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.
H. influenzae, although less common, is the more aggressive agent, more frequently resulting in complications, especially meningitis.
- Streptococcus pneumoniae: most common
- Haemophilus influenzae: common and more aggressive than pneumococcus
- Aspergillus: aggressive; seen in older patients; frequently associated with facial nerve dysfunction
- tuberculous otomastoiditis: increasing frequency due to greater immunocompromised population
CT is the initial investigation of choice. Post-contrast imaging is helpful in assessing for associated soft tissue complications or vascular complications such as dural venous thrombosis.
- partial-to-complete opacification of the mastoid air cells, sometimes of the middle ear cleft as well
- erosion of mastoid air cell bony septum may be present in coalescent mastoiditis
- 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
Typical findings in mastoiditis include 4,5:
- T1: low signal
- T2: high signal
- DWI/ADC: diffusion restriction may be present
- T1 C+: mucosal contrast enhancement is present in the majority
Treatment and prognosis
Usually, antibiotics are all that is required for treatment.
- subperiosteal abscess (mastoid)
- Bezold abscess
- petrous apicitis: extension of infection into a pneumatised petrous apex; ~30% of the population has pneumatised petrous apex 2
- intracranial extension
- facial nerve dysfunction
- thrombosis of mastoid emissary vein ("Griesinger's sign")
- 1. Swartz JD, Harnsberger HR. Imaging of the temporal bone. Thieme Publishing Group. ISBN:3136884035. Read it at Google Books - Find it at Amazon
- 2. Mafee MF, Singleton EL, Valvassori GE et-al. Acute otomastoiditis and its complications: role of CT. Radiology. 1985;155 (2): 391-7. Pubmed citation
- 3. Vazquez E, Castellote A, Piqueras J et-al. RadioGraphics. 2003;23 (2): . doi:10.1148/rg.232025076
- 4. Saat R, Laulajainen-Hongisto AH, Mahmood G et-al. MR imaging features of acute mastoiditis and their clinical relevance. AJNR Am J Neuroradiol. 2014;36 (2): 361-7. doi:10.3174/ajnr.A4120 - Pubmed citation
- 5. Platzek I, Kitzler HH, Gudziol V et-al. Magnetic resonance imaging in acute mastoiditis. Acta Radiol Short Rep. 2014;3 (2): 2047981614523415. doi:10.1177/2047981614523415 - Free text at pubmed - Pubmed citation