Q. I have heard that one symptom of a stroke is “the worst headache you can imagine.” I recently had a migraine that was so much more painful than previous ones that I worried it was a stroke. Is there any way to tell a migraine from a “stroke headache”?
A. The term “stroke” covers several distinct events that differ in location and cause. Some types of stroke can trigger a headache; others usually don’t. To understand the connection, it’s helpful to know a bit about the brain and pain. Brain tissue, and the blood vessels embedded in it, doesn’t register pain. But the membranes that surround the brain and the blood vessels that run through them do register pain.
The most common kind of stroke — ischemic stroke — occurs when a blood clot blocks an artery in the brain. These don’t usually bring on a headache. A hemorrhagic stroke stems from bleeding in the brain. Because bleeding stretches the outer membranes, headache, sometimes a very intense headache, commonly accompanies a hemorrhagic stroke.
A subarachnoid hemorrhage is one type of bleeding stroke. It is generally caused by the rupture of a weakened bulge (an aneurysm) in a blood vessel at the base of the brain. The bleeding triggers a very intense headache, the kind often referred to as “the worst headache you can imagine.”
The severity of a headache is a difficult thing to gauge. A better way to tell the difference between a severe headache or migraine and a “stroke headache” is how the pain develops. A migraine usually starts small and takes a while to reach its peak. The headache that accompanies a subarachnoid hemorrhage comes on in seconds, about as fast as a blow to the head. It may render a person momentarily unconscious, something that doesn’t happen with migraine.
When it comes to recognizing a stroke, sudden onset of headache is a more important guide than intensity. If a headache appears out of the blue and reaches peak severity in seconds, call 911 for an ambulance to bring you to the nearest emergency room.
— Egilius L.H. Spierings, M.D., Ph.D.
Associate Clinical Professor of Neurology
Harvard Medical School
Brigham and Women’s Hospital