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Neurology

Subarachnoid Hemorrhage

Bleeding into the subarachnoid space, most commonly from a ruptured saccular berry aneurysm; presents as sudden 'worst-ever' thunderclap headache with high early mortality.

Last reviewed 14 Jul 2026 - MedicoMedics editorial team

Aneurysmal subarachnoid haemorrhage

Pathophysiology

80% from saccular aneurysms at anterior circle of Willis; risk: hypertension, smoking, ADPKD, connective-tissue disease.

Sources: AHA/ASA SAH (Stroke 2023;54:e314); ISAT (Lancet 2002;360:1267)

Presentation

Sudden 'worst headache of life', nausea/vomiting, meningismus, transient LOC, focal deficits or seizure; sentinel bleed may precede rupture.

Diagnosis

Non-contrast CT within 6 h >98% sensitive. LP for xanthochromia if CT negative. CTA/DSA localises aneurysm.

Management

BP <160 SBP with nicardipine; secure aneurysm within 24-72 h (coiling preferred over clipping). Nimodipine 60 mg PO q4h x 21 days reduces delayed ischaemia. EVD for hydrocephalus.

Sample USMLE-style MCQs

Try 5 questions on this topic. Practice hundreds more free with a trial.

Question 1

45-year-old thunderclap headache and neck stiffness. CT normal 8 h later. Next?

Question 2

Prophylaxis reducing delayed cerebral ischaemia?

Question 3

Best-known trial supporting coiling over clipping?

Question 4

Strong risk factor for SAH?

Question 5

Day-6 post-SAH new hemiparesis and confusion. Diagnosis?

References

Primary guidelines and peer-reviewed sources used for this entry. Reviewed 14 Jul 2026 by MedicoMedics editorial team.

  1. AHA/ASA SAH (Stroke 2023;54:e314)
  2. ISAT (Lancet 2002;360:1267)

Frequently asked

Role of nimodipine?

Reduces delayed cerebral ischaemia from vasospasm.

First imaging?

Non-contrast head CT.

Preferred aneurysm treatment?

Endovascular coiling (ISAT).

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