What is hemorrhagic stroke?
Hemorrhagic stroke accounts for 10 percent to 15 percent of all cases of stroke. In hemorrhagic stroke, bleeding in the brain itself (intracerebral hemorrhage) or between the brain and the skull (subarachnoid hemorrhage) disrupts brain function. Bleeding usually occurs because of a rupture in arterial walls that are already weakened by high blood pressure. A pool of
blood compresses brain tissue in its vicinity, preventing adequate amounts of fresh blood from reaching the area.
Hemorrhage (or bleeding) from an artery in the brain can be caused by a head injury or a burst aneurysm. Aneurysms are blood-filled pouches that balloon out from weak spots in the artery wall. They're often caused or made worse by high blood pressure. Aneurysms aren't always dangerous, but if one bursts in the brain, they cause a hemorrhagic stroke.
When a cerebral or subarachnoid hemorrhage occurs, the loss of a constant blood supply means some brain cells no longer can work. Accumulated blood from the burst artery also may put pressure on surrounding brain tissue and interfere with how the brain works. Severe or mild symptoms can result, depending on the amount of pressure.
The amount of bleeding determines the severity of cerebral hemorrhages. In many cases, people with cerebral hemorrhages die of increased pressure on their brains. But those who live tend to recover much more than people who've had strokes caused by a clot. That's because when a blood vessel is blocked, part of the brain dies — and the brain doesn't regenerate. But when a blood vessel in the brain bursts, pressure from the blood compresses part of the brain. If the person survives, gradually the pressure goes away. Then the brain may regain some of its former function.
High blood pressure is the main cause. Atherosclerosis (the buildup of fatty plaque in the arteries) weakens arterial walls, further increasing the risk of hemorrhage due to hypertension. Bleeding disorders (such as hemophilia and leukemia) and the use of anticoagulant or thrombolytic drugs increase the risk of intracerebral bleeding. Aneurysms (weak spots in the wall of an artery that may burst) are a major cause of subarachnoid hemorrhage. They are often due to congenital defects (defects present at birth). Blood vessel abnormalities such as arteriovenous malformation (AVM) may result in a stroke. A head injury may rupture arteries in the brain. Brain tumors may lead to intracerebral bleeding. |
