In Part 1 of this episode on Headache Pearls & Pitfalls – Migraine Headache & Subarachnoid Hemorrhage, Dr. Anil Chopra and Dr. Stella Yiu discuss the best evidenced-based management of migraine headache in the ED including the use of dexamethasone, dopamine antagonists, the problems with narcotics and the efficacy of ‘triptans’. An easy way to remember the worrisome symptoms of headache indicating a serious cause is reviewed followed by a detailed discussion of the pearls, pitfalls and controversies around the work-up of Subarachnoid Hemorrhage (SAH) in light of some exciting recent literature, including the basis for a new Canadian decision rule for SAH.

They answer questions like: With the ever improving resolution of CT, should we still be doing LP after negative plain CT head for all our thunderclap headache patients? What is the role for CT angiogram and MRI in the workup of acute headache in the ED? What evidenced-based treatments can we initiate in the ED for our SAH patients that will improve outcomes? and many many more…..

Written Summary and blog post by Lucas Chartier, edited by Anton Helman May 2011

Cite this podcast as: Chopra, A, Yiu, S, Helman, A. Part 1: Migraine Headache and Subarachnoid Hemorrhage. Emergency Medicine Cases. May, 2011. Accessed [date].


POUND mnemonic for diagnosis of migraine: Pulsatile quality, 4‐72 hOurs, Unilateral pain, Nausea, and Disabling intensity – 4 out of 5 features present gives a positive likelihood ratio of 24 for this headache to be a migraine (in a study based out of GP clinics); photophobia and phonophobia are also often present

  • Retinal and vitreous detachment produce flashes or floaters that are unilateral, white in color and produce a “curtain descending on the vision” phenomenon, as opposed to the migraine‐associated bilateral, coloured and tunnel‐vision symptoms

SSNOOP mnemonic for red flags: Systemic signs (fever, weight loss), Secondary risk factors (immuno‐ compromised status, HIV), Neurological signs (speech deficit, cranial nerve abnormalities), Onset – abrupt, Older age (>40yo), Progression of symptoms

  • To make the diagnosis of migraine, the patient really should have had prior repeated and similar symptoms that have been diagnosed as a migraine by a physician, not simply self‐diagnosis

Emergency Department Treatment Migraine Headache

  • Dopamine antagonist such as metoclopraminde (Maxeran©) or prochlorperazine (Stemetil©) in a mini‐bag infusion over 15min (not as an injection), alongside an anticholinergic such as benzatropine (Benztropine©) or diphenhydramine (Benadryl©) to decrease the extra‐pyramidal symptom of akathisia (i.e. restlessness) – NNT of 5 for these two adjuncts
    • Remember that the mere improvement of the headache with therapy does NOT exclude serious pathology
  • Steroids (eg, dexamethasone 10‐15mg IV or PO) at discharge may be useful to prevent rebound headache within 72hrs by decreasing the inflammation of the blood vessels in the brain
  • At discharge, naproxen 500mg PO has been shown to be as useful as the ‘triptan’ class of drugs, which should only be prescribed in people who have had response to them in the past and who do not have hypertension or cardiovascular disease

Update 2017:  A randomized, double-blind control study of 127 patients demonstrated quick and sustained relief of moderate to severe migraines in 60% of those receiving IV prochlorperazine and diphenhydramine vs 31% receiving IV hydromorphone, with a NNT of 4Abstract

emcases-updateUpdate 2020: IV fluids are frequently used in the ED as part of the treatment for benign headaches. A randomized, single-blinded clinical trial demonstrated no statistically or clinically significant effect of IV fluids on headache pain, or on secondary outcomes including nausea, use of rescue medications, admissions, or headache resolution. Abstract


Update 2022: A systematic review found that the use of an anticholinergic agent diphenhydramine following ED treatment of primary headache with neuroleptics or metoclopramide did not reduce the incidence of akathisia compared to placebo (RR 0.83, 95% CI 0.43-1.61). Note – these findings relied on the results of two small randomized controlled trials with incomplete outcome reporting. Abstract


SUM mnemonic for diagnosis of SAH: Sudden onset, Unlike previous headaches, Maximal at onset

  • Also consider risk factors of family history of cerebral aneurysm, SAH or polycystic kidney disease, or collagen vascular diseases, hypertension, and binge drinking, smoking or use of cocaine, as well as an elicited history of a recent similar headache (i.e. sentinel bleed), onset during exertion or pre‐  syncope or syncope associated with this headache
  • Migraine itself is not a risk factor for SAH, but remember that migraine‐sufferers may have SAH as well!
  • ECG changes in 50‐100% of patients due to neurogenic myocardial stunning and coronary vasospasm: deep, wide precordial T‐wave inversion, bradycardia, and prolonged QT – beware of anticoagulating these patients on the assumption of acute coronary syndrome

Study by Perry et al. of signs of SAH:

  • The following are strongly and reliably associated with SAH: age >40, neck stiffness or pain, onset of headache on exertion, vomiting, witnessed loss of consciousness, and elevated BP >160/100

