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.
- Contrast-enhanced MRI is the preferred definitive intracranial staging test; it detects small posterior-fossa, cortical and leptomeningeal lesions better and guides surgery or stereotactic radiotherapy.
- Restage extracranial disease and review the primary histology and molecular profile because systemic options and expected survival shape intracranial treatment.
- A solitary or atypical lesion, unknown primary, long cancer-free interval or discordant systemic picture often needs surgical or stereotactic biopsy before irreversible treatment.
- First-line symptomatic treatment for clinically important vasogenic oedema is dexamethasone at the lowest effective dose, with a planned taper after surgery, radiation or systemic response.
- Do not give routine corticosteroid to every asymptomatic small metastasis, because hyperglycaemia, infection, myopathy, delirium and reduced immunotherapy efficacy can outweigh benefit.
- Treat a tumour-related seizure with a low-interaction antiseizure medicine; do not prescribe prophylactic antiseizure medication indefinitely to a patient who has never seized.
- Surgical resection is preferred for selected large, accessible, symptomatic solitary or dominant lesions, particularly when tissue, decompression and rapid neurological improvement are needed.
- Stereotactic radiosurgery or fractionated stereotactic radiotherapy provides high local control for limited lesions or selected total intracranial volume and for many postoperative cavities.
- Whole-brain radiotherapy is reserved for selected extensive disease or situations unsuitable for focal treatment; discuss expected intracranial benefit against fatigue, alopecia and cognitive harm.
- CNS-active systemic treatment may be central in targetable lung cancer, HER2-positive breast cancer and melanoma, but symptomatic local mass effect usually needs prompt local therapy rather than waiting for systemic response.
- Management is based on performance, neurological function, lesion number and volume, extracranial control, molecular options, prognosis and patient goals—not lesion count alone.
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.
Progressive headache with vomiting, papilloedema, drowsiness or sixth-nerve palsy suggests raised intracranial pressure rather than an ordinary treatment side effect.
Falling consciousness, unequal pupils, abnormal posturing or Cushing physiology indicates impending herniation and needs immediate neurosurgical escalation.
A cerebellar or posterior-fossa metastasis can obstruct cerebrospinal fluid abruptly and may need urgent resection or diversion even when extracranial disease is present.
Melanoma, renal, thyroid and choriocarcinoma metastases can bleed; a sudden severe headache or deficit requires emergency non-contrast CT.
Cranial neuropathies, radicular pain, multifocal neurological signs or headache with a near-normal scan raises leptomeningeal disease and requires dedicated MRI and selected CSF assessment.
Do not attribute neurological change to opioids, infection or metabolic disturbance until intracranial progression, haemorrhage and seizure have been considered in parallel.
Investigation priorities
Identify acute haemorrhage, major oedema, hydrocephalus and shift rapidly when consciousness, seizure or focal function deteriorates.
Define lesion number, total volume, posterior-fossa and meningeal involvement, surgical anatomy and stereotactic targets.
Management branches
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.
- After stabilisation, obtain contrast MRI, systemic staging and tissue where needed and replace an indefinite steroid course with a definitive local and systemic plan.