• A stroke occurs when part of the brain loses its blood supply and stops working, thus causing the body’s part that the injured brain controls to stop working.
• A stroke also is called a cerebrovascular accident, CVA, or “brain attack.”
• The types of strokes include:
○ Ischemic stroke (part of the brain loses blood flow)
○ Hemorrhagic stroke (bleeding occurs within the brain)
• Transient ischemic attack, TIA, or mini-stroke (The stroke symptoms resolve within minutes, but may take up to 24 hours on their own without treatment. This is a warning sign that a stroke may occur soon.)
• A stroke is a medical emergency. The affected individual, family, friends, or bystanders need to call 9-1-1 (activate EMS) to access emergency care.
• There is only a 3 to 4 1/2 hour window to use clot-busting drugs (thrombolytics) to restore blood supply to the affected part of the brain from the onset of symptoms.
• Remember FAST if you think someone might be having a stroke:
○ Face drooping
○ Arm weakness
○ Speech difficulty
○ Time to call 9-1-1
• Causes of strokes include ischemia (loss of blood supply) or hemorrhage (bleeding) in the brain.
• People at risk for stroke include high blood pressure, high cholesterol, diabetes, and those who smoke. People with heart rhythm disturbances, especially atrial fibrillation, are also at risk.
• Stroke is diagnosed by the patient’s symptoms, history, and blood and imaging tests.
• Depending on the situation, including the patient’s neurologic examination and severity of a stroke, mechanical thrombectomy to remove a blood clot within a brain artery may occur 24 hours after the symptoms. This procedure is not available at all hospitals and not appropriate for all stroke patients.
• You can prevent stroke by quitting smoking, controlling blood pressure, maintaining a healthy weight, eating a healthy diet, and exercising regularly.
• The prognosis and recovery for a person that has suffered a stroke depend upon the location of the injury to the brain.
The symptoms of a stroke vary depending upon the brain’s area affected by a lack of oxygen. All strokes involve symptoms that relate to impairment of nerve function. The symptoms typically arise suddenly and most commonly occur on one side of the body. Symptoms and signs of stroke can include:
• tingling, or
• Vision loss or changes.
Confusion, changes in the level of consciousness, trouble speaking, trouble understanding speech, vertigo, and balance problems are other common symptoms. Headache, nausea, and vomiting sometimes accompany a stroke, mainly when the stroke involves bleeding inside the brain.
A stroke, also known as a cerebrovascular accident or CVA, is when part of the brain loses its blood supply. This loss of blood supply can be ischemic because of lack of blood flow, or hemorrhagic because of bleeding into brain tissue. A stroke is a medical emergency because strokes can lead to death or permanent disability. There are opportunities to treat ischemic strokes, but that treatment needs to be started in the first few hours after a stroke’s signs begin. The patient, family, or bystanders, should call 9-1-1 and activate emergency medical services immediately should a stroke be suspected.
A transient ischemic attack (TIA or mini-stroke) describes an ischemic stroke short-lived where the symptoms resolve spontaneously. This situation also requires an emergency assessment to try to minimize the risk of a future stroke. By definition, a stroke would be classified as a TIA if all symptoms resolved within 24 hours.
The blockage of an artery in the brain by a clot (thrombosis) is the most common cause of a stroke. The part of the brain supplied by the clotted blood vessel is then deprived of blood and oxygen. As a result of the deprived blood and oxygen, the cells of that part of the brain die, and the part of the body that it controls stops working. Typically, a cholesterol plaque in one of the brain’s small blood vessels ruptures and starts the clotting process.
Risk factors for narrowed blood vessels in the brain are the same as those that cause narrowing blood vessels in the heart and heart attack (myocardial infarction).
