Which condition is most likely when a patient reports the worst headache of life localized to one side or back of the head?

• A. Tension headache
• B. Subarachnoid hemorrhage
• C. Cluster headache
• D. Middle cerebral artery occlusion

Answer: (B)

A thunderclap headache—the sudden, explosive onset of pain that’s described as the worst headache of life—points to a subarachnoid hemorrhage from a ruptured aneurysm. This type of bleed irritates the meninges and causes a rapid, severe headache that can be localized to one side or the back of the head, often with neck stiffness, photophobia, nausea, or brief loss of consciousness. That urgent, life-threatening red flag is what sets SAH apart from other headaches.

Tension headaches tend to be gradual, bilateral, and not life-threatening. Cluster headaches are extremely painful but come in short, repetitive bursts with autonomic symptoms around the eye and don’t usually present as the single worst headache of life. A middle cerebral artery occlusion (ischemic stroke) can cause focal neurological deficits (like weakness or speech changes) and headache, but the hallmark is new focal signs rather than a sudden thunderclap of pain.