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Strokes in Women
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|What Is An Ischemic Stroke?
There are two types of strokes (image): an ischemic stroke and a hemorrhagic stroke. Ischemic strokes account for 80 percent of all strokes, hemorrhagic strokes make up the remaining 20 percent. Most commonly an ischemic stroke occurs when a blood clot forms in an artery in the neck (carotid artery) and blocks blood supply to the brain. In other instances the clot might form in another part of the body such as the heart and travel to the brain (this is called an embolus, a sort of traveling clot). If the blood is blocked for more than a few minutes, the brain cells start to die and permanent damage results. If the clot is short lived and resolves on its own naturally within a few minutes, it causes temporary symptoms of stroke. This is known as a mini stroke or transient ischemic attack (TIA). While TIAs are not as serious, they are an indication that a major stroke is brewing. Ischemic and hemorrhagic strokes are the leading cause of disability in the United States and the third leading cause of death after heart disease and cancer.
What Is The Difference Between A Stroke And A Heart Attack?
Strokes and heart attacks are two different conditions. A stroke is a brain attack, meaning the brain is under attack and not the heart. During a stroke, blood supply to the brain is restricted leading to death of brain muscle tissue. Depending on the severity of the attack, brain function can be permanently lost resulting in loss of control over different parts of the body. It is not uncommon for arms or legs to no longer to function after a stroke. A heart attack (image) on the other hand only affects the function of the heart, and permanent damage leads to loss of heart function - such as an inability to pump as well as it used to causing shortness of breath and fatigue (see heart attacks in women).
What Causes An Ischemic Stroke?
Causes of Strokes: There are two main types of ischemic stroke: an embolic and thrombotic stroke.
An embolic stroke occurs when a blood clot forms in another location in the body (usually the heart) and travels through the veins (either as one lump or in smaller fragments) to the brain. This type of clot is called an embolus. Once it arrives in the brain it eventually stops when it reaches a blood vessel too small to let it pass. This suddenly obstructs blood flow to the brain, and causes a stroke. A type of heart arrhythmia called atrial fibrillation (an irregular heart beat) seems to make the likelihood of clots more likely. Other times, having a hole in the heart makes it possible for a blood clot from the leg to cross through the heart and into the brain.
About 50 to 60 percent of all strokes are thrombotic strokes. A thrombotic stroke is where a clot forms directly in one of the blood vessels supplying the brain - such as the neck carotid artery (or vertebrobasilar and cerebral arteries). It is usually caused by the buildup of fatty deposits called atherosclerosis (image) in the artery which narrows the space through which blood can flow. A blood clot can build around the areas of the vessel damaged by atherosclerotic plaques. Thrombotic stroke may start in a large blood vessel and patients usually have symptoms of coronary heart disease and heart disease risk factors. A thrombotic stroke can also occur deep within the smaller blood vessels of the brain, this is technically referred to as lacunar infarction. This type of stroke is linked to chronic (long-term) high blood pressure. A less common cause is migraine headaches. In particularly severe cases a migraine can cause the blood vessels in the head to spasm, long enough for blood clots to form.
What Are The Symptoms Of Ischemic Stroke?
It not always possible to tell the difference between an ischemic stroke and a hemorrhagic stroke by listing the symptoms alone - that said studies show that ischemic strokes are more likely to occur suddenly (in comparison, with a hemorrhagic stroke the patient may notice the onset of symptoms gradually over a few hours, and they are more likely to experience vomiting). In emergency, a brain CT scan or MRI scan will be necessary to make an accurate diagnosis. A correct diagnosis is important because this determines the type of treatment used. Even then, not everyone experiences an ischemic stroke (or any stroke) in the same way. The symptoms will depend on which artery is blocked and what part of the brain is deprived of blood. However research shows symptoms that are commonly associated with ischemic stroke or mini stroke include sudden:
• Weakness or numbness of the face, arm or leg, particularly on one side of the body.
• Mental confusion, trouble understanding or speaking.
• Trouble walking, dizziness, loss of coordination or balance.
• Trouble seeing in one or both eyes.
• Severe headache with no identifiable cause.
Read also about the effects of stroke.
How Is It Diagnosed?
Patients should immediately be transported to a hospital for rapid evaluation (ideally a TIA clinic or other specialized unit). The following stroke diagnosis procedures are likely to be carried out:
Using MRI or CT scan technology to take internal images of the brain.
Vascular screening uses ultrasound technology to detect blood clots or narrowed arteries.
Cardiac Rhythm Assessment
The heart beat is monitored with an ECG for signs of atrial fibrillation.
An echocardiogram test will be used if an embolic stroke and cardiac causes are suspected.
If symptoms were present for less than 24 hours, a mini stroke is usually diagnosed.
How Is An Ischemic Stroke Treated?
Treatment is usually with a clot buster drug called TPA, also known as thrombolytic therapy. These are powerful medications which rapidly dissolve the blood clot causing the problem. To have any hope of real success treatment needs to be started within 3 hours of the stroke occurring. Typically only 3 to 5 percent of people arrive at hospital in time for TPA treatment within this timeframe. Fortunately new studies indicate that TPA may still have some effect after this 3 hour period. While an ischemic stroke causes the core area of the brain to stop functioning, a much larger area (called the ischemic penumbra) surrounding the core goes into idle mode. This means the penumbra area, although impaired, is not yet destroyed. It can survive for several hours in this state, meaning it can still be restored by TPA for up to 4.5 hours after the onset of symptoms (although TPA is only currently approved by the FDA for use for up to 3 hours after). In addition, if patients are taken to a major stroke center where angiograms on the arteries of the brain can be performed, clot busters can be given through catheters directly into the blocked artery for up to 6 hours after the onset of symptoms. Once the stroke has run its course and has been treated, the patient can leave hospital. Within 24 hours of leaving patients may be prescribed long-term aspirin therapy or antiplatelet medications to reduce the risk of further blood clots and subsequent strokes. People who have atrial fibrillation are usually given anticoagulant drugs such as warfarin to prevent blood clots from forming in the heart. Surgical procedures may be also be offered as treatment to restore blood flow more permanently where arteries are narrowed severely by long-term build up of atherosclerosis. See stroke treatment for more details. Read also about stroke rehabilitation.
Can It Be Prevented?
The best way to reduce your risk factors for ischemic stroke is to reduce your overall stroke risk factors (see stroke prevention). This includes eating a healthy diet, maintaining a healthy body weight, controlling cholesterol and blood pressure levels and not smoking.
What Is The Prognosis?
According to the Heart and Stroke Foundation, for every 100 people who have a stroke, about 15 will die (in other words an 85 percent survival rate). 10 will recover completely, 25 will recover with a minor disability, 40 are left with a moderate to severe impairment and 10 will be so severely disabled that they require long-term care. During the first few days of an ischemic stroke, doctors can not usually predict which patients will improve or worsen. People with one sided paralysis tend to have better chances of recovering function than both sided paralysis. Read more about: stroke recovery.