Acute Mastoiditis
A serious bacterial infection of the bone behind the ear, usually developing as a complication of an untreated middle ear infection.
Emergency Management: Development of a brain abscess requiring immediate neurosurgical intervention.
Acute mastoiditis is a suppurative infection of the mastoid air cells within the temporal bone. It is the most common suppurative complication of acute otitis media (AOM). The infection leads to inflammation, fluid accumulation, and eventually destruction of the bony septa (coalescent mastoiditis) within the mastoid process.
Detailed Overview
The mastoid air cells connect directly to the middle ear via the aditus ad antrum. Therefore, almost every case of AOM involves some degree of mastoid mucosal inflammation. However, true acute coalescent mastoiditis occurs when pus accumulates under pressure, causing osteitis and breakdown of the bony trabeculae. This can lead to severe intracranial and extracranial complications, including subperiosteal abscess, facial nerve paralysis, sigmoid sinus thrombosis, or meningitis. Prompt recognition and aggressive IV antibiotic therapy, often combined with surgery, are required.
Epidemiology & Demographics
Highest incidence is in children aged 6-24 months. Incidence drastically declined in the post-antibiotic and pneumococcal vaccine eras, currently around 1.2 to 2 cases per 100,000 children.
Etiological Mechanism
Most common organisms are Streptococcus pneumoniae, Streptococcus pyogenes (Group A Strep), and Staphylococcus aureus (including MRSA). Pseudomonas aeruginosa can be seen in chronic cases.
Primary Causes
Untreated or inadequately treated acute otitis media spreading into the contiguous mastoid air cells.
Purulent exudate from AOM enters the mastoid antrum. If the aditus ad antrum becomes blocked by inflamed mucosa, the exudate is trapped. The increasing purulent pressure causes hyperemia and venous stasis, leading to an acidic environment, calcium decalcification, and osteoclastic activity. The thin bony septa separating the mastoid air cells break down, forming a single large cavity filled with pus (coalescent mastoiditis). The pus can track outward through the cortex (forming a postauricular subperiosteal abscess) or inward (causing intracranial complications).
Diagnostic Criteria & Guidelines
Clinical diagnosis based on postauricular erythema, tenderness, and auricular protrusion in the setting of AOM. CT of the temporal bones with contrast is the gold standard to confirm coalescent mastoiditis and rule out complications.
Hospital admission. IV antibiotics: Ceftriaxone 50-75 mg/kg/day IV AND Vancomycin 15 mg/kg IV q6h (to cover MRSA and resistant pneumococcus). Myringotomy +/- tympanostomy tube placement for middle ear drainage is mandatory.
Second-Line & Adjunctive Therapy
For beta-lactam allergy: Clindamycin 40 mg/kg/day IV divided q6h instead of Ceftriaxone, combined with Vancomycin.
Surgical & Procedural Management
Cortical mastoidectomy (drilling out the infected mastoid bone) is indicated if there is a subperiosteal abscess, intracranial complication, or failure to improve after 48 hours of IV antibiotics and myringotomy.
Patient Counseling & Advice
Inform parents that IV antibiotics are required until significant clinical improvement is seen, followed by a prolonged 3-4 week course of oral antibiotics.
Follow-Up & Monitoring Schedule
Close inpatient monitoring for neurological signs (cranial nerve palsies, altered mental status). Outpatient follow-up with audiology to check for conductive hearing loss post-resolution.
Preventive Strategies
Routine pneumococcal conjugate vaccine (PCV15/20) and prompt, appropriate treatment of acute otitis media.
Excellent with prompt IV antibiotics and drainage. Delay in treatment can result in permanent hearing loss or fatal intracranial complications.