A 55-year-old man presents with sudden-onset severe headache described as the 'worst headache of his life.' Non-contrast CT head shows hyperdensity filling the basal cisterns and sulci of the sylvian fissures symmetrically. Which diagnosis should be urgently confirmed?
- A Bacterial meningitis
- B Hypertensive encephalopathy
- C Subarachnoid hemorrhage ✓
- D Viral encephalitis
Correct answer: C. Subarachnoid hemorrhage
Explanation
Subarachnoid hemorrhage (SAH) classically presents with sudden thunderclap headache and non-contrast CT within 6 hours of onset shows hyperdense blood filling the basal cisterns, sylvian fissures, and cortical sulci. CT sensitivity for SAH approaches 98% within 6 hours of onset. The most common cause is rupture of a saccular intracranial aneurysm, typically at the circle of Willis. Bacterial meningitis may show subtle sulcal effacement but not frank cistern hyperdensity. Viral encephalitis shows T2/FLAIR signal change in limbic structures on MRI.
Reference: Grainger & Allison's Diagnostic Radiology, 7th ed.
High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP
Written and medically reviewed by the StethoPrep medical team.