stages:

• 1 to 4 months—does not respond to sounds or voices
• 4 to 8 months:
  • Not interested in toys that make noise or music
  • Does not babble, coo, or make sounds
• 8 to 12 months—does not respond to their name
• 12 to16 months—does not say any words

All children, including newborns, should be screened for hearing loss.

Diagnosis

The doctor will ask about symptoms and health history. A physical exam will be done. As part of the diagnosis, the doctor may try to learn:

• Where the problem is
• How much hearing has been lost
• The cause—it is not always possible to find the exact cause of hearing loss, but this information can help guide treatment

The ears may be tested. This can be done with:

• Otoscopy—a lighted scope used to see inside the ear
• Tympanometry to test the pressure of eardrum and other middle ear structures
• A brainstem auditory evoked response test
• Tuning fork test to the vibration of auditory bones
• Hearing tests— audiogram

Images may be taken of the ears and surrounding structures. This can be done with:

• MRI scan
• CT scan

Treatment

Treatment for deafness depends on the cause. Some types are permanent and cannot be treated. Lifestyle changes are a key part of coping with deafness. Some forms of deafness can be partly treated with surgery.

Prevention

Deafness may not be preventable in all people. Hearing screening for newborns can help ensure that hearing loss in young babies is detected and treated at the earliest possible stage. This will lessen the impact on the baby's life.

To help reduce the chance of deafness:

• Make sure all vaccines are up to date.
• Get proper prenatal care, including screening for infectious diseases.
• Avoid certain drugs during pregnancy.
• Think about genetic testing if there is a family history of deafness.
• Get prompt treatment for infections, including those that affect the ear directly.