Mastoiditis is an inflammatory process of the mastoid bone. It is most commonly seen as a complication of acute otitis media (AOM).


  • Clinical manifestations of mastoiditis typically appear days to weeks after the first middle ear symptoms.
  • Subdivided according to pathologic stage:
    • Acute mastoiditis with periostitis (incipient mastoiditis): purulent material in the mastoid cavities; symptom duration typically ≤1 month
    • Coalescent mastoiditis (acute mastoid osteitis): destruction of the thin bony septae between air cells; followed by the formation of abscess cavities with pus dissecting into adjacent areas
  • Masked mastoiditis (subacute mastoiditis): low grade, persistent infection with destruction of the bony septae between air cells; occurs in patients with persistent middle ear effusion or recurrent episodes of inadequately treated AOM
  • Chronic mastoiditis: associated with failed treatment of chronic otitis media; often associated with cholesteatoma; symptoms last for months to years.


Highest incidence in children aged <2 years

  • Similar to population susceptible to AOM (male, daycare attendance)
  • Less common if immunizations up-to-date and antibiotics used to treat suppurative AOM

1.2 to 3.8 cases per 100,000 children per year in the United States (1)

Etiology and Pathophysiology

  • Subclinical stage begins with AOM and inflammation of mastoid air cells.
  • Mastoid is part of petrous temporal bone composed of air-filled cells.
  • Mastoid aditus and antrum form a narrow connection between middle ear and mastoid air cells.
    • Fluid in the middle ear can cause obstruction at aditus or antrum, blocking outflow tract of mastoid air cells.
    • Edema and accumulation of purulent material most commonly spreads from mastoid air cells to periosteum via mastoid emissary veins with penetration of periosteum (acute mastoiditis with periosteitis).
  • Increased pressure from fluid within the air cells leads to destruction of bony septae (acute mastoid osteitis/acute coalescent mastoiditis).
  • Acute mastoid osteitis can spread to adjacent areas in head and neck with abscess formation:
    • Subperiosteal abscess (most common complication), Bezold abscess, suppurative labyrinthitis, suppurative CNS complications (2)
  • AOM: Streptococcus pneumoniae, nontypeable Haemophilus influenzae
  • Acute mastoiditis: S. pneumoniae (most common), group A streptococci—Streptococcus pyogenes, Staphylococcus aureus (including methicillin-resistant S. aureus [MRSA]), H. influenzae, Fusobacterium necrophorum
  • Chronic mastoiditis: Pseudomonas aeruginosa, S. aureus, anaerobic bacteria, polymicrobials (organisms present in external ear canal), rarely Mycobacterium tuberculosis
  • Abscess: S. aureus, mycobacteria, Aspergillus
  • Increased incidence of penicillin-resistant S. pneumoniae infections has gradually lead to higher incidence of mastoiditis as complication of AOM.

No known genetic pattern

Risk Factors

  • Cholesteatoma appears as squamous pearl in anterosuperior area of middle ear near tympanic membrane.
  • Recurrent AOM or chronic suppurative otitis media
  • Immunocompromised state

General Prevention

  • Ensure immunizations (particularly pneumococcal vaccine) are up-to-date.
  • Referral to ENT for chronic otitis media
  • Appropriate diagnosis and treatment of AOM; prevent recurrent AOM.
    • Chemoprophylaxis for AOM is controversial. Historically, consider in children with two episodes of AOM in first 6 months of life or in older children, three episodes in 6 months, or four episodes in 1 year. Chemoprophylaxis is not currently recommended by American Academy of Pediatrics due to concern for multidrug resistance.
  • Wear ear plugs when swimming or showering to keep water out of the ears with AOM.
  • Treat chronic eustachian tube dysfunction (pressure equalization tubes).
  • Early diagnosis of cholesteatoma

Commonly Associated Conditions


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