Subarachnoid hemorrhage is caused by what?

• A. Rupture of a blood vessel or intracranial aneurysm, typically at Circle of Willis or major cranial artery branches and commonly after head trauma
• B. Blockage due to dehydration
• C. Bacterial infection
• D. Vitamin deficiency

Answer: (A)

Subarachnoid hemorrhage happens when a blood vessel in the brain ruptures and bleeds into the subarachnoid space. The most common cause is rupture of an intracranial aneurysm, typically at the Circle of Willis or major cerebral artery branches. This sudden bleed irritates the meninges and raises intracranial pressure, producing a sudden, severe headache often described as the worst headache of life, along with possible neck stiffness, photophobia, or loss of consciousness. Other options don’t explain bleeding into the subarachnoid space: dehydration isn’t a typical cause of arterial rupture, bacterial infection leads to meningitis rather than hemorrhage, and vitamin deficiency doesn’t produce this pattern of intracranial bleeding.