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—Caused by the inability of the sound 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 Copyright © Nucleus Medical Media, Inc.

Causes

Sound waves travel from the outside and through structures in the outer, middle, and inner ear. The auditory nerve transmits the signal to the brain where it is translated into sound. Interruption of the sound wave can occur in the ear structures, the auditory nerve, or in the brain where sound waves are translated. This interruption can result in deafness.

Deafness can be present at birth (or soon after) or acquired anytime throughout life. In many cases, the cause of deafness may be unknown.

Risk Factors

Factors related to fetal development and birth that may increase the chance of deafness include:

• Certain infections in the mother during pregnancy, including rubella or sexually transmitted diseases
• Certain medications taken by the mother that affect the fetus during pregnancy
• Premature birth
• Low birth weight
• Insufficient oxygen to the fetus during birth or other birth trauma
• Newborn jaundice, which can cause damage to the auditory nerve
• Certain genetic disorders
• Structural defects in the ear

Factors that may increase the chance 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
• Occupations with noise exposure without proper hearing protection
• Infections, such as meningitis or mumps
• Head or ear trauma
• Previous 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 be gradual or sudden depending on the cause. Signs of deafness can occur at any age. Some symptoms include:

• Inability or extreme difficulty hearing
• Feeling of ear fullness, pressure, or blockage
• In some, tinnitus may be present

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

• 1-4 months—lack of response to sounds or voices
• 4-8 months:
  • Disinterest in musical toys
  • Lack of verbalization, such as babbling, cooing, and making sounds
• 8-12 months—lack of recognition of child’s own name
• 12-16 months—lack of speech

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

Diagnosis

You will be asked about your symptoms and medical history. A physical exam will be done. As part of the diagnosis, your doctor may try to determine the following:

• Location of the problem
• Degree of loss
• Cause—not always possible to identify the exact cause of hearing loss, but this information can help guide treatment

Your 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 your 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 an important part of coping with deafness. Some forms of deafness can be partially treated with surgery. You and your doctor will discuss the best treatment options for you.

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 your baby's life.

To help reduce the chance of deafness for you or your child:

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