Neurology Neurology · Emergency · High Yield

Headache Causes

Headache is one of the most common presenting complaints. A systematic approach separates the rare dangerous causes from the common benign ones.

✦ The Mnemonic

"SNOOP4 — Red Flag Headache Features"

Systemic illness · Neurological signs · Onset sudden · Older age · Postural · Papilloedema · Progressive · Pregnancy

SAH Subarachnoid haemorrhage Thunderclap — worst-ever headache, maximal at onset; CT then LP for xanthochromia if CT negative

Mi Migraine Most common severe recurrent headache; throbbing; unilateral; nausea; photophobia; aura in 30%

TTH Tension-type headache Most common headache overall; bilateral; band-like pressure; no nausea; no aura

CH Cluster headache Severe unilateral orbital pain; 15–180 min; autonomic features (lacrimation, ptosis, rhinorrhoea); men; circadian

IIH Idiopathic intracranial hypertension Young obese women; daily headache; pulsatile tinnitus; papilloedema; visual field loss

Tri Trigeminal neuralgia Brief electric shock pain in trigeminal distribution; trigger points; V2/V3 most common; carbamazepine first-line

GCA Giant cell arteritis Age >50; temporal artery tenderness; jaw claudication; raised ESR/CRP; treat with prednisolone IMMEDIATELY to prevent blindness

📚 Clinical Breakdown

Thunderclap headache: maximal at onset, reaching peak within 1 second to 1 minute. SAH is the most dangerous cause. Investigations: CT head (90% sensitive at 6 hours); if CT negative — LP at 12 hours for xanthochromia (bilirubin breakdown product persists for 2 weeks). Never discharge without adequate investigation.

Giant cell arteritis (GCA): temporal artery biopsy is the gold standard, but treatment must NOT be delayed for biopsy — start prednisolone 40–60 mg/day immediately if GCA suspected with visual symptoms. Risk of sudden permanent blindness from anterior ischaemic optic neuropathy. Biopsy remains positive for 2–4 weeks after starting steroids.

Cluster headache: attacks occur in clusters (weeks to months) then remission. Pain is the most severe pain known — 'suicide headache'. Acute treatment: high-flow 100% oxygen (most effective), sumatriptan SC/nasal. Prevention: verapamil (first-line), lithium, prednisolone short course. Melatonin for circadian component.

Thunderclap headache SAH until proven otherwise — CT then LP

GCA — act immediately Start prednisolone before biopsy

Cluster headache acute Rx 100% O2 + sumatriptan SC

Trigeminal neuralgia first-line Carbamazepine

⭐ Clinical Pearl

Medication overuse headache (MOH): daily or near-daily headache caused by taking acute headache medication on >10–15 days/month for >3 months. Affects all analgesics including triptans. Treatment: complete withdrawal of overused medication (rebound worsening for 2–4 weeks), then preventive therapy. Explain this to every patient prescribed regular analgesics for headache.