Related Subjects:
|Brain tumour s
|Astrocytomas
|Brain Metastases
|Tuberous sclerosis
|Turcot's syndrome
|Lhermitte Duclos Disease
|Oligodendroglioma
|Acute Hydrocephalus
|Intracranial Hypertension
|Primary CNS Lymphoma (PCNSL)
|Colloid cyst in the third ventricle
🧠 Brain Abscess: A focal intracranial infection that can mimic a tumour radiologically.
Biopsy or aspiration is often required to confirm diagnosis and guide treatment.
📌 About
- Encapsulated collection of pus within the brain parenchyma.
- Most often caused by Streptococcus (esp. S. milleri group) and Staphylococcus aureus.
- Fungal abscesses are increasingly recognised in immunocompromised patients (e.g. HIV, transplant, steroids, chemotherapy).
- Can arise via direct extension (ENT/dental sepsis), haematogenous spread, or post-trauma/neurosurgery.
⚠️ Risk Factors
- Chronic ear or sinus disease (mastoiditis, sinusitis).
- Dental abscesses, poor oral hygiene.
- Chronic lung disease (bronchiectasis, lung abscess, TB).
- Endocarditis with septic emboli.
- Alcoholism, diabetes, HIV/AIDS, immunosuppressive therapy.
- Skull fracture or penetrating head injury.
🩺 Clinical Features
- Classic triad: Headache, fever, focal neurological deficit (but present in <50%).
- Headache – most common (≈70%).
- Mental status changes → cerebral oedema / raised ICP.
- Seizures (focal or generalised).
- Signs of raised ICP: nausea, vomiting, papilloedema, drowsiness.
- History clues: poor dentition, alcoholism, congenital cyanotic heart disease (esp. children).
- ⚡ Rupture into ventricles → acute meningism, rapid deterioration, high mortality.
🔬 Investigations
- Bloods: ↑ WCC, ↑ CRP/ESR, blood cultures, HIV serology.
- CXR / Echocardiogram: Look for bronchiectasis, lung abscess, or cardiac source.
- CT Brain (contrast): Early = ill-defined low-density cerebritis. Mature abscess = ring-enhancing lesion with surrounding oedema.
- MRI Brain (gadolinium): More sensitive for early changes, multiple/satellite lesions, and cerebritis.
- Lumbar puncture: ❌ Contraindicated if raised ICP (risk of coning).
- Stereotactic aspiration/biopsy: Confirms diagnosis, relieves pressure, provides sample for culture.
💊 Management
- Empirical antibiotics: Start IV broad-spectrum (e.g. cefotaxime/ceftriaxone + metronidazole). Tailor once sensitivities available.
- Stereotactic aspiration/drainage: Diagnostic and therapeutic; reduces mass effect.
- Anticonvulsants: If seizures present or high risk.
- ICP management: Elevate head, mannitol/hypertonic saline if needed.
- Surgery: Consider excision if multiloculated, recurrent, or not responding to antibiotics.
- Neurorehabilitation: For residual neurological deficits.
🌟 Key Clinical Pearls
- Distinguishing from tumour: Both give ring-enhancing lesions, but abscess usually has restricted diffusion on MRI DWI (due to pus).
- Do NOT do LP in suspected abscess unless imaging excludes raised ICP.
- Think of predisposing source: ENT, dental, cardiac, or chest infections.
