Description

• Inflammatory process of the mastoid bone
• Acute mastoiditis is a suppurative infection that typically presents after acute otitis media. Symptoms are present for <1 month. Subdivided into 2 stages:
  • Acute mastoiditis with periosteitis: Involvement of the periosteum of the mastoid bone, purulence within the mastoid air cells
  • Acute mastoid osteitis (coalescent mastoiditis): Destruction of the bony septae that separate air cells; leads to an empyema and involvement of more serious head and neck complications
• Subacute mastoiditis (masked mastoiditis): Indolent process, may occur with recurrent AOM that was not sufficiently treated
• Chronic mastoiditis: Due to chronic suppurative otitis media that has failed treatment; usually associated with cholesteatoma; symptoms lasting months to years

Epidemiology

• Children > Adults
• Most common in children <2 years of age
• In pediatrics: Males > Females
• Incidence down since introduction of antibiotics; controversial whether incidence is now rising due to antibiotic-resistant Staphylococcus pneumoniae

Incidence
1–4 cases/100,000/yr (1)

Risk Factors

• Cholesteatoma
• Recurrent acute otitis media or chronic suppurative otitis media
• Immunocompromised patient

Genetics
No known genetic pattern

General Prevention

• Adequate antibiotic treatment for acute otitis media
• Prevention of recurrent acute otitis media
• Early referral to ENT for chronic otitis media
• Treatment of chronic eustachian tube dysfunction (i.e., pressure equalization tubes)
• Early identification of cholesteatoma
• Pneumococcal conjugate vaccine

Pathophysiology

• Subclinical stage begins with acute otitis media causing inflammation of mastoid air cells (likely present in all cases of AOM).
• Obstruction of the aditus ad antrum (the connection between the tympanic cavity and the mastoid) during severe cases of AOM:
  • Blocks outflow tract of mastoid air cells
  • Accumulation of edema and purulent material with penetration of mucosa and 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 then lead to pus dissecting to adjacent areas in head and neck and subsequent abscess formation:
  • Subperiosteal abscess (most common complication), Bezold abscess, suppurative labyrinthitis, suppurative CNS complications

Etiology

• AOM: Haemophilus influenzae, Streptococcus pneumoniae
• Acute mastoiditis: S. pneumoniae (most common organism), Streptococcus pyogenes, Haemophilus influenzae, Staphylococcus aureus (including methicillin-resistant S. aureus [MRSA]):
  • Introduction of the 7-valent pneumococcal conjugate vaccine in 2000 has led to increase in multidrug-resistant S. pneumoniae serotype 19A.
• Chronic mastoiditis: Pseudomonas aeruginosa, S. aureus, Enterobacteriaceae, anaerobic bacteria, polymicrobials (2)