• Inflammation of the mastoid air cells of the temporal bone, generally caused by direct extension of acute purulent otitis media
  • Middle ear and mastoid air cells are contiguous via the aditus to mastoid antrum
  • Fluid accumulation from closure of channel due to otitis media creates opportunity for infection
  • Manifestation ranges from clinically insignificant inflammation of mastoid air cells to infection and destruction of the bone
  • Acute mastoiditis:
    • Occurs to some degree in all cases of otitis media
    • Early signs and symptoms are those of acute otitis media
    • Usually secondary to contamination with infectious material trapped in the mastoid by inflammatory obstruction of the channel between middle ear and mastoid air cells
  • Acute mastoiditis with periostitis:
    • As infection progresses, periosteum of the mastoid bone is involved, causing periostitis
    • Subperiosteal abscess may be present
  • Acute mastoid ostitis (also called coalescent mastoiditis):
    • Progression of the infection within the mastoid air cells leads to destruction of the mastoid trabeculae, causing coalescence of bony trabeculae
    • Mastoid empyema or a draining fistula may be present
    • May progress to severe head and neck complications if untreated
  • Masked mastoiditis:
    • Mastoid infection, which lingers after an acute otitis media has been treated
    • May progress to acute or coalescent mastoiditis
  • Chronic mastoiditis:
    • Infection lasting >3 mo
  • Mastoiditis can be a complication of a primary disorder:
    • Leukemia
    • Mononucleosis
    • Sarcoma of the temporal bone
    • HIV
    • Kawasaki disease
  • Mastoiditis more common prior to the use of antibiotics for acute otitis media
  • More common in young children and infants


  • Organisms in acute mastoiditis are similar to those in acute otitis media, but differ in frequency:
    • Streptococcus pneumoniae
    • Group A streptococcus
    • Staphylococcus aureus
    • Haemophilus influenzae
  • Gram-negative enteric bacteria most common with chronic mastoiditis:
    • Pseudomonas aeruginosa
    • Escherichia coli
    • Proteus mirabilis
    • Bacteroides species
  • Other less common causes:
    • Mycobacterium tuberculosis
    • Aspergillus species in immunocompromised states

Pediatric Considerations
  • More frequently seen in the pediatric population due to strong association with otitis media
  • S. pneumoniae is the most common cause in children

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