Acute Headache

Overview

This StatPearls review by Baraness and Baker, last updated in July 2023, covers the assessment and management of headache in the emergency department. Headache makes up about 3% of emergency department visits, and 96% are benign, but some are life-threatening, so the main task is to identify patients at risk of serious underlying disease. The International Classification of Headache Disorders divides headaches into primary (tension-type, migraine and cluster), secondary, and cranial neuropathies.

History and examination

History and examination often settle the diagnosis. Low-risk features include age under 50, typical primary headache features, a similar past headache, a normal neurological examination and no change in pattern. Red flags are summarised by SNOOP: systemic illness, neurological signs, new or sudden onset (especially after 50), other features such as trauma, exertion or waking from sleep, and a change from a previous headache pattern. Serious causes to consider include subarachnoid haemorrhage (thunderclap headache), cervical artery dissection, meningitis and encephalitis, cerebral venous sinus thrombosis, stroke, carbon monoxide poisoning, acute angle-closure glaucoma, idiopathic intracranial hypertension, hypertensive emergency and giant cell arteritis.

Investigations

Routine laboratory tests rarely help, though glucose, a pregnancy test, carboxyhaemoglobin, ESR and CRP are used when specific causes are suspected. Neuroimaging is advised for new neurological deficits, sudden severe headache, a new headache after 50 or in HIV-positive patients, and the yield rises with features such as recent head trauma, altered mental status or papilloedema. Non-contrast head CT is the screening test, and in patients who arrive within 6 hours of onset CT alone is sufficient to rule out subarachnoid haemorrhage. Lumbar puncture is considered for suspected meningitis, intracranial pressure disorders or a negative CT with high suspicion, but it should not precede CT when raised pressure is suspected and should not delay antibiotics.

Treatment

Treatment of primary headache aims at fast, lasting analgesia with few side effects, using parenteral drugs when nausea is present: antidopaminergic agents (prochlorperazine, metoclopramide), acetaminophen, NSAIDs, triptans (best by non-oral routes) and dexamethasone to reduce recurrence in prolonged migraine. Cluster headache responds to high-flow oxygen. Opiates should be avoided, and a sphenopalatine ganglion nerve block is a newer option. Secondary headaches are treated by addressing the underlying cause.

Prognosis

Primary headaches do not cause death or permanent disability but often recur, and medication overuse (rebound) headache is a risk of frequent analgesic use. Patients should be advised about triggers, follow-up and when to return.