What is a bleeding (hemorrhagic) stroke?
Hemorrhagic stroke is caused by bleeding in the brain from a burst or leaking blood vessel. Of the two major types of stroke, bleeding stroke is the more rare: only 1 in 10 strokes are bleeding strokes, and the remaining 90% are blocked-vessel (ischemic) strokes. Bleeding strokes are the most dangerous kind of stroke: about 37% of people who have a bleeding stroke die within 30 days, compared with 8% to 12% of people with a blocked-vessel stroke.
The most common causes of bleeding in the brain are high blood pressure, a ruptured aneurysm, or in-born malformations of the blood vessels (arteriovenous malformation, or AVM).
What are the different types of bleeding stroke?
There are two main types of bleeding stroke, divided by whether the bleeding is in the brain itself or in the space between the surface of the brain and the skull.
Intracerebral hemorrhage is bleeding within the brain. The most common cause of intracerebral hemorrhage is high blood pressure, which can stress the walls of the delicate blood vessels in the brain and cause them to burst, leaking blood into surrounding brain tissue.
Subarachnoid hemorrhage is bleeding in the tissue or space surrounding the brain. The most common cause of subarachnoid hemorrhage is an aneurysm – a thin or weak spot in a blood vessel that balloons out and can burst. This cause of bleeding stroke is more common in women than in men. Less often, bleeding from a burst abnormal tangling of veins and arteries (AVM) in the brain can cause a subarachnoid hemorrhage.
Illustration depicting a brain aneurysm. An aneurysm can burst and cause a bleeding stroke.