These risk factors include:
• high blood pressure (hypertension),
• high cholesterol,
• diabetes, and
Another type of stroke may occur when a blood clot or a piece of atherosclerotic plaque (cholesterol and calcium deposits on the wall of the inside of the heart or artery) breaks loose, travels through the bloodstream, and lodges in an artery in the brain. When blood flow stops, brain cells do not receive the oxygen and glucose they require to function, and a stroke occurs. This type of stroke is referred to as an embolic stroke. For example, a blood clot might initially form in the heart chamber due to irregular heart rhythm, like atrial fibrillation. Usually, these clots remain attached to the inner lining of the heart. Still, occasionally they can break off, travel through the bloodstream (embolize), block a brain artery, and cause a stroke. An embolism, either plaque or clot, may also originate in a large artery and then travel downstream clog a small artery within the brain.
A cerebral hemorrhage occurs when a blood vessel in the brain ruptures and bleeds into the surrounding brain tissue. A cerebral hemorrhage (bleeding in the brain) causes stroke symptoms by depriving blood and oxygen to parts of the brain in various ways. Blood flow is lost to some cells. Additionally, blood is very irritating and can cause swelling of brain tissue (cerebral edema). Edema and blood accumulation from a cerebral hemorrhage increases pressure within the skull. It causes further damage by squeezing the brain against the bony skull. This further decreases blood flow to brain tissue and its cells.
In a subarachnoid hemorrhage, blood accumulates in the space beneath the arachnoid membrane that lines the brain. The blood originates from an abnormal blood vessel that leaks or ruptures. Often this is from an aneurysm (an abnormal ballooning out of the blood vessel). Subarachnoid hemorrhages usually cause a sudden severe headache, nausea, vomiting, light intolerance, and stiff neck. If not recognized and treated, significant neurological consequences, such as coma and brain death, may occur.
Another rare cause of stroke is vasculitis. The blood vessels become inflamed, causing decreased blood flow to parts of the brain.
There appears to be a very slight increased occurrence of stroke in people with migraine headaches. The mechanism for migraine or vascular headaches includes the narrowing of the brain blood vessels. Some migraine headache episodes can even mimic stroke with loss of function of one side of the body or vision or speech problems. Usually, the symptoms resolve as the headache resolves.
Strokes are usually classified by what mechanism caused the blood supply loss, either ischemic or hemorrhagic. A stroke may also be described by what part of the brain was affected (for example, a right temporal stroke) and what part of the body stopped working (stroke affecting the left arm).
An ischemic stroke is caused by an artery in the brain being obstructed or blocked, preventing oxygen-rich blood from being delivered to brain cells. The artery can be blocked in a couple of ways. In a thrombotic stroke, an artery can narrow over time because of cholesterol buildup, called plaque. If that plaque ruptures, a clot is formed at the site and prevents blood from passing to brain cells downstream, deprived of oxygen.
In an embolic stroke, the artery is blocked because of debris or a clot that travels from the heart or another blood vessel. An embolus or embolism is a clot, a piece of fatty material, or other objects that travel within the bloodstream that lodges in a blood vessel to cause an obstruction.
Blood clots that embolize usually arise from the heart. The most common cause of these blood clots is a heart arrhythmia called atrial fibrillation. The upper chambers of the heart, the atria, do not beat in an organized rhythm. Instead, the chaotic electrical rhythm causes the atria to jiggle like a bowl of Jell-O. While blood still flows to the ventricles (the heart’s lower chambers) to be pumped to the body, some blood along the atrium’s inner walls can form small blood clots. If a clot breaks off, it can travel or embolize to the brain, block blood flow to a part of the brain and cause a stroke.
The carotid arteries are two large blood vessels that provide the brain with blood supply. These arteries can narrow or develop stenosis, with cholesterol plaque that may build up over time. The plaque’s surface is irregular, and bits of debris can break off and embolize to the brain to block blood vessels downstream and deprive brain cells of oxygen-rich blood.
When a blood vessel leaks and spills blood into brain tissue, those brain cells stop working. The bleeding or hemorrhage is often due to poorly controlled high blood pressure that weakens an artery’s wall over time. Blood may also leak from an aneurysm, a congenital weakness or ballooning of an artery wall, or an AVM (arteriovenous malformation). In this congenital abnormality, an artery and vein connect incorrectly. The bleeding can form a hematoma that directly damages brain cells and may also cause swelling that further pressure surrounding brain tissue.
