Acute Headache, SAH & Intracranial Crises
Evidence-based emergency approach to acute catastrophic headaches and intracranial crises. Details the Ottawa SAH rule, non-contrast head CT sensitivity within 6 hours, lumbar puncture xanthochromia analysis, cerebral venous sinus thrombosis (CVST), and spontaneous intracranial hypotension.
Resuscitation Quick Ribbon (First 2 Minutes)
Bottom-Line Clinical Pearl
A high-quality non-contrast head CT performed within 6 hours of headache onset and read by an attending radiologist has a sensitivity of 99.9% for subarachnoid hemorrhage, virtually eliminating the need for routine lumbar puncture in this specific window.
A thunderclap headache (abrupt onset reaching maximal intensity in < 1 minute, often described as 'worst headache of life') is an emergency until non-aneurysmal and aneurysmal causes are ruled out:
| Etiology | Clinical Presentation & Triggers | First-Line Diagnostic Strategy | Emergency Management |
|---|---|---|---|
| Aneurysmal SAH (85% of non-traumatic SAH) | Thunderclap onset, neck stiffness, photophobia, syncope, transient loss of consciousness | Non-contrast Head CT; if negative > 6h, LP or CTA | Target SBP < 140 mmHg, Nimodipine 60 mg q4h, early neurosurgery/interventional coiling |
| Cerebral Venous Sinus Thrombosis (CVST) | Progressive severe headache, visual changes, papilledema, hypercoagulable state/OCP/pregnancy | CT Venogram (CTV) or MR Venogram (MRV) with contrast | Therapeutic anticoagulation (unfractionated heparin or LMWH) even in the presence of venous hemorrhagic infarction |
| Reversible Cerebral Vasoconstriction Syndrome (RCVS) | Recurrent thunderclap headaches over days/weeks, postpartum or vasoactive drugs (SSRI, triptans, decongestants) | CT Angiography / MR Angiography showing 'string of beads' arterial narrowing | Discontinue offending agent; nimodipine or verapamil; avoid triptans and ergots |
| Cervical Artery Dissection (Carotid/Vertebral) | Neck pain, unilateral occipital/frontal headache, Horner syndrome (ptosis + miosis), transient ischemic attack | CTA of the Neck and Head (cervical soft tissue window) | Antiplatelet therapy or therapeutic anticoagulation; vascular surgery/neurointerventional consult |
| Pituitary Apoplexy | Thunderclap headache, bitemporal hemianopsia, ophthalmoplegia, sudden hypotension | MRI Brain (or fine-cut pituitary CT); stat endocrine labs (cortisol) | Immediate Stress-dose Hydrocortisone (100 mg IV); emergent neurosurgery consult for transsphenoidal decompression |
The Ottawa SAH Rule is applied to alert, neurologically intact patients >= 15 years old with a new, acute, severe non-traumatic headache peaking within 1 hour. It carries 100% sensitivity for SAH. Investigate for SAH if ONE or more features are present:
- Age >= 40 years
- Neck pain or stiffness on exam
- Witnessed loss of consciousness
- Onset during physical exertion (coitus, weightlifting, Valsalva)
- Thunderclap headache (instant peak pain)
- Limited neck flexion on examination
Diagnostic algorithm based on time from headache onset:
| Time from Onset | Diagnostic Modality | Sensitivity & Interpretation | Next Clinical Action |
|---|---|---|---|
| < 6 Hours | Non-contrast Head CT (modern 3rd generation >= 16-slice scanner) | Sensitivity > 99.9% when interpreted by qualified radiologist | If CT is negative and patient is neurologically intact, SAH is ruled out. LP can be withheld after shared decision-making. |
| > 6 Hours | Non-contrast Head CT followed by Lumbar Puncture (or CTA Head) | CT sensitivity decreases over time (85% at 5 days, 50% at 1 week) | Perform LP: analyze Tube 1 and Tube 4 RBC count and examine for xanthochromia via spectrophotometry or visual inspection. |
| Traumatic Tap vs True SAH | Tube 1 to Tube 4 RBC count comparison | True SAH: RBC count remains elevated without significant clearing (> 25% drop) between Tube 1 and 4; xanthochromia present >= 12h post-bleed | If Tube 4 RBC count is clearing and xanthochromia is negative, traumatic tap is likely. |
- Blood Pressure Control: Target SBP < 140 mmHg (or MAP < 110 mmHg) to reduce rebleeding risk prior to aneurysm securement. First-line agent: Nicardipine IV infusion (5-15 mg/hr) or Labetalol IV boluses.
- Vasospasm Prevention: Nimodipine 60 mg orally (or via NG tube) every 4 hours. Do not give IV (causes fatal hypotension). If hypotension occurs, decrease to 30 mg every 2 hours.
- Seizure Prophylaxis: Levetiracetam 1000 mg IV load (or 20 mg/kg) to prevent non-convulsive seizures and intracranial pressure spikes.
- Anticoagulation Reversal: If on warfarin -> 4-Factor PCC (25-50 units/kg) + Vitamin K 10 mg IV. If on DOAC -> Andexanet alfa (apixaban/rivaroxaban) or Idarucizumab (dabigatran).
- ICP Management: Elevate head of bed 30 degrees; mild sedation/analgesia with fentanyl; for acute hydrocephalus, place emergency external ventricular drain (EVD).
- Immediate Neurosurgical & Neurocritical Care Consult: All confirmed or highly suspected SAH patients require immediate transfer to a comprehensive stroke / tertiary neurovascular center.
- Aneurysm Repair: Early endovascular coiling or surgical clipping is performed within 24-48 hours to prevent rebleeding (rebleeding mortality exceeds 50-70%).
- Document Onset Time Precisely: Documenting the exact time pain reached maximal intensity is legally and clinically paramount for determining whether the 6-hour CT rule applies.
Test Your Acute Headache, SAH & Intracranial Crises Clinical Acumen
Directly launch an active-recall practice block from our 8,400+ validated COMLEX Level 1, 2-CE & 3 board question bank with complete explanations.
Related Emergency Protocols & Differentials
Acute Ischemic And Hemorrhagic Stroke
Clinical emergency medicine protocol and decision pathway.
Open Protocol Related EM ProtocolHead Trauma And Intracranial Hypertension
Clinical emergency medicine protocol and decision pathway.
Open Protocol Related EM ProtocolAltered Mental Status And Coma
Clinical emergency medicine protocol and decision pathway.
Open Protocol