Hemorrhagic stroke

Injury	Disease	Nutrition	Poison

Symptoms	Surgery	Test	Special Topic

Stroke

Central nervous system

Hemorrhagic stroke

Definition:

Hemorrhagic stroke involves bleeding within the brain, damaging nearby brain tissue.

Alternative Names:
Brain bleeding; Brain hemorrhage; Stroke - hemorrhagic
Causes, incidence, and risk factors:

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Hemorrhagic stroke occurs when a blood vessel bursts inside the brain. The brain is very sensitive to bleeding and damage can occur very rapidly, either because of the presence of the blood itself, or because the fluid increases pressure on the brain and harms it by pressing it against the skull.

Bleeding irritates the brain tissue, causing swelling. The surrounding tissues of the brain resist the expansion of the bleeding, which is finally contained by forming a mass (hematoma). Both swelling and hematoma will compress and displace normal brain tissue.

Most often, hemorrhagic stroke is associated with high blood pressure, which stresses the artery walls until they break.

Another cause of hemorrhagic stroke is an aneurysm. This is a weak spot in an artery wall, which balloons out because of the pressure of the blood circulating inside the affected artery. Eventually, it can burst and cause serious harm. The larger the aneurysm is, the more likely it is to burst. It is unclear why people develop aneurysms, but genes may play a role, since aneurysms run in families.

Stroke can also be caused by the accumulation of a protein called amyloid within the artery walls, particularly in the elderly. This makes the arteries more prone to bleeding.

Amyloid protein is also implicated in the brain damage related to Alzheimer's disease, but the difference is that people with Alzheimers disease have amyloid accumulatation in the brain tissue instead of in the arteries. Therefore people with Alzheimers usually do not develop brain bleeding.

Some people with brain hemorrhage have abnormal connections between arteries and veins. Under normal circumstances, circulating blood travels through the arteries into the capillaries, where it provides nutrients and oxygen to the tissues. Once the blood has deposited the nutrients and oxygen, it is carried back to the heart from the capillaries via the veins.

In some people, however, a brain artery may connect directly to a vein, instead of going through the capillaries first. This is called an arterial-venous malformation (AVM). Since blood pressure in the arteries is much greater than in the veins, the veins may rupture, causing bleeding into the brain.