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Causes of Deafness

I. Genetic Causes

These are inherited or caused by genetic mutations, either present at birth or progressive over time.

  1. Syndromic genetic disorders (hearing loss with other symptoms):
    • Usher syndrome (deafness + vision loss)
    • Waardenburg syndrome (deafness + pigmentation changes)
    • Pendred syndrome (deafness + thyroid issues)
    • Alport syndrome (deafness + kidney disease)
    • Treacher Collins syndrome
    • CHARGE syndrome
  2. Non-syndromic genetic hearing loss (hearing loss is the only symptom):
    • Mutations in genes like GJB2 (connexin 26), GJB6, and others
  3. Autosomal recessive inheritance (most common)
  4. Autosomal dominant inheritance
  5. X-linked inheritance
  6. Mitochondrial inheritance

II. Acquired Causes

These are due to factors after conception and can occur prenatally, perinatally, or postnatally.

A. Prenatal (before birth)

  1. Congenital infections (TORCH):
    • Toxoplasmosis
    • Other (syphilis, varicella-zoster, parvovirus B19)
    • Rubella
    • Cytomegalovirus (CMV)
    • Herpes simplex virus (HSV)
  2. Maternal factors:
    • Diabetes
    • Alcohol or drug use
    • Certain medications (e.g., ototoxic drugs during pregnancy)
    • Hypoxia or lack of oxygen

B. Perinatal (during birth)

  1. Prematurity
  2. Low birth weight
  3. Birth trauma
  4. Neonatal jaundice (hyperbilirubinemia)
  5. Lack of oxygen (anoxia or hypoxia)

C. Postnatal (after birth)

  1. Infections:
    • Meningitis
    • Measles
    • Mumps
    • Chickenpox
    • Ear infections (chronic otitis media)
    • Encephalitis
  2. Ototoxic medications:
    • Aminoglycoside antibiotics (e.g., gentamicin)
    • Chemotherapy drugs (e.g., cisplatin)
    • Loop diuretics
    • Aspirin (at high doses)
  3. Noise exposure:
    • Loud music
    • Firearms
    • Machinery
    • Explosions
  4. Trauma or injury:
    • Skull fractures
    • Barotrauma (e.g., from diving or air travel)
    • Acoustic trauma (sudden loud noise)
  5. Autoimmune inner ear disease
  6. Meniere’s disease (can cause progressive hearing loss)
  7. Tumors:
    • Acoustic neuroma (vestibular schwannoma)
  8. Stroke or other neurological disorders
  9. Aging (Presbycusis) – gradual hearing loss with age

III. Unknown or Idiopathic Causes

In some cases, no identifiable cause can be found for the hearing loss. This is more common in sudden sensorineural hearing loss or in congenital cases with no genetic match.