Also consider the following signs: stroke‐like symptoms, seizure or 3rd cranial nerve palsy from mass effect, 6th cranial nerve palsy with diplopia, or subhyloid hemorrhage (i.e. dense red on fundoscopy, also called Terson syndrome – patient will eventually need referral to ophthalmology), and even meningismus


Update 2016: Meta-analysis evaluates the diagnostic accuracy of history, physical exam, CT and LP for SAH. Abstract

emcases-update Update 2013: Ottawa Subarachnoid Hemorrhage Rule – Clinical Decision Rules to Rule Out Subarachnoid Hemorrhage for Acute Headache Full pdf

emcases-updateUpdate 2014: External validation of the Ottawa subarachnoid hemorrhage clinical decision rule in patients with acute headache Abstract

Workup of Subarachnoid Hemorrhage

  • CT scan of the head – sensitivity of at least 95% in first 12hrs after onset , but decreases to 85% the next day and 50% after one week
  • Lumbar puncture (LP) is therefore still standard of care, despite 25% risks of post‐LP headache, and the small risks of neurological damage and infection
  • Do NOT wait to 12hrs after onset (when xantochromia becomes reliably present) to perform LP as patients with the disease would therefore be put at risk of a subsequent fatal bleed
  • A true SAH‐positive tap may hide in a ‘traumatic tap’, so call a tap a ‘negative tap’ if and only
  • Opening pressures should ALWAYS be done and documented, because it might be elevated in SAH (will never be elevated in traumatic tap), and may help diagnose alternate conditions, such as idiopathic intracranial hypertension or cerebral venous thrombosis
  • Post‐LP headaches classically occur 3 days later, are worse when not supine, and are a result of CSF leak from the dura – they are minimized by using smaller (i.e. 25G – tip: use a 16G needle as a trocar to penetrate the soft tissues, then insert the 25G needle inside this), atraumatic (non‐cutting) blunt tip needles; bedrest, caffeine and hydration have all been shown to NOT be effective at reducing post‐LP headaches, and the definitive treatment involves an autologous blood patch inserted by an anesthetist
  • If a patient refuses an LP or the physician fails to obtain CSF fluid, consider doing a CT‐angiogram – this will exclude aneurysms that could lead to bad outcomes in the short term, but may also lead to false positive: 2‐6% of the population has cerebral aneurysms, but CT‐A cannot identify whether this particular aneurysm is the culprit for the headache, or even if it has a high likelihood of rupturing in the future

emcases-updateUpdate 2016:Meta-analysis of more than 8000 patients shows only 0.1-0.2% miss rate if CT done within 6hrs of headache onset. Abstract


emcases-updateUpdate 2017:A recent prospective study focused on differentiating SAH and a traumatic tap, has found that if you have a patient you are concerned may have a SAH and the following are true: negative CT head, no xanthochromia, and a LP that has less than 2000 x 10^6 cells/L, you may not need additional testing. Abstract

emcases-updateUpdate 2022: A retrospective analysis of 347 patients with a subarachnoid hemorrhage found that the sensitivity of modern MSCT was 99.6% for aneurysmal SAH and 99% for all SAH at 48 hours after headache onset, and 100% for aneurysmal SAH at 24 hours after headache onset. There were no differences observed between 128-slice and 64-slice CT scanners. Abstract

Emergency Department treatment of Subarachnoid Hemorrhage

  • To prevent re‐bleeding, treat hypertension only if the mean arterial pressure is persistently over 100‐110 for a few hours, and consider involving your consultant neurosurgeon on the target and method to do this – labetalol 20mg IV bolus followed by an infusion may be appropriate
  • To prevent vasospasm and resultant cerebral infarct, nimodipine (calcium‐channel blocker) 60mg PO/NG q4‐6hrs needs to be started within 24hrs of presentation
  • To prevent seizures, which will occur in 5‐20% of patients with SAH, consider starting anti‐epileptics


Update 2021: A multi-center prospective, randomized, controlled study involving 955 patients with CT-proven aneurysmal SAH demonstrated that early and short-term TXA immediately after diagnosis has no impact on clinical outcome at 6 months, including risk of re-bleeding. Abstract

For more on headaches in the emergency department on EM Cases:
Episode 14 Part 2: Thunderclap Headache – Cerebral Venous Thrombosis and Cervical Artery Dissection
Best Case Ever 3: Emergency Headache – Importance of Opening Pressure

Dr. Chopra, Dr. Yue and Dr. Helman have no conflicts of interest to declare.

Key References

Perry JJ, Stiell IG, Sivilotti MLA, et al. High risk clinical characteristics for subarachnoid haemorrhage in patients with acute headache: prospective cohort study. BMJ 2010;341:c5204

Tintinalli J, Stapczynski J, Ma OJ et al. Tintinalli’s Emergency Medicine: A Comprehensive Study Guide, Seventh Edition (Book and DVD). Mcgraw-hill; 2010.

Hockberger RS, Walls RM. Rosen’s Emergency Medicine – Concepts and Clinical Practice, 2-Volume Set,Expert Consult Premium Edition – Enhanced Online Features and Print,7, Rosen’s Emergency Medicine – Concepts and Clinical Practice, 2-Volume Set. Elsevier Health Sciences; 2009.

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