The Difference Between Strokes and Aneurysms

There are two main types of strokes:

• Ischemic strokes are caused when blood vessels to the brain are blocked. They account for 87% of all strokes.
• The other 13% of strokes are hemorrhagic, caused by leakage of blood into or around the brain tissue.

Hemorrhagic strokes can be caused by a ruptured cerebral (brain) aneurysm. Commonly confused with stroke, cerebral aneurysms are "blisters" that form when a weak spot in a blood vessel of the brain bulges or balloons out. If an aneurysm ruptures, it causes a stroke, but not all strokes are caused by aneurysms.

Types of Hemorrhagic Strokes

Hemorrhagic strokes can be subarachnoid or intracerebral.

Subarachnoid hemorrhages:

• Are less common than intracerebral hemorrhages
• Cause bleeding in the space around the brain and blood vessels

About one third of people who have a subarachnoid hemorrhage will have a good outcome. Another third will have a disability, and the remaining third will die immediately.

Intracerebral hemorrhages:

• Are more common than subarachnoid hemorrhages
• Cause bleeding into the brain tissue

"Hemorrhagic strokes are by far the most fatal," says Northwestern Medicine Neurosurgeon Babak S. Jahromi, MD, PhD. "While aneurysm rupture is rare, once an aneurysm bursts, the odds of brain damage and death drastically increase. Fortunately, there are advanced treatment options for stopping unruptured aneurysms in their tracks."

Let's take a closer look at brain aneurysms.