Educational draft · awaiting clinical reviewUse Rapid for revision, not patient-care decisions. Check current national and local guidance and the BNF or BNFC before acting.
2 min synopsisUK scopeSources checked 27 Aug 2026Clinical review pending
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Herniation, obstructive hydrocephalus or uncontrolled seizure
Reduced consciousness, new pupillary asymmetry, rapidly progressive deficit, repeated vomiting with severe mass effect, a posterior-fossa lesion obstructing CSF or status epilepticus requires immediate treatment before complete oncological staging.
Action: Use ABCDE care, protect oxygenation and cerebral perfusion, elevate the head, treat seizures and obtain urgent CT while contacting neurosurgery and acute oncology. Give dexamethasone promptly for clinically significant tumour-related vasogenic oedema and arrange emergency decompression, resection or CSF diversion when anatomy and prognosis support it.
Synopsis
Recognise neurological metastatic disease and dangerous mass effect, define intracranial number, volume and anatomy with contrast MRI, establish or confirm the primary cancer and integrate surgery, stereotactic radiotherapy, systemic treatment, corticosteroid, seizure and supportive care.
Brain metastases are more common than malignant primary brain tumours and most often arise from lung, breast, melanoma, renal and colorectal cancers.
Presentation includes headache, focal deficit, seizure, cognitive or personality change, ataxia and occasionally haemorrhage or an incidental staging-scan finding.
Emergency non-contrast CT is first line for acute deterioration because it rapidly identifies haemorrhage, hydrocephalus and dangerous mass effect.
Key red flags
A first seizure, focal weakness, aphasia, visual loss, ataxia or personality change in a patient with current or previous cancer requires urgent brain imaging.
Posterior-fossa syndrome
Gait ataxia, vertigo, dysarthria, nystagmus, vomiting and cranial-nerve signs can precede acute hydrocephalus and require urgent neurosurgical review.
Investigation priorities
01
Emergency non-contrast CT brainFirst step
Identify acute haemorrhage, major oedema, hydrocephalus and shift rapidly when consciousness, seizure or focal function deteriorates.
02
Preferred contrast MRI brainPreferred
Define lesion number, total volume, posterior-fossa and meningeal involvement, surgical anatomy and stereotactic targets.
Management branches
Acute neurological declineControl oedema and mass effect first
A patient with known or possible cancer develops reduced consciousness, progressive deficit, severe vomiting or seizure.
Use ABCDE care, check glucose and reversible metabolic causes, treat seizure, elevate the head and obtain emergency non-contrast CT while contacting acute oncology and neurosurgery.
Give dexamethasone for significant tumour-related oedema and use urgent resection or CSF diversion for a suitable large lesion, haemorrhage, posterior-fossa obstruction or hydrocephalus.
Key medicines
Dexamethasone for symptomatic oedemaUse the lowest effective oral or intravenous dose, commonly 4 to 8 mg daily for moderate symptoms and up to 16 mg daily in divided doses for severe mass effect, then taper promptly after definitive control.
Levetiracetam after a metastatic seizureStart commonly at 500 mg orally twice daily and titrate according to recurrent seizures, tolerability and renal function, with intravenous equivalent during acute inability to swallow.
National guidance is shown before implementation-dependent detail. Typical adult dose examples remain subject to patient factors, contraindications and the live BNF or specialist protocol. Source check completed 27 Aug 2026; clinical approval remains outstanding.