Synopsis
Recognise a focal intracranial infection, avoid hazardous lumbar puncture, identify the likely source, and coordinate urgent imaging, neurosurgical microbiology and prolonged organism-directed therapy.
- Brain abscess evolves from focal cerebritis into a capsule containing pus; symptoms reflect location, oedema and raised intracranial pressure as much as systemic infection.
- Headache, focal deficit, seizure, cognitive change and fever are common components, but the classic triad of fever, headache and focal neurology is absent in many cases.
- Contiguous spread follows chronic otitis or mastoiditis, sinus or dental infection, while haematogenous spread can arise from endocarditis, lung infection, right-to-left cardiac shunt or injected drug use.
Key red flags
Falling consciousness, unequal pupils, extensor posturing, bradycardia with hypertension or progressive vomiting indicates dangerous mass effect and needs immediate critical-care and neurosurgical action.
Investigation priorities
Define lesion number, site, capsule, pus characteristics, oedema and ventricular proximity.
Management branches
Progressive headache, seizure or focal deficit occurs with an infection source or immune risk.
- Stabilise airway and circulation, treat seizures and obtain urgent contrast CT or MRI while checking for raised-pressure signs and avoiding lumbar puncture.
- Contact neurosurgery and infection specialists as soon as imaging suggests abscess, arranging transfer to a centre able to drain and monitor intracranial complications.
Key medicines
CeftriaxoneUse the current local central-nervous-system infection dose intravenously, commonly 2 g twice daily in adults, with infection-specialist confirmation and renal or hepatic context.
MetronidazoleA common adult intravenous or oral regimen is 500 mg every 8 hours, but route and duration must follow the abscess protocol and microbiological findings.