Cerebrovascular Accident (1) Stroke
Cervical Cancer: Diagnosis and Assessment
August 2, 2018
Cerebrovascular Accident (1) Stroke
Stroke in medical terminology is also referred to as a cerebrovascular accident.
As the combination of the nomenclature suggests, it is a sudden event in the blood vessels of the brain that soon lead to the loss of some neurological functions in the affected individual.
Commonly, the obvious loss of nerves’ function is seen in the affected individuals as paralysis of the limbs, loss of speech, loss of facial expression, inability to write among other lost neurological functions.
The carotid arteries come up through either side of the front of the neck. (The pulsation of a carotid artery can be felt by placing fingertips gently against either side of the neck right under the jaw.)
The basilar artery forms at the base of the skull from the vertebral arteries, which run up along the spine and come up through the neck.
A reduction of blood flow for even a short period of time can be disastrous and is the primary cause of a stroke. A stroke has the same relationship to the brain as a heart attack does to the heart. Both result from a blockage (or rupture of) in a blood vessel that interrupts the supply of oxygen to cells, resulting in the death of vital tissue.
Consequently, a stroke is usually defined as two types:
Ischemic (caused by a blockage in an artery).
Hemorrhagic (caused by a tear in the artery's wall that produces bleeding in the brain).
The consequences of a stroke, the type of functions affected, and the severity, depend on where in the brain the blockage has occurred and the extent of the damage.
Thrombotic stroke. Thrombi are blood clots that form within one of the brain's arteries.
Embolic stroke. Emboli are clots that form elsewhere but are carried by the blood to eventually lodge in an artery in the brain.
An embolic stroke is usually caused by a dislodged blood clot that has traveled through the blood vessels until it becomes wedged in an artery. Emboli account for 60% of stroke and may be due to various conditions:
Parenchymal, or cerebral, hemorrhage stroke occurs within the brain. They account for more than half of hemorrhagic stroke. They are most often the result of hypertension exerting excessive pressure on arterial walls already damaged by atherosclerosis. Heart attack patients who have been given drugs to break up blood clots or blood-thinning drugs have a slightly elevated risk of this type of stroke.
Subarachnoid hemorrhagic stroke , the other major hemorrhagic stroke, occur in the tissues surrounding the brain. They are usually caused by the rupture of an aneurysm, a weakened blood vessel wall, which is often an inherited trait.
Arteriovenous malformation (AVM) is an abnormal connection between arteries and veins. If it occurs in the brain and ruptures, it can also cause a hemorrhagic stroke.
Transient ischemic attacks, however, are the warning signals of ischemic stroke as angina is the red flag for a heart attack. About 5% of those who experience TIAs go on to suffer a stroke within a month, and without treatment, a third will have stroke within five years. In fact, because of the relationship between atherosclerosis, coronary artery disease, and stroke, TIAs are also warning signs for a heart attack.
One of two major arteries is usually involved in a transient ischemic attack, either the carotid or basilar arteries:
Symptoms of TIAs in the Carotid Arteries: the carotid arteries start at the aorta and lead up through the neck around the windpipe and on into the brain. They are the more commonly involved sites. When TIAs occur here, they may cause symptoms in either the retina of the eye or the cerebral hemisphere (the large top part of the brain):
When oxygen to the eye is reduced, people describe the visual effect as a shade being pulled down. People may develop poor night vision.
When the cerebral hemisphere is affected by a TIA, a person can experience problems with speech and partial and temporary paralysis, tingling, and numbness, usually on one side of the body.
Symptoms of Transient Ischemic Accidents in the Basilar Artery The other major site of trouble, the basilar artery, is formed at the base of the skull from the vertebral arteries, which run up along the spine. When TIAs occur here, both hemispheres (sides) of the brain may be affected so that symptoms occur on both sides of the body. Some include the following:
Temporarily dim, gray, blurry, or lost vision in both eyes.
Tingling or numbness in the mouth, cheeks, or gums.
Headache at the back of the head.
Dizziness.
Nausea and vomiting.
Difficulty swallowing.
Inability to speak clearly.
Weakness in the arms and legs, sometimes causing a sudden fall.