Describing a stroke by anatomy and symptoms
Four major arteries supply the brain with blood.
• The right and left carotid artery are located in the front of the neck, and their pulse can be felt with the fingers.
• The right and left vertebral arteries are encased in the bone as they run through the neck’s vertebrae. As the two enter the brain, they join to form the basilar artery.
• The carotid arteries and the vertebrobasilar arteries join to form the Circle of Willis at the brain’s base. From this circle, arteries branch off to supply the brain with blood.
The left side of the brain controls the right side of the body and vice versa. Speech tends to be located in the dominant hemisphere, most often the left brain.
The anterior and middle cerebral arteries provide blood supply to the front two-thirds of the brain, including the frontal, parietal, and temporal lobes. These brain control parts control voluntary body movement, sensation, speech and thought, personality, and behavior.
The vertebral and basilar arteries are considered the posterior circulation and supply the occipital lobe where vision is located, the cerebellum that controls coordination and balance, and the brainstem responsible for the unconscious brain functions that include blood pressure, breathing, and wakefulness.
Strokes may be described based upon the body’s function that is lost and by the area of the brain that is affected. Most commonly, in strokes that involve the brain, the symptoms involve either the right or left side of the body. In strokes that affect the brainstem or the spinal cord, symptoms may present on both sides of the body.
Strokes may affect the motor function or the ability for the body to move. Part of the body may be affected, like the face, a hand, or an arm. An entire side of the body may be affected (for example, the left part of the face, left arm, and left leg). Weakness on one side of the body is called hemiparesis (Hemi = half + paresis = weak), and paralysis is hemiplegia (Hemi = half + plegia = paralysis).
Similarly, sensory function — the ability to feel — can affect the face, hand, arm, trunk, or combination.
Other symptoms like speech, vision, balance, and coordination help locate the part of the brain that has stopped working and helps the health care professional make the clinical diagnosis of stroke. This is an essential concept since not all loss of neurologic function is due to stroke. Suppose anatomy and physiology do not match the loss of body function. In that case, other diagnoses may be considered to affect both the brain and body.
A lacunar stroke describes the blockage of a single tiny penetrating artery branch in the brain. The area of the involved brain is small. However, it can still cause significant neurologic deficits, just like a stroke involving a larger blood vessel and more brain tissue. However, in some cases, the stroke is silent, meaning that no obvious body function is lost. An old lacunar stroke can be seen as an incidental finding on a CT or MRI scan of the head that might be done for other reasons. The term lacune means empty space, and a tiny space of an old lacunar stroke can be seen on imaging where brain tissue has been lost.
There may be no warning signs of a stroke until it occurs. It is why high blood pressure (hypertension), one of the risk factors for stroke, is called the silent killer.
Some patients may experience a transient ischemic attack (TIA) that can be thought of as a stroke that has resolved itself. The symptoms may be mild or dramatic and can mimic a stroke with weakness, numbness, facial droop, and speech difficulties. Still, these symptoms may only last a few minutes. TIAs should not be ignored since they may offer an opportunity to look for potentially reversible or controllable stroke causes. As well, there is no guarantee that the symptoms of stroke will resolve on their own. For that reason, a TIA should be considered an emergency, and medical care should be accessed immediately.
Amaurosis fugax describes the temporary loss of vision in one eye because of an embolus of a blood clot or debris to the artery that supplies the eye. While it only involves vision, this situation should be considered a type of TIA.
Stroke symptoms depend upon the brain’s area and have stopped working due to its blood supply loss. Often, the patient may present with multiple symptoms, including the following:
• Acute change in the level of consciousness or confusion
• Acute onset of weakness or paralysis of half or part of the body
• Numbness of one half or part of the body
• Partial vision loss
• Double vision
• Difficulty speaking or understanding speech
• Difficulty with balance and vertigo
The symptoms of ischemic and hemorrhagic stroke may be the same. Still, patients with hemorrhagic stroke may also complain more of headache and vomiting.
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