What is mastoiditis?

What is Mastoiditis?

Mastoiditis is a bacterial infection of the mastoid air cells (the honeycomb-like bone structure behind the ear) that represents the most common complication of acute otitis media, typically presenting with postauricular swelling, erythema, and tenderness along with fever and otalgia. 1, 2

Clinical Definition and Pathophysiology

Mastoiditis occurs when infection from the middle ear extends into the mastoid air cells, causing suppurative inflammation of these bony structures 1. The condition most commonly affects pediatric patients, particularly those under 2 years of age 2. Streptococcus pneumoniae is the most common causative organism, followed by Streptococcus pyogenes, Haemophilus influenzae, and Staphylococcus aureus 2.

The infection develops as a complication of acute, subacute, or chronic middle ear infections 3. Notably, 33% to 81% of patients diagnosed with acute mastoiditis had been treated with antibiotics prior to admission, indicating that antibiotic treatment for acute otitis media does not eliminate the risk of developing this complication 4.

Clinical Presentation

Key Clinical Features:

• Postauricular erythema and swelling with protrusion of the pinna 1
• Mastoid tenderness on palpation 1
• Tympanic membrane erythema and bulging 1
• External auditory canal swelling 1
• Otorrhea (ear discharge) 1
• Fever and systemic malaise 1

The disease should be suspected in patients who fail treatment for otitis media and demonstrate these examination abnormalities with systemic symptoms 1.

Diagnostic Approach

Clinical Diagnosis

The diagnosis is primarily clinical, based on history and physical examination findings 1, 5. Laboratory analysis may reveal evidence of systemic inflammation with elevated white blood cell count, absolute neutrophil count, and C-reactive protein, though normal inflammatory markers should not be used to exclude the diagnosis 1, 2.

Imaging Considerations

Imaging is not mandatory upon initial presentation in uncomplicated cases 5. According to surveys of otolaryngologists and pediatricians, imaging is performed in less than 50% of hospitalized patients 5.

However, when antibiotic treatment fails and infection persists, symptoms worsen, or new symptoms such as postauricular swelling, mastoid tenderness, headache, vertigo, meningismus, neck rigidity, seizures, or neurological deficits appear, CT temporal bone with IV contrast is the recommended imaging modality 4. CT provides high spatial resolution to assess for intratemporal complications such as coalescent mastoiditis and bony erosion 4.

Classification: Complicated vs Uncomplicated

Uncomplicated Mastoiditis

Uncomplicated mastoiditis should be defined as cases without intracranial complications, subperiosteal abscess, or any evidence of bony erosion including coalescence 6. Using this stricter definition, approximately 36% of cases are truly uncomplicated 6.

Complicated Mastoiditis

Complications can be categorized as:

Extracranial complications: 2

• Subperiosteal abscess (most common)
• Bezold's abscess

Intratemporal complications: 2

• Facial nerve palsy
• Labyrinthitis

Intracranial complications: 4, 2

• Meningitis/encephalitis
• Brain abscess (most common intracranial complication)
• Subdural empyema
• Sigmoid sinus thrombosis
• Seizures

When intracranial complications are clinically suspected, MRI is the preferred imaging method over CT due to its higher sensitivity and specificity 4.

Management Approach

Medical Management

Intravenous antibiotics are the mainstay of treatment for uncomplicated mastoiditis 4, 1. First-line antibiotic choices include:

• Ceftriaxone or cefuroxime (most common, 40-50% of practitioners) 5
• Ampicillin-sulbactam 1

Treatment duration typically ranges from 7 to 10 days 5. Cephalosporins are the antibiotic of choice given the prevalence of Streptococcus pneumoniae 2.

Surgical Considerations

For uncomplicated cases without bony erosion, the trend has shifted toward nonsurgical management with intravenous antibiotics, either alone or combined with myringotomy 4. The success rate of antibiotics alone is approximately 25%, while minor surgical procedures (excluding mastoidectomy) have an 88% success rate 3.

In a contemporary algorithmic approach for uncomplicated cases (without neurologic deficits or sepsis), treatment is initiated with intravenous antibiotics with or without myringotomy. Failure to improve after 48 hours or clinical deterioration should prompt CT scanning to assess for intracranial pathology, followed by mastoidectomy if indicated 4.

For complicated cases:

• Subperiosteal abscess: Can be managed with incision and drainage plus grommet insertion, with good outcomes not requiring subsequent mastoidectomy 7. Some series report successful treatment with needle aspiration and myringotomy in 57% of cases 4
• Sigmoid sinus thrombosis: Managed with IV antibiotics, anticoagulation, and grommet insertion 7
• Mastoidectomy: Reserved for cases with significant bony erosion, treatment failure, or severe complications, with a success rate of 97% 3

Critical Pitfalls

• Do not rely on normal inflammatory markers to exclude mastoiditis 1
• Prior antibiotic treatment does not eliminate risk of mastoiditis development 4
• Otolaryngology consultation is essential 1
• Imaging should be obtained promptly when complications are suspected or when patients fail to improve within 48 hours 4