When thrombosis, a blood clot that has formed in a narrowed artery, causes the stroke, the onset usually occurs more gradually, over minutes to hours. On rare occasions it progresses over days to weeks. So called Stroke in evolution.
The blood clot usually affects the opposite side of the body from its location in the brain, with possible loss of feeling on one side of the face, in an arm or leg, or blindness in one eye.
Speech problems can occur if the left hemisphere of the brain is involved. In some people, mostly those who are left-handed, speech can be affected by a clot on the right side of the brain.
The stroke victim may be unable to express thoughts verbally or to understand spoken words.
They may experience major seizures and possibly coma.
Subarachnoid Hemorrhage: When the hemorrhage is a subarachnoid type, warning signs may occur from the leaky blood vessel a few days to a month before the aneurysm fully develops and ruptures. Warning signs may include: abrupt headaches; nausea and vomiting; sensitivity to light; various neurologic abnormalities.
When the aneurysm ruptures, the victim may experience the following: a terrible headache during sleep or at wake-up time; neck stiffness; vomiting; altered states of consciousness.
The eyes may become fixed in one direction or lose vision.
Stupor, rigidity, and coma can result.
Commonly, the obvious loss of nerves’ function is seen in the affected individuals as paralysis of the limbs, loss of speech, loss of facial expression, inability to write among other lost neurological functions.
The basic physiology
Blood Flow Blockage: The brain receives about 25% of the body's oxygen, but it cannot store it. Brain cells require a constant supply of oxygen to stay healthy and function properly. Blood, then, needs to be supplied to the brain continuously through two main arterial systems:The carotid arteries come up through either side of the front of the neck. (The pulsation of a carotid artery can be felt by placing fingertips gently against either side of the neck right under the jaw.)
The basilar artery forms at the base of the skull from the vertebral arteries, which run up along the spine and come up through the neck.
A reduction of blood flow for even a short period of time can be disastrous and is the primary cause of a stroke. A stroke has the same relationship to the brain as a heart attack does to the heart. Both result from a blockage (or rupture of) in a blood vessel that interrupts the supply of oxygen to cells, resulting in the death of vital tissue.
Consequently, a stroke is usually defined as two types:
Ischemic (caused by a blockage in an artery).
Hemorrhagic (caused by a tear in the artery's wall that produces bleeding in the brain).
The consequences of a stroke, the type of functions affected, and the severity, depend on where in the brain the blockage has occurred and the extent of the damage.
Ischemic Stroke
Ischemic stroke are by far the more common type, causing 80% of all. Ischemia means the deficiency of oxygen in vital tissues. Ischemic stroke are caused by blood clots that are usually one of two types:Thrombotic stroke. Thrombi are blood clots that form within one of the brain's arteries.
Embolic stroke. Emboli are clots that form elsewhere but are carried by the blood to eventually lodge in an artery in the brain.
An embolic stroke is usually caused by a dislodged blood clot that has traveled through the blood vessels until it becomes wedged in an artery. Emboli account for 60% of stroke and may be due to various conditions:
Hemorrhagic stroke
About 20% of stroke, occur from hemorrhage (sudden bleeding) in the brain. Hemorrhagic stroke may be categorized by how and where they occur.Parenchymal, or cerebral, hemorrhage stroke occurs within the brain. They account for more than half of hemorrhagic stroke. They are most often the result of hypertension exerting excessive pressure on arterial walls already damaged by atherosclerosis. Heart attack patients who have been given drugs to break up blood clots or blood-thinning drugs have a slightly elevated risk of this type of stroke.
Subarachnoid hemorrhagic stroke , the other major hemorrhagic stroke, occur in the tissues surrounding the brain. They are usually caused by the rupture of an aneurysm, a weakened blood vessel wall, which is often an inherited trait.
Arteriovenous malformation (AVM) is an abnormal connection between arteries and veins. If it occurs in the brain and ruptures, it can also cause a hemorrhagic stroke.
