Although age (presbyacusis) is considered to be one of the primary causes for hearing loss this is not necessarily always the case. Hearing loss (temporary or permanent) can occur at any time and may be as a result of any of the following:
Acquired hearing loss:
Traumatic:
Physical trauma - blow to the head
Noise trauma - exposure to steady rate of noise
Acoustic trauma - exposure to repeated loud sounds such as gun fire
Blast injury - explosions
Barotrauma - pressure changes due to flying or diving
Miscellaneous - radiation exposure, electric shock
Iatrogenic:
Surgical e.g. poor ear syringing techniques, post surgery operations such as a stapedectomy
Pharmacological - certain drugs
Infective:
Viral - measles, mumps, herpes zoster (shingles)
Bacterial - upper respiratory infections e.g. colds & flu which can lead to middle ear infections
Fungus - Otomycosis (fungus in the outer ear)
Parasitic - meningitis
Neoplastic:
Cancer of the middle ear, leukaemia, vestibulocochlea schwannoma (acoustic neuroma)
Metabolic:
Hormonal - Myxodema (hypothyroidism), diabetes, acromegaly - can cause excessive growth in children or soft tissue growth in adults
Others - Dyslipidaemia (too much fat in the blood), hyperuricaemia (gout-excessive uric acid in blood), renal failure where kidneys cannot cleanse body of impurities, causing toxicity
Vascular:
Arteriosclerosis (hardening of the arteries), hyper-tension (high blood pressure), other circulatory disorders
Ototoxic substances not iatrogenically introduced such as carbon monoxide, tobacco and alcohol
Meniere's disorder
Congenital hearing loss:
Pre-natal:
Genetically (some 50-60% of all cases are hereditary) - Osteo genesis imperfecta (brittle bones), ushers syndrome, gargoylism (skull/facial deformities), Waardenburgs syndrome, Treacher Collins syndrome, Allports syndrome, Paget's disease (softening of the bones with age), hereditary presbyacusis. The most common form of hereditary hearing loss is otosclerosis (restriction of middle ear bone movement)
Pre-natal maternal rubella - Mother contracts German Measles during pregnancy
Cyto megalovirus (CMV) - Mother contracts this herpes like virus with flu type symptoms
Ototoxicity
Congenital syphilis
Peri-natal:
Premature birth
Anoxia - oxygen deficiency at birth e.g. umbilical chord twisted around baby's neck
Birth Trauma - damage by forceps during delivery
Rhesus incompatibilities - Rhesus factors in father's & mother's blood can cause jaundice
