What is Deafness?
There are two major types of deafness: sensorineural, which is caused by interference with the inner ear’s ability to process sound; and conductive, caused by anything that prevents sound-waves from reaching the inner ear (such as ear wax). Sound waves are vibrations created in the air. The vibrations pass through the outer and middle portions of the ear into the inner ear. There are tiny hair like cells that line the cochlea (the bony, snail-shaped structure where hearing is received), transform the vibrations into nerve impulses. These pass along the auditory nerve to the brain for interpretation. Rarely, there may be damage to the auditory nerve from a brain tumor or other serious neurological disorder.
Symptoms & signs of Deafness
- Decreasing ability to hear the radio or television at volumes that are comfortable to others.
- Difficulty in hearing in noisy situations, such as groups, family meals, etc.
- Social isolation, depression, and even confusional states in the elderly.
What causes Deafness?
Most sensorineural deafness is due to damage to the delicate hairs or nerve fibers in the cochlea. Gradual hearing loss due to cumulative damage occurs as a natural process beginning in childhood. However, a 30% loss in hair cells can be sustained without measurable hearing impairment. The other common causes of sensorineural hearing loss are:
- Natural ageing process: one to six people over the age of 70 years need a hearing aid.
- Viral labyrinthitis: an infection in the inner ear.
- Excessive noise: This can be chronic exposure to loud music or other sounds, or short-term exposure to very loud noise.
- Medications that damage the tiny inner ear structures: Aspirin (temporary), antibiotics, quinine and some diuretics (drugs that help remove excess water from the body) are the most common examples.
- Meniere’s disease: This causes dizziness and tinnitus (ringing in the ears) in addition to deafness.
These kind of deafness are characterized by the patients mild to moderate loss of discrimination of speech.
Conductive Deafness may be the result of:
- Impacted earwax.
- Middle and outer ear infections: This is characterized by discharge and sometimes pain and always requires specialist medical attention.
- Otosclerosis: Here bones in the middle ear become fixed. This is a progressive disorder, beginning in young adults, and can be corrected by surgery.
- Perforated eardrum.