Low Blood Pressure (Hypotension) can cause a stroke
Less often, blood pressure that is too low can reduce oxygen supply to the brain and cause a stroke. This can occur from a heart attack, a major bleeding episode, an overwhelming infection, or rarely, from surgical anesthesia or from overtreatment of high blood pressure.Symptoms Of A Stroke
People at risk and partners or caretakers of people at risk for stroke should be aware of the general symptoms, and the stroke victim should get to the hospital as soon as possible after these warning signs appear. It is particularly important for people with migraines or frequent severe headaches to understand how to distinguish between their usual headaches and symptoms of stroke.Transient Ischemic Attacks (TIAs)
TIAs are mini-ischemic stroke, usually caused by tiny emboli that lodge in an artery and then quickly break up and dissolve. The mental or physical disturbances resulting from TIAs generally clear up in less than a day, with nearly all symptoms resolving in less than an hour. There is no residual damage.Transient ischemic attacks, however, are the warning signals of ischemic stroke as angina is the red flag for a heart attack. About 5% of those who experience TIAs go on to suffer a stroke within a month, and without treatment, a third will have stroke within five years. In fact, because of the relationship between atherosclerosis, coronary artery disease, and stroke, TIAs are also warning signs for a heart attack.
One of two major arteries is usually involved in a transient ischemic attack, either the carotid or basilar arteries:
Symptoms of TIAs in the Carotid Arteries: the carotid arteries start at the aorta and lead up through the neck around the windpipe and on into the brain. They are the more commonly involved sites. When TIAs occur here, they may cause symptoms in either the retina of the eye or the cerebral hemisphere (the large top part of the brain):
When oxygen to the eye is reduced, people describe the visual effect as a shade being pulled down. People may develop poor night vision.
When the cerebral hemisphere is affected by a TIA, a person can experience problems with speech and partial and temporary paralysis, tingling, and numbness, usually on one side of the body.
Symptoms of Transient Ischemic Accidents in the Basilar Artery The other major site of trouble, the basilar artery, is formed at the base of the skull from the vertebral arteries, which run up along the spine. When TIAs occur here, both hemispheres (sides) of the brain may be affected so that symptoms occur on both sides of the body. Some include the following:
Temporarily dim, gray, blurry, or lost vision in both eyes.
Tingling or numbness in the mouth, cheeks, or gums.
Headache at the back of the head.
Dizziness.
Nausea and vomiting.
Difficulty swallowing.
Inability to speak clearly.
Weakness in the arms and legs, sometimes causing a sudden fall.
Symptoms of Major Ischemic stroke
If the stroke is caused by a large embolus that has traveled to and lodged in an artery in the brain, the onset is sudden. Headache and seizures can occur within seconds of the blockage.When thrombosis, a blood clot that has formed in a narrowed artery, causes the stroke, the onset usually occurs more gradually, over minutes to hours. On rare occasions it progresses over days to weeks. So called Stroke in evolution.
The symptoms for a major ischemic stroke are extremely variable
As outlined above, early symptoms can be identical to those of a transient ischemic attack, since, in both cases, the clot can produce a blockage in a branch of the carotid or basilar arteries. However, In the case of a TIA, however, the symptoms resolve.The blood clot usually affects the opposite side of the body from its location in the brain, with possible loss of feeling on one side of the face, in an arm or leg, or blindness in one eye.
Speech problems can occur if the left hemisphere of the brain is involved. In some people, mostly those who are left-handed, speech can be affected by a clot on the right side of the brain.
The stroke victim may be unable to express thoughts verbally or to understand spoken words.
They may experience major seizures and possibly coma.
Symptoms of Hemorrhagic Stroke
Cerebral Hemorrhage Symptoms: Symptoms of a cerebral, or parenchymal, hemorrhage typically begin very suddenly and evolve over several hours and include: headache; nausea and vomiting; altered mental states.Subarachnoid Hemorrhage: When the hemorrhage is a subarachnoid type, warning signs may occur from the leaky blood vessel a few days to a month before the aneurysm fully develops and ruptures. Warning signs may include: abrupt headaches; nausea and vomiting; sensitivity to light; various neurologic abnormalities.
When the aneurysm ruptures, the victim may experience the following: a terrible headache during sleep or at wake-up time; neck stiffness; vomiting; altered states of consciousness.
The eyes may become fixed in one direction or lose vision.
Stupor, rigidity, and coma can result.
