What are the potential complications of untreated mastoiditis, particularly in children and immunocompromised individuals?

Complications of Untreated Mastoiditis

Untreated mastoiditis can lead to life-threatening intracranial complications including meningitis, brain abscess, sigmoid sinus thrombosis, subdural empyema, and extracranial complications such as subperiosteal abscess and facial nerve paralysis, with intracranial complications occurring in approximately 21-28% of cases and carrying a mortality rate of 14-36% depending on the specific complication. 1, 2, 3, 4, 5

Extracranial Complications

Subperiosteal abscess is the most common extracranial complication, occurring in approximately 28-90% of complicated mastoiditis cases 3, 5. This presents clinically as:

• Mastoid tenderness and retroauricular swelling 1
• Protrusion of the auricle 1
• Visible fluctuant mass behind the ear 3

Facial nerve paralysis occurs in up to 25-40% of complicated cases, representing a serious intratemporal complication requiring urgent intervention 3, 5.

Intracranial Complications

Intracranial complications develop in 21-28% of acute mastoiditis cases and represent the most dangerous sequelae 2, 3, 5. These include:

Brain Abscess

• Most common intracranial complication overall, with an incidence of approximately 1 per million per annum in the general population 2
• Carries the highest mortality rate at 36% among intracranial complications 4
• Cerebellar abscess is particularly associated with chronic mastoiditis 6, 5

Meningitis

• Occurs in 17-37% of complicated mastoiditis cases 3, 4, 5
• May present with headache, meningismus, neck rigidity, and altered consciousness 1, 7

Sigmoid Sinus Thrombosis

• Develops in 7-17% of complicated cases 6, 3, 5
• May present as Symonds Syndrome (classic triad of headache, papilledema, and sixth nerve palsy) 6
• Children with mastoiditis are at particularly high risk for venous sinus thrombosis 7
• Can occur postoperatively even after aggressive treatment 8

Other Intracranial Complications

• Epidural abscess occurs in approximately 14% of complicated cases 4, 8
• Subdural empyema is less common but highly morbid 1, 7
• Perisigmoid abscess may accompany sigmoid sinus thrombosis 6, 3
• Labyrinthitis can lead to permanent hearing loss and vestibular dysfunction 1, 2

Critical Clinical Warning Signs

The American College of Radiology emphasizes that specific clinical signs suggest life-threatening complications 1:

• Headache, vertigo, or seizures
• Meningismus or neck rigidity
• Neurological deficits or altered consciousness
• Persistent high fever despite 48 hours of IV antibiotics 2, 7
• Persistent otalgia and otorrhea 3

Special Populations at Higher Risk

Children

• 74% of intracranial complications occur in children and young adults 4
• Highest incidence in children aged 1-4 years 2
• More likely to develop sigmoid sinus thrombosis 7
• Overall mortality rate of 14% for intracranial complications in pediatric series 4

Immunocompromised Individuals

While the evidence does not specifically address immunocompromised patients in detail, the general principles suggest these patients would be at higher risk for:

• More rapid progression to complications 1
• Polymicrobial or atypical infections 3
• Higher failure rates with conservative management 7

Asymptomatic Complications

A critical pitfall is that intracranial complications may be asymptomatic 8. In one series, 8 of 11 pediatric patients (73%) had asymptomatic intracranial complications identified only on CT imaging, including sigmoid sinus thrombosis and epidural abscess 8. This underscores that no reliable clinical signs distinguish patients with coexistent intracranial complications, making imaging crucial 7.

Mortality and Morbidity

• Overall mortality from intracranial complications: 14% 4
• Brain abscess mortality: 36% (highest among complications) 4
• Increased mortality correlates directly with neurological status on hospital admission 6
• Long-term neurological and psychiatric sequelae can occur even with successful treatment 6

Diagnostic Imperative

CT temporal bone with IV contrast is essential when mastoiditis fails to improve after 48 hours of treatment or shows clinical deterioration, as it detects bone erosion, coalescence of air cells, and soft tissue complications 1, 2, 7. MRI with contrast is superior for detecting intracranial complications including meningitis, brain abscess, and dural venous sinus thrombosis 1, 7.

Common Pitfalls

• Prior antibiotic treatment does not prevent mastoiditis or its complications—33-81% of mastoiditis patients had received antibiotics before diagnosis 1, 7
• Relying solely on clinical examination may miss asymptomatic intracranial complications 8
• Delaying imaging in non-resolving cases increases morbidity and mortality 1, 7