A 12-month-old girl presents to your office with 1-day history of fever and increasing swelling and redness behind her left ear. On examination, the left auricle is protruding and there is marked erythema, swelling, tenderness, and fluctuance overlying the left mastoid bone (Figure 23-1). Otoscopy reveals a purulent middle ear effusion. A computed tomography (CT) scan of the temporal bones reveals opacification of the mastoid air cells. A diagnosis of acute mastoiditis is made and the girl undergoes urgent myringotomy and tympanostomy tube placement and mastoidectomy. Postoperatively, she is treated with intravenous antibiotics and recovers completely.

Mastoiditis is a complication of otitis media, characterized by a suppurative infection of the mastoid air cells.¹ Acute mastoiditis refers to the finding of acute otitis media on otoscopy in conjunction with local inflammatory findings in the mastoid including erythema, edema, and auricular protrusion, with duration of symptoms less than one month. Coalescent mastoiditis occurs when there is an acute otitis media which progresses into an acute infection of mastoid with osteolytic changes in the bone and destruction of the mastoid air cells. Chronic mastoiditis is defined by the presence of long-standing infection in the presence of tympanic membrane perforation or tympanostomy tube or as a complication of cholesteatoma. Chronic mastoiditis follows an indolent course of infection.

Mastoid inflammation or Mastoid infection.

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  The epidemiology of acute mastoiditis is similar to that of otitis media. Thus, acute and coalescent mastoiditis occurs most frequently in children less than 4 years of age.²

  
  
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  Although recurrent otitis media is a risk factor for mastoiditis, a significant percentage of cases of mastoiditis occur in young children who do not have a prior history of OM.²

  
  
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  Few studies on the incidence of mastoiditis are population based; thus it is difficult to estimate the true incidence and whether the incidence is increasing.

  
  
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  Chronic mastoiditis tends to occur in children with chronic otitis media, chronic otorrhea thru tympanic membrane perforation, and/or cholesteatoma.¹

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  Acute and coalescent mastoiditis may occur in children with well pneumatized mastoids with little or minimal prior history of otitis media.

  
  
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  These acute infections also occur in younger children with more immature immune systems.²

  
  
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  The infectious process usually begins with an acute otitis media that causes edema of the mucoperiosteal lining of the mastoid air cells and middle ear. This blocks the aditus of the mastoid and the Eustachian tube thereby disrupting the normal aeration.^1,3 This leads to worsening purulence and inflammation and eventually development of localized acidosis and bony septa decalcification. In addition, osteoclastic activity cases further destruction of bony septa in the mastoid causing eventual coalescence.

  
  
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  Eventually as the pressure continues to increase in the mastoid, the infection progresses to either intracranial extension or thru lateral cortical bone destruction into the neck and soft tissue postauricularly.

  
  
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  The microbiologic agents responsible for acute and coalescent mastoiditis include Streptococcus pneumoniae, Streptococcus pyogenes, Staphylococcus aureus [including methicillin-resistant strains (MRSA)] and rarely, Pseudomonas aeruginosa.

  
  
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  S pneumoniae serotype 19A, which can be a multidrug resistant organism, has emerged as an important pathogen causing acute mastoiditis.⁴

  
  
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  The microbiology of chronic mastoiditis includes P. aeruginosa, S. aureus (including MRSA), Proteus sp., and anaerobes including Peptostreptococcus, and Bacteroides.

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  Otitis media, young age, and altered immunity are risk factors for mastoiditis.

  
  
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  A history of recurrent otitis media is a risk factor for acute mastoiditis.⁵

  
  
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  Cholesteatoma is a risk factor for chronic mastoiditis.

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  The diagnosis of acute mastoiditis is a clinical diagnosis based on the characteristic clinical findings.⁶

  
  
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  The diagnosis of coalescent mastoiditis can be made in the appropriate clinical setting when osteolytic changes in the bone and destruction of the mastoid air cells are present.

  
  
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  The diagnosis of chronic mastoiditis relies on the presence of a chronic suppurative process and evidence of inflammatory changes in the mastoid.

Clinical Features

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  Postauricular tenderness, erythema, swelling, and fluctuance are the hallmarks of acute mastoiditis.⁷

  
  
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  Protrusion of the auricle is common (Figure 23-2); the displacement is usually downward and outward in young children and upward and outward in older children.

  
  
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  Fever, ear pain, or irritability in younger children may be present.

  
  
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  Otoscopic examination commonly reveals signs of acute otitis media (bulging or erythematous tympanic membrane; Figure 23-3).⁶

Laboratory Testing