Ear Infections
Hearing loss due to ear infections (otitis media) commonly arises as the possible cause of hearing loss in children. Otitis media is an inflammation of the middle ear which gradually leads to a buildup of fluid, which may or may not be infected. The secretion of fluid may be caused by possible allergy, or a cold. In repeated or extreme cases, the fluid in the middle ear space may be infected and become thick and gluey, which may lead to a permanent hearing loss if the condition is not treated medically.
Hereditary traits
Genetic traits are thought to cause more than half of all incidents of hearing loss in children. If either one of a child's parents carries a gene for hearing loss, there is a 25% to 50% chance that the child may have some level of hearing loss. This probability increases if both parents have hearing loss or if both grandparents on one side of the family have hearing loss due to genetic causes. Some genetic syndromes related to abnormal hearing include:
- Down's Syndrome,
- Usher's Syndrome,
- Treacher Collins Syndrome
- Crouzon's Syndrome
- Alport's Syndrome.
Congenital Prenatal Causes
Other causes of hearing loss more common in children that are not hereditary include prenatal infections, illnesses or conditions that occur at or after the time of birth. These include:
- Infections caused by Rubella (German measles), Cytomegalovirus and Herpes Simplex Virus
- Complications due to the Rh factor in the blood (Hyperbilirubinaemia)
- Prematurity (With birth weight less than 1.5kg)
- Maternal diabetes
- Toxemia during pregnancy
- Anoxia - lack of oxygen.
Environmental Exposure to loud sounds
Prolonged exposure to loud noises can cause the gradual deterioration of the hair cells in the cochlear. This is normally a gradual process. Acoustic trauma, or sudden exposure to loud sounds, (usually over 85dB, in the instance of a sudden gun-shot sound...etc) can cause damage to the outer hair cells in the cochlea in less than 10 minutes.
Acquired diseases
Hearing loss due to this may occur at any time of a person's life. Common causes besides those already mentioned above, include:
- Meniere's Disease (characterised by deafness, vertigo and tinnitus in the ear)
- Meningitis
- Measles
- Mumps
- Head injury
- Hearing loss due to tumour (Acoustic Neuroma)
Certain medications
Certain prescriptions used for treatments can cause damage to the auditory system (Ototoxic drugs). These include:
- Aminoglycoside antibiotics, e.g. Streptomycin, Neomycin, Kanamycin...etc
- Large amounts of salicylates, e.g. Asprin for a long duration..etc
- Loop diuretics, e.g. Lasix, Ethacrynic Acid...etc
- Chemotherapy drugs, e.g. Cisplatin, Carboplatin, Nitrogen Mustard...etc
Physical disorders in the middle ear
Otosclerosis is a condition that leads to progressive hearing loss. It is caused by the gradual build-up of tiny bony tissue (calcium deposits) around the stapes (or stirrup) in the middle ear, thus affecting its movement. Other examples of physical disorders include:
- Fracture of the temporal bone involving the ear structures.
- Puncture of the eardrum by foreign objects.