Thunderclap Headache & SAH
Objective: Treat sudden-onset worst headache as possible subarachnoid hemorrhage: protect the clock, check glucose, and do not downgrade it because the neuro exam is “normal.”
Why This Is Hard
They are 42, photophobic, and “get migraines.” Crews give ondansetron and dim the lights. AHA/ASA aneurysmal SAH teaching: thunderclap headache — sudden, maximal within seconds to a minute — is the classic warning. A normal GCS does not clear an aneurysm. Sentinel leaks get sent home and then rebleed. Your job is suspicion and the right door, not a diagnosis.
- Onset story is the exam: seconds vs hours, worst of life, exertion/sex/Valsalva, neck stiffness, vomiting, seizure at onset, photophobia.
- Glucose. Focal deficit or seizure still runs a stroke pathway. See stroke-mimics.
- Keep them still, head of bed up if protocol, no wrestling for an IV in a screaming photophobic patient if you already have access.
Street Sequence
- ABCs. Glucose. Quick neuro: pupils, speech, arms, neck.
- If thunderclap / worst of life / meningismus / new deficit: short scene, CT-capable hospital (stroke/neurosurgery capable if your system triages that way).
- Treat pain and nausea per protocol without delaying exit. This is not a 25-minute migraine workup.
- If they seize or drop GCS: airway, destination even more urgent.
Field Rules (Education)
- Thunderclap means peak intensity in seconds, not a headache that built all afternoon.
- Normal neuro exam does not clear SAH. Sentinel headache can look “just migraine.”
- Neck stiffness plus fever also puts meningitis on the table — still an ED, still not home. See the meningitis lesson.
- You are not the CT: under-calling a sentinel bleed sends them home. Over-calling possible SAH is the cheaper error.
- Thunderclap / worst of life — not treating as simple migraine
- Glucose is __
- CT-capable destination
- Scene time short
Field Pitfalls
- Migraine cocktail and a refusal because GCS is 15.
- A 20-minute scene lights-down “to help the photophobia.”
- Skipping glucose on a “obvious migraine.”
Practice
60-second drill
42-year-old, pain 10/10 in seconds while lifting, neck stiff, GCS 15, wants to stay dark. Radio sentence and destination. What finding is not required to take them?
Related: Stroke Recognition & Last Known Well, Meningitis & Fever With Stiff Neck.
Sources & Further Study
Named guidelines for further study. They are not clinical orders and do not replace your protocol or medical direction.
- NASEMSO National Model EMS Clinical Guidelines (2022) — U.S. EMS model language; protocol still wins
- 2023 AHA/ASA Aneurysmal Subarachnoid Hemorrhage Guideline — sudden severe headache is the classic presentation — urgent CT-capable evaluation
- 2026 AHA/ASA Acute Ischemic Stroke Guideline — EMS: glucose, short scene, right stroke hospital — severe headache with deficit still activates
Education only. Apply learning within your protocols and medical direction. This is not clinical care guidance.
Check Your Understanding
Street decisions from this lesson only. After you check, the key is highlighted. Education practice — not a certification exam.