Stroke is the leading cause of serious, long-term disability in the United States, with about 6.5 million stroke survivors alive today. A stroke occurs when a blood vessel in the brain becomes blocked or bursts.
There are two types of stroke - hemorrhagic and ischemic. A hemorrhagic stroke occurs when brain arteries rupture and an ischemic stroke occurs when blood supply to part of the brain is cut off.
An ischemic stroke occurs when the blood supply is cut off from part of the brain. When this happens, the blood-deprived brain tissue loses its supply of oxygen and nutrients. When brain tissue is deprived of blood for more than three minutes, the brain tissue begins to die. In ischemic strokes, brain arteries become blocked by a clot or plaque and prevent blood from nourishing the brain.
Transient loss of neurological functions often occur before a full blown stroke, and as such, TIAs should be treated just as seriously. A TIA occurs when blood flow to a certain part of the brain is cut off for a short period of time, usually 15 minutes or less. Although TIA is a painless episode, it is an important warning sign.
Ischemic strokes tend to result from either clotting of an already narrowed vessel, much like in a typical heart attack, or from clots that formed elsewhere, and then lodge in the vessels that supply the brain.
The term hemorrhagic means flow (or torrent) of blood, referring to bleeding into or around the brain. These may also result in similar symptoms to an ischemic stroke. Subarachnoid, parenchymal, and intraventricular hemorrhages are the major subtypes, depending on where the bleeding is located. In hemorrhagic strokes, brain arteries rupture from high blood pressure, abnormal blood vessel walls, or from an aneurysm (an abnormal outpouching of a blood vessel) and cause blood to flood the brain, creating pressure that leads to significant brain injury.
A subarachnoid hemorrhage (a type of hemorrhagic stroke) is a situation where bleeding occurs in the subarachnoid space, an area between the covering of the brain (dura) and a second thinner layer (the arachnoid mater), and the thinnest layer around the brain itself. This space also normally contains a clear fluid called Cerebral Spinal Fluid.
While the most common cause of subarachnoid hemorrhage is probably from trauma, the most common cause of a subarachnoid hemorrhage not associated with traumatic injury is from a rupture of an aneurysm. Some more rare causes of subarachnoid hemorrhage include arteriovenous malformations, dural fistulae or shunts, as well as vasculitides of the cerebrovasculature.
Warning signs of stroke
Many warning signs indicate you may be suffering a possible stroke. Depending on the function of the part of the brain affected, the person suffering the stroke suddenly may become paralyzed, blind or unable to speak.
If you experience any of the major stroke warning signs listed below, call 911. It is important to get to a hospital immediately.
- Sudden loss of speech
- Slurred speech
- Sudden loss of vision
- Blurry or double vision
- Sudden paralysis
- Sudden weakness
- Sudden dizziness
- Sudden severe headache often accompanied by neck stiffness and vomiting
Remember that “time is brain.” The longer brain cells go without fresh blood and oxygen, the more likely the damage is to be irreversible. Areas of the brain that are getting barely enough blood, may go on to irreversible injury. The chances for survival and recovery improve when treatment begins within the first hours after a stroke has occurred.
Many factors increase the risk for stroke. Some factors can be controlled, while others cannot.
- High blood pressure: Strokes are 4 to 6 times more likely to occur in people with high blood pressure
- High cholesterol: People with high cholesterol are at double the risk of having a stroke
- Heart disease: Strokes are 6 times more likely to occur in people with heart disease
- Being overweight: Excess weight can lead to heart disease and high cholesterol, which, in turn, increases chances of having a stroke
- Heavy drinking increases the risk for stroke
- Smoking: Smokers have double the risk for stroke than nonsmokers
- Men are more likely to have strokes than women
- Blacks have a higher rate of stroke than other races
- Age: After age 55, there is an increased likelihood of having a stroke
- Diabetics are at a higher risk for stroke
- Those who have a family history of strokes or a prior stroke are at higher risk for having a stroke
Are you or a loved one at risk?
Many warning signs indicate you may be suffering a stroke. Depending on the function of the part of the brain affected.
How do you reduce your risk?
- Control your blood pressure
- Find out if you have heart disease, especially an irregular heartbeat known as atrial fibrillation (AF)
- Don’t smoke
- Find out if you have a diseased carotid artery (arteries that provide blood flow to the head)
- Lower your cholesterol
- Limit your alcohol use
- Control your weight
- If you have diabetes, control your glucose level
For patients with risk factors, medications for blood pressure, diabetes and high cholesterol are important prevention measures. Smoking must stop. A person who has had transient ischemic attacks (mini strokes) or a stroke may be treated with aspirin or other antiplatelet or anticoagulant drugs to reduce the risk of another attack. A type of surgery called carotid endarterectomy is sometimes recommended to reduce the risk for a major stroke. In this procedure, the fatty deposits in the carotid artery that block blood flow to the brain are removed. Less invasive options for opening blocked carotid arteries include carotid artery stenting and other neuroendovascular procedures. Similarly, patients with fatty deposits around vessels of the brain may also have increased risk of stroke, and may be treated by stenting and/or angioplasty.
Stroke treatment and management
Immediate treatment of a stroke may limit brain damage. Thrombolytic agent or “clot buster” medication in the veins must be given within the first three hours of the onset of stroke symptoms. In select patients, additional maneuvers with novel neurointerventional devices may be used to open clogged cerebral vessels. Time remains the single most important factor and it is critical to get to the hospital quickly if you experience stroke symptoms. The fastest way is to call 911.