Brain abscess
Brain abscess is a focal, ring-enhancing suppurative infection of the brain parenchyma most often from contiguous sinus, ear, or dental spread or hematogenous seeding, diagnosed by contrast MRI and image-guided aspiration and treated with predisposing-source-directed empiric antibiotics plus drainage of abscesses larger than 2.5 cm.
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What this article covers
- Overview
A focal, suppurative infection of the brain parenchyma: brain abscess forms a purulent, encapsulated collection that most commonly arises from contiguous spread of a nearby infection or from hematogenous seeding.
- Epidemiology
Can occur at any age but is most common in men.
- Risk factors
Contiguous infection: sinusitis, otitis media, mastoiditis, or dental sepsis: the leading predisposing condition, accounting for about half of cases.
- Pathophysiology
Organisms reach the brain parenchyma by contiguous extension, hematogenous seeding, or direct inoculation: contiguous spread from sinus, ear, or dental infection tends to produce a single lesion in…
- Clinical features
Headache is the most common presenting symptom: typically severe, progressive, and not relieved by analgesics, localizing to the side or region of the abscess.
- Differential diagnosis
Bacterial meningitis: headache and fever with nuchal rigidity and a positive Kernig/Brudzinski sign are more prominent; focal deficits and mass lesion are absent, and lumbar puncture (if safe) shows…
- Diagnosis
First, confirm the diagnosis with neuroimaging: obtain MRI with contrast (preferred) or CT with contrast if MRI is unavailable, before any lumbar puncture, because a mass lesion with elevated…
- Management
First, obtain urgent neuroimaging and assess abscess size and mass effect; do not perform lumbar puncture if a focal deficit or mass lesion is present.
- Complications
Brain herniation: the most immediately life-threatening complication from mass effect and raised intracranial pressure; the reason lumbar puncture is avoided when a mass lesion is suspected.
- Prognosis
Outcome is driven by how quickly the abscess is drained (when indicated) and appropriate antibiotics are started: delay increases the risk of permanent neurologic deficit and death.
- Prevention
Prompt, adequate treatment of predisposing infections (sinusitis, otitis media, mastoiditis, dental sepsis) before they progress to intracranial extension.
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