In acute purulent otitis media, inflammation often extends into the mastoid antrum and air cells in the temporal bone, resulting in fluid accumulation. In a few patients, bacterial infection develops in the collected fluid, typically with the same organism causing the otitis media; pneumococcus is most common. Mastoid infection can cause osteitis of the septae, leading to coalescence of the air cells.
The infection may decompress through a perforation in the tympanic membrane or extend through the lateral mastoid cortex, forming a postauricular subperiosteal abscess. Rarely, it extends centrally, causing a temporal lobe abscess or a septic thrombosis of the lateral sinus. Occasionally, the infection may erode through the tip of the mastoid and drain into the neck (called a Bezold abscess).
Symptoms begin days to weeks after onset of acute otitis media and include fever and persistent, throbbing otalgia. Nearly all patients have signs of otitis media and purulent otorrhea. Redness, swelling, tenderness, and fluctuation may develop over the mastoid process; the pinna is typically displaced laterally and inferiorly.
Diagnosis is clinical. CT is rarely necessary but can confirm the diagnosis and show the extent of the infection. Any middle ear drainage is sent for culture and sensitivity. Tympanocentesis for culture purposes can be done if no spontaneous drainage occurs. Complete blood count (CBC) and erythrocyte sedimentation rate (ESR) may be abnormal but are neither sensitive nor specific and add little to the diagnosis.
IV antibiotic treatment is initiated immediately with a drug that provides central nervous system penetration, such as ceftriaxone 1 to 2 g (children, 50 to 75 mg/kg) once a day continued for ≥ 2 weeks; vancomycin or linezolid are alternatives. Oral treatment with a quinolone may be acceptable. Subsequent antibiotic choice is guided by culture and sensitivity test results.
A subperiosteal abscess usually requires a simple mastoidectomy, in which the abscess is drained, the infected mastoid cells are removed, and drainage is established from the antrum of the mastoid to the middle ear cavity.