Definition

Hearing loss is a decreased ability to hear. There are two main categories of hearing loss:

Conductive hearing loss due to something interfering with the sound passing to the inner ear

Sensorineural hearing loss due to damage to:

• The major organ in the ear responsible for hearing (the cochlea)
• The major nerve pathway (8th cranial nerve) and/or area of the brain responsible for hearing

The Anatomy of the Ear

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Causes

Causes of conductive hearing loss include:

• Impacted ear wax
• Fluid in the middle ear
• Ear infections
• Perforation of ear drum
• Stiff bones in the middle ear ( otosclerosis )
• Injury
• Loose or fractured bones in the middle ear
• Missing bones from the middle ear due to previous surgery
• Congenital anomaly causing complete closure of the ear canal (Atresia)
• Tumors

Causes of sensorineural hearing loss include:

• Excess noise
• Aging
• Family history
• Exposure to toxic substances, including such drugs as:
  • Streptomycin
  • Gentamicin
  • Chemotherapy drugs
  • Diuretics
  • Steroids
  • Heart medicines
  • Anesthetics
  • Quinine
  • Aspirin-containing drugs
• Acoustic neuroma
• Cardiovascular disease
• Multiple sclerosis
• Viruses ( measles , mumps , adenovirus , rubella )
• History of meningitis or syphilis
• Neurologic diseases such as multiple sclerosis and stroke
• Inner ear disorders such as Meniere’s disease
• Otosclerosis affecting the inner ear
• Previous brain or ear surgery causing damage to the inner ear
• Trauma

Risk Factors

A risk factor is something that increases your chance of getting a disease or condition.

Risk factors for hearing loss include:

• Family history
• Aging
• Meniere's disease
• Not receiving all recommended immunizations
• Repeated or poorly treated ear infections
• Exposure to loud noise, music, or machinery
• Use of certain antibiotics and chemotherapy drugs
• Diseases that may result in blocked blood flow, including atherosclerosis , problems with blood clots, and collagen vascular diseases

Symptoms

Symptoms may include:

• Decreased ability to hear any of the following:
  • Higher pitched sounds
  • Lower pitched sounds
  • All sounds
  • Speech when there is background noise
• Dizziness
• Ringing sounds in the ears
• Problems with balance
• In children, hearing loss may cause difficulty learning to speak.

Diagnosis

The doctor will ask about your symptoms and medical history, and perform a physical exam. Tests may include:

• Weber test—a tuning fork sounded and placed on your forehead or teeth. This can help distinguish conductive from sensorineural hearing loss.
• Rinne test—a tuning fork sounded and placed in front and then behind of the ear. This can help distinguish conductive from sensorineural hearing loss.
• Audiometric tests —These involve listening to tones in a soundproof room and reporting whether or not you hear the tones.
• Tympanometry—This test measures the pressure in the middle ear and examines the middle ear's response to pressure waves.
• CT or MRI scan of the head —a type of imaging study that uses a computer to make pictures of the inside of the head. This may be done to check for a tumor or bone injury.
• Brain stem auditory evoked responses—electrodes attached to the scalp and used to measure the electrical response of the brain to sound
• Electrocochleography—This tests the cochlea and the auditory nerve.

Treatment

Treatment includes:

Prevention

To help prevent hearing loss:

• Stop smoking.
• Adequately treat ear infections.
• Get all appropriate immunizations.
• Treat all medical conditions.
• Avoid exposure to excess noise.
• Use adequate ear protection when using noisy equipment.