Acute mastoiditis

Acute mastoiditis is largely a disease of childhood, and occurs when acute otitis media extends into the mastoid air cells. 

When mastoiditis and acute otitis media occur concurrently, sometimes the term acute otomastoiditis is used. 

When mucoperiosteal involvement evolves into bony involvement, with resorption of mastoid air cell bony septae, the condition should be referred to as coalescent mastoiditis.

It is most frequently due to bacterial infections, with Streptococcus pneumoniae and Haemophilus influenzae accounting for 65-80% of cases. 

H. influenzae, although less common, is the more aggressive agent and more frequently resulting in complications, especially meningitis.

Aetiology

CT is the initial investigation of choice. Post contrast imaging helpful in assessing for associated soft tissue complications or vascular complications such as dural venous thrombosis. 

CT
  • partial-to-complete opacification of the mastoid air cells +/- middle ear cleft
  • erosion of mastoid air cell bony septum may be present in coalescent mastoiditis
MRI
  • partial-to-complete opacification of the mastoid air cells +/- middle ear cleft
  • fluid signal intensity in the mastoid should not be interpreted as mastoiditis without other evidence such as mucosal contrast enhancement and/or diffusion restriction 5
Signal characteristics

Typical findings in mastoiditis include 4,5:

  • T1: low signal
  • T2: high signal
  • DWI/ADC: diffusion restriction may be present
  • T1C+: mucosal contrast enhancement is present in the majority

Usually antibiotics are all that is required for treatment. 

Complications
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Article Information

rID: 857
System: Head & Neck
Section: Pathology
Synonyms or Alternate Spellings:
  • Acute otomastoiditis

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