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Acute mastoiditis refers to a suppurative infection of the mastoid air cells. It is the most common complication of acute otitis media.
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In acute otitis media, an inflammatory middle ear effusion is present that can freely move into the mastoid air cells. Consequently, some authors comment that a mild mastoiditis is technically present in nearly all cases of acute otitis media 6. The mere presence of mastoid fluid on imaging, however, does not change the management of otherwise uncomplicated acute otitis media. Thus, many clinicians reserve the diagnosis for when there are clinical signs or symptoms of inflammation involving the mastoid. When mastoiditis and acute otitis media occur concurrently, sometimes the term "acute otomastoiditis" is used.
When there is clinical evidence of acute mastoiditis, the initial stage is referred to as "acute mastoiditis with periostitis", "incipient mastoiditis", or "mild mastoiditis" 6,7. When mucoperiosteal involvement evolves into resorption of mastoid bony septa, this stage is referred to as coalescent mastoiditis. Coalescent mastoiditis is a radiological diagnosis.
Acute mastoiditis, like acute otitis media, is largely a disease of childhood.
Acute mastoiditis characteristically presents with postauricular tenderness, erythema, and swelling causing protrusion of the auricle. Common non-specific findings include otalgia and fever. Abscesses may present with fluctuance or a palpable mass.
Acute mastoiditis with periostitis is pathologically characterized by spread of infection through the mastoid emissary veins into the periosteum. Acute coalescent mastoiditis is characterized by infiltration and destruction of the bone, essentially osteomyelitis.
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, 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 or intracranial complications.
partial-to-complete opacification of the mastoid air cells, which is non-specific but supportive of incipient mastoiditis in the appropriate clinical setting
erosion of mastoid air cell bony septa, which establishes the diagnosis of coalescent mastoiditis
erosion of the lateral wall of the mastoid, suggestive of subperiosteal abscess, or of the sigmoid plate, suggestive of epidural abscess
mass with surrounding fat stranding or rim-enhancing collection deep to the sternocleidomastoid muscle, suggestive of Bezold abscess, or within the digastric triangle, suggestive of Citelli abscess
erosion indicating osteomyelitis of the petrous apex (petrous apicitis, petrositis) or occipital bone (confusingly also known as Citelli abscess)
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+ (Gd): mucosal contrast enhancement is present in the majority
Treatment and prognosis
Usually, antibiotics are all that is required for treatment.
petrous apicitis: extension of infection into a pneumatized petrous apex; ~30% of the population has pneumatized petrous apex 2
epidural abscess, most commonly perisinus (adjacent to sigmoid sinus)
facial nerve dysfunction
thrombosis of mastoid emissary vein (Griesinger sign)
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- 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, Mauleon S, Creixell S, Pumarola F, Figueras C, Carreño JC, Lucaya J. Imaging of complications of acute mastoiditis in children. (2003) Radiographics : a review publication of the Radiological Society of North America, Inc. 23 (2): 359-72. doi:10.1148/rg.232025076 - Pubmed
- 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
- 6. McDonald MH, Hoffman MR, Gentry LR. When is fluid in the mastoid cells a worrisome finding?. (2013) Journal of the American Board of Family Medicine : JABFM. 26 (2): 218-20. doi:10.3122/jabfm.2013.02.120190 - Pubmed
- 7. Vazquez E, Castellote A, Piqueras J, Mauleon S, Creixell S, Pumarola F, Figueras C, Carreño JC, Lucaya J. Imaging of complications of acute mastoiditis in children. (2003) Radiographics : a review publication of the Radiological Society of North America, Inc. 23 (2): 359-72. doi:10.1148/rg.232025076 - Pubmed