Dx: Acute mastoiditis with epidural abscess
The contrast-enhanced cranial MRI scan (FIGURE 1A) revealed a case of acute mastoiditis with fluid in the left mastoid (blue arrow) and a large epidural abscess in the left posterior fossa (green arrow). The normal right mastoid was air-filled (yellow arrow). The T2-weighted MRI scan (FIGURE 1B) showed mild dilatation of the lateral ventricles (blue arrow) secondary to compression on the fourth ventricle by mass effect from the epidural abscess.
Acute mastoiditis—a complication of AOM—is an inflammatory process of mastoid air cells, which are contiguous to the middle ear cleft. In one large study of 61,783 inpatient children admitted with AOM, acute mastoiditis was reported as the most common complication in 1505 (2.4%) of the cases.1 The 2000-2012 national estimated incidence rate of pediatric mastoiditis has ranged from a high of 2.7 per 100,000 population in 2006 to a low of 1.8 per 100,000 in 2012.2 Clinical features of mastoiditis include localized mastoid tenderness, swelling, erythema, fluctuance, protrusion of the auricle, and ear pain.3
The clinical presentation of epidural abscess can be subtle with fever, headache, neck pain, and changes in mental status developing over several days.1 Focal deficits and seizures are relatively uncommon. In a review of 308 children with acute mastoiditis (3 with an epidural abscess), high-grade fever and high absolute neutrophil count and C-reactive protein levels were associated with the development of complications of mastoiditis, including hearing loss, sinus venous thrombosis, intracranial abscess, and cranial nerve palsies.4
Venous sinus thrombosis was part of the differential
When we were caring for this patient, the differential diagnosis included a cranial extension of AOM. Venous sinus thrombosis was also considered, given the family history of a hypercoagulable state. The patient did not have any features suggesting primary headache syndromes, such as migraine, tension type, or cluster headache.
The differential for a patient complaining of ear pain also includes postauricular lymphadenopathy, mumps, periauricular cellulitis (with and without otitis externa), perichondritis of the auricle, and tumors involving the mastoid bone.4
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