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Emergency and Acute Medicine – Mastoiditis
Basics description
Mastoiditis is inflammation of the mastoid air cells of the temporal bone, most commonly resulting from direct extension of acute purulent otitis media. The middle ear and mastoid air cells communicate through the aditus to the mastoid antrum. In otitis media, inflammatory obstruction of this channel leads to fluid trapping, creating an environment for infection. Clinical manifestations range from mild inflammation of mastoid air cells to aggressive infection with bone destruction and serious intracranial or extracranial complications.
Acute mastoiditis occurs to some degree in all cases of otitis media, with early signs indistinguishable from acute otitis media. As infection progresses, involvement of the periosteum causes periostitis, which may be associated with a subperiosteal abscess. Further progression leads to acute mastoid ostitis (coalescent mastoiditis), characterized by destruction of mastoid trabeculae and coalescence of air cells, sometimes with mastoid empyema or a draining fistula. Untreated disease may result in severe head and neck or intracranial complications.
Masked mastoiditis refers to persistent mastoid infection after partial treatment of otitis media, which may later progress to acute or coalescent mastoiditis. Chronic mastoiditis is defined as infection lasting longer than 3 months. Mastoiditis may also complicate systemic conditions such as leukemia, infectious mononucleosis, sarcoma of the temporal bone, HIV, or Kawasaki disease. Although less common in the antibiotic era, it remains more frequent in infants and young children.
Etiology
Pathogens are similar to those causing otitis media but differ in prevalence. Common organisms in acute mastoiditis include Streptococcus pneumoniae, group A streptococcus, Staphylococcus aureus, and Haemophilus influenzae. Chronic mastoiditis more often involves gram-negative enteric organisms such as Pseudomonas aeruginosa, Escherichia coli, Proteus mirabilis, and Bacteroides species. Less common causes include Mycobacterium tuberculosis and Aspergillus species in immunocompromised patients. In children, S. pneumoniae remains the most frequent pathogen.
Diagnosis signs and symptoms
Patients commonly present with ear pain, otorrhea, fever, headache, and hearing loss of varying severity. Children may show irritability and a history of recurrent otitis media. Physical examination typically reveals postauricular tenderness, edema, and erythema; lateral and inferior displacement of the auricle; loss of the postauricular crease; swelling of the posterior and superior ear canal wall; and tympanic membrane abnormalities consistent with severe otitis media, including bulging or purulent drainage.
Essential workup and diagnostic testing
Mastoiditis is primarily a clinical diagnosis. Laboratory studies may show leukocytosis. Cultures of otorrhea or surgical drainage are important because of pathogen diversity, and blood cultures should be obtained in toxic-appearing patients. Imaging supports diagnosis and evaluates complications: plain mastoid radiographs may show haziness or opacification but have low sensitivity. CT of the temporal bone is more useful, especially for detecting abscesses, trabecular destruction, and complications. MRI is reserved for suspected intracranial involvement not clarified by CT. Lumbar puncture is indicated if meningitis is suspected. In children, judicious use of CT is recommended to minimize radiation exposure when clinical diagnosis is clear.
Differential diagnosis
Otitis media, cellulitis, otitis externa, scalp infection with posterior auricular lymphadenitis, rubella, trauma to the pinna or postauricular area, and meningitis.
Treatment and emergency management
Initial management follows standard ABCs, with IV fluids for hypotension or dehydration. Prompt initiation of IV antibiotics is essential. Given the increasing role of S. aureus, empiric regimens should include antistaphylococcal coverage until culture results are available, with consideration of antipseudomonal coverage in chronic disease. Otolaryngology consultation is mandatory. Surgical drainage is the definitive therapy for acute or coalescent mastoiditis and is emergent in toxic patients. Procedures may include myringotomy with tympanostomy tube placement or mastoidectomy with drainage, required in approximately half of cases. Analgesia with NSAIDs or opioids should be provided.
Disposition and follow-up
All patients with suspected acute or coalescent mastoiditis require admission. Discharge is not appropriate in these cases. Otolaryngology follow-up is essential, and audiography should be performed after resolution to assess for hearing loss.
Complications
Potential complications include Bezold abscess, petrositis, calvarial osteomyelitis, subperiosteal abscess, subdural empyema, and dural venous sinus thrombosis.
Key points and pitfalls
Maintain a high index of suspicion in patients with persistent or inadequately treated otitis media. Failure to recognize meningitis or intracranial extension is a major pitfall. Definitive management requires timely surgical drainage in addition to antibiotics.
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