Headache: differential diagnosis

Headache: differential diagnosis
No signs on examination
Tension headache
Migraine
Cluster headache
Post-traumatic
Drugs (nitrates, calcium channel antagonists)
Carbon monoxide poisoning or anoxia

Signs of meningism?
Meningitis (may not have fever or rash)
Subarachnoid haemorrhage (examination may be normal)

Decreased conscious level or localizing signs?
Encephalitis/meningitis
Stroke
Cerebral abscess
Subarachnoid haemorrhage
Tumour
Subdural haematoma
TB meningitis

Papilloedema?
Tumour
Malignant hypertension
Benign intracranial hypertension
Any CNS infection, if prolonged (eg >2wks)eg TB meningitis
Others
Temporal arteritis (ESR elevated)
Glaucoma
Paget's disease (Alk Phos elevated)
Sinusitis
Altitude sickness
Cervical spondylosis
Venous sinus occlusion (focal neurological deficits)
Vertebral artery dissection (neck pain and cerebellar/medullary signs)

Worrying features or red flags
First and worst headache subarachnoid haemorrhage
Thunderclap headache subarachnoid haemorrhage; .
Unilateral headache and eye pain—cluster headache, acute glaucoma
Unilateral headache and ipsilateral symptoms migraine, tumour, vascular
Cough-initiated headache raised ICP/venous thrombosis
Persisting headache ± scalp tenderness in over 50 temporal arteritis
Headache with fever or neck stiffness meningitis
Change in the pattern of "usual headaches"
Decreased level of consciousness