subarachnoid

A stroke happens when there is a loss of blood flow to part of the brain. Your brain cells cannot get the oxygen and nutrients they need from blood, and they start to die within a few minutes. This can cause lasting brain damage, long-term disability, or even death.

There are two main types of strokes, ischemic and hemorrhagic. A hemorrhagic stroke is less common but often more severe. It occurs when a blood vessel in the brain bursts, causing bleeding (hemorrhage) in or around the brain. This bleeding increases pressure inside the skull and damages brain tissue. Within minutes, brain cells begin to die.

Hemorrhagic strokes are classified by where the bleeding happens:

• Intracerebral hemorrhage. Bleeding occurs directly into the brain tissue. This is the most common type of hemorrhagic stroke.
• Subarachnoid hemorrhage. Bleeding occurs in the space between the brain and the thin layers of tissues covering it. This often happens when a weak spot in an artery (called an aneurysm) bursts on the brain's surface.

Common causes include:

• Aneurysm. A bulge or "ballooning" in a weakened artery wall that can burst.
• Arteriovenous malformation (AVM). A tangled group of abnormal blood vessels that can rupture inside the brain.
• High blood pressure (hypertension). Over time, it can weaken blood vessel walls and increase the risk of them breaking open.
• Head trauma. Brain injury can cause bleeding.

Stroke symptoms often happen suddenly. They include:

• Sudden numbness or weakness of the face, arm or leg (especially on one side of the body)
• Sudden confusion, trouble speaking, or understanding speech
• Sudden trouble seeing in one or both eyes
• Sudden trouble walking, dizziness, loss of balance or coordination
• Sudden severe headache with no known cause

The F.A.S.T. test can help you remember what to look for if you think someone is having a stroke. Think "FAST" and look for:

• Face drooping on one side when smiling.
• Arm weakness occurs when the arms are raised, and one arm drifts downward.
• Speech is slurred or strange.
• Time to call 911.

To make a diagnosis, your health care provider may do a physical exam, ask about your symptoms and medical history, and use imaging tests to check for bleeding in your brain.

It is important to treat strokes as quickly as possible. For a hemorrhagic stroke, the first step is to find the cause of bleeding in the brain and stop it. Treatment may involve medicines or, in some cases, surgery to stop the bleeding or relieve pressure on the brain.

After the stroke, rehabilitation can help people recover lost abilities and regain independence.

The best way to prevent stroke is by making heart-healthy lifestyle changes to lower your risk. If lifestyle changes aren't enough, your provider may prescribe medicine to help manage your risk factors.

NIH: National Institute of Neurological Disorders and Stroke

A brain aneurysm is an abnormal bulge or "ballooning" in the wall of an artery in the brain. They are sometimes called berry aneurysms because they are often the size of a small berry. Most brain aneurysms produce no symptoms until they become large, begin to leak blood, or burst.

If a brain aneurysm presses on nerves in your brain, it can cause signs and symptoms. These can include:

• A droopy eyelid
• Double vision or other changes in vision
• Pain above or behind the eye
• A dilated pupil
• Numbness or weakness on one side of the face or body

Treatment depends on the size and location of the aneurysm, whether it is infected, and whether it has burst. If a brain aneurysm bursts, symptoms can include a sudden, severe headache, nausea and vomiting, stiff neck, loss of consciousness, and signs of a stroke. Any of these symptoms requires immediate medical attention.

NIH: National Heart, Lung, and Blood Institute

Bleeding is the loss of blood. It can be external, or outside the body, like when you get a cut or wound. It can also be internal, or inside the body, like when you have an injury to an internal organ. Some bleeding, such as gastrointestinal bleeding, coughing up blood, or vaginal bleeding, can be a symptom of a disease.

Normally, when you are injured and start bleeding, a blood clot forms to stop the bleeding quickly. Afterwards, the clot dissolves naturally. To be able to make a clot, your blood needs blood proteins called clotting factors and a type of blood cell called platelets. Some people have a problem with clotting, due to another medical condition or an inherited disease. There are two types of problems:

• Your blood may not form clots normally, known as a bleeding disorder. This happens when your body does not make enough platelets or clotting factors, or they don't work the way they should.
• Your blood may make too many clots, or the clots may not dissolve properly

Sometimes bleeding can cause other problems. A bruise is bleeding under the skin. Some strokes are caused by bleeding in the brain. Severe bleeding may require first aid or a trip to the emergency room.