Emergency Department Evaluation of Headache

Initial Assessment: Red Flags for Secondary Headache

The American Heart Association recommends identifying features that suggest dangerous secondary causes requiring immediate investigation, such as "worst headache of my life", which is present in 80% of subarachnoid hemorrhage (SAH) cases 1, 2
Sudden onset ("thunderclap") headaches, particularly during physical exertion or sexual activity, are red flags for secondary headache 1, 2
Sentinel/warning headaches occur in 20% of patients 2-8 weeks before major SAH rupture 1, 2
New headaches in older patients (>50 years) have a higher risk of secondary causes 3
Progressive worsening pattern over days to weeks is a red flag for secondary headache 4
Headaches that awaken patients from sleep are a red flag for secondary headache 4
Headaches worsened by Valsalva maneuver are a red flag for secondary headache 4

Non-contrast head CT is the cornerstone diagnostic test and must be obtained when red flags are present, with a sensitivity for SAH of 98-100% within the first 12 hours 1, 2
If CT is negative but clinical suspicion remains high, lumbar puncture is mandatory to detect xanthochromia and rule out SAH 1, 2
The most common diagnostic error is failure to obtain CT scan, associated with 4-fold higher mortality/disability 1, 2

The American Academy of Family Physicians recommends characterizing the primary headache disorder by assessing location, duration, character, intensity, and associated symptoms 4, 5
Medication overuse headache occurs with frequent use of acute treatments, and critical to identify, with a frequency threshold of more than 2 times per week increasing risk 4, 6
High-risk medications for medication overuse headache include ergotamine, opiates, triptans, and butalbital-containing compounds 6

Discharge instructions must include a rescue medication plan for home use when treatments fail, education on medication overuse prevention, and scheduled follow-up within 2-3 months 4, 6, 3
The American College of Physicians recommends avoiding opioids for migraine treatment due to poor effectiveness and risk of medication overuse headache and dependency 4