Cerebrovascular accident is the medical term for an event more commonly known as “stroke” and for the purpose of this assignment the word “stroke” will be used. A stroke is a sudden event affecting the blood vessels of the brain. Stroke is the third leading cause of death in the United States and the second leading cause of death in the world (Lopez et al, 2001).
With treatment, stroke prevention and therapy are advancing all the time. The outlook for those who suffer ischemic or subarachnoid episodes continues to improve. The key to all success where stroke is concerned is early diagnosis and subsequent treatment. An individual is more at risk of suffering a stroke if they have:
- Suffered a stroke previously
- Suffered a myocardial infarction
- Had a transient ischemic attack (mini-stroke)
- Have an artificial heart valve
- Suffer uncontrolled hypertension
- Are diabetic
- Are known to have raised cholesterol
- Have a family history of strokes
Any one or combination of the above can provide predisposing factors for having a stroke. Patients who suffer these types of risk factors or conditions are encouraged to carry on them some form of identification of the fact, so that in the event of a medical emergency or unexpected hospital admission physicians may be able to determine a diagnosis or cause for the problem more quickly. There are several different types of stroke all with different causes and presenting symptoms, this learning material focuses on the three main types of stroke:
Ischemic Stroke Ischemic stroke is known to be the most common type accounting for around 80% of all strokes. It is caused by a clot or other blockage within an artery leading to the brain (Stroke Center, date unknown). The presenting symptoms of an ischemic stroke include:
- Muscle weakness
- Reduced/lost sensation on one side of the body
- Dysphasia ( difficulty speaking)
- Visual disturbance
- Loss of co-ordination and balance
Diagnosis is usually based on symptoms and results of physical examination, imaging tests and blood tests (Merck Manuals, 2007). There is no blood test or electrocardiogram (ECG) specific for stroke, and CT scans may be entirely normal for up to six hours after acute onset of stroke. Thus the neurologist becomes an irreplaceable member of the team to acutely evaluate stroke patients (Llinas, 2006). A condition called “atherosclerosis” is commonly the cause of the blockage of the blood vessel, and atherosclerosis pertains to fatty deposits that accumulate on the walls of the vessels causing a disruption or total blockage to the much needed blood supply to the brain. These fatty deposits can cause two types of obstruction:
Cerebral thrombosis – this refers to a thrombus (blood clot) that develops at the clogged part of the vessel.
Cerebral embolism – this refers generally to a blood clot that forms at another location in the circulatory system, usually the heart and large arteries of the upper chest and neck. A portion of the blood clot breaks loose, enters the bloodstream and travels through the brains blood vessels until it reaches vessels too small to let it pass. A second important cause of embolism is an irregular heartbeat, known as atrial fibrillation. It creates conditions where clots can form in the heart, dislodge and travel to the brain. (American Stroke Association, 2008) Rapid intervention is required to provide optimal treatment for the patient who has suffered an acute ischemic stroke. Early assessment and rapid intervention are crucial to avoid the risk of permanent disability or at worse death. The use of rapid assessment and early intervention is essential in all presenting cases. Thrombolysis with tissue plasminogen activator has been labeled for the treatment of acute ischemic stroke, but it must be given within three hours of stroke onset. However, fibrinolytic therapy can be given safely to only a fraction of patients with acute stroke, and more broadly applicable therapies are needed. Recent evidence does not support the routine use of heparin in patients with acute stroke, and early use of aspirin offers only modest benefit (Benavente and Hart, 1999). The use of Aspirin to treat those who have had an ischemic stroke is not uncommon, Aspirin works in such a way as to thin the blood to sufficient levels to avoid the formation of blood clots that can cause such events.
Intra-cerebral Hemorrhage (ICH) An intra-cerebral hemorrhage is one of two types of hemorrhagic stroke and is a type of stroke caused by the sudden rupture of an artery within the brain. Blood is then released into the brain, compressing brain structures (Stroke Center, date unknown). The most common cause of intra-cerebral hemorrhage is hypertension. Difficulties arise when individuals experience high blood pressure without knowledge of the fact, as more often than not hypertension does not display any adverse symptoms. There are some less common causes of intra-cerebral hemorrhage and these include:
- Trauma (particularly head injury)
- Infection (systemic)
- Abnormalities with individual blood vessels
- Blood clotting disorders
Oral anticoagulation is another factor that contributes to the increasing incidence of intra-cerebral hemorrhage. As the population continues to age, the number of indications for long-term anticoagulation continue to increase (Ansell et al, 2001). Because of the high mortality rate of patients who have suffered intra-cerebral hemorrhage often is the case that anticoagulation therapy is avoided due to possible undesirable effects such as ICH. Intra-cerebral hemorrhages tend to begin abruptly and the patient will usually experience a severe headache. Other presenting symptoms may also be:
- Weakness, paralysis or loss of sensation usually affecting one side of the body only.
- Slurred speech
- Confusion or altered level of comprehension
- Loss of consciousness
Brain CT or MRI scan is the popular diagnostic tool in the case of ICH. Results are quick and conclusive therefore allowing management of the problem to begin without delay. At this current time there is no FDA approved treatment for intra-cerebral hemorrhage, unlike other types of stroke. Treatment depends on the location, cause, and extent of the hemorrhage. Surgery may be needed, especially if there is bleeding in the cerebellum. Surgery may also be performed to repair or remove structures causing the bleed such as a cerebral aneurysm or arteriovenous malformation (Dr Koop, 2006). The prognosis for intra-cerebral hemorrhage is more likely to be fatal than that of ischemic stroke. Bleeding is usually more severe and damage to the brain profound. Where death does not occur, there is nearly always depleted brain function.
Subarachnoid Hemorrhage (SAH) A subarachnoid hemorrhage is also a type of stroke caused by the sudden rupture of an artery. This type of stroke is the second type of “hemorrhagic stroke”. A subarachnoid hemorrhage differs slightly from an intracerebral hemorrhage in that the location of the rupture leads to blood filling the space surrounding the brain rather than inside of it (Stroke Center, date unknown). The most common cause of subarachnoid hemorrhage is abnormalities in the blood arteries at the base of the brain. These are called “aneurysms”. The arteries swell and become weak they can then rupture causing the hemorrhage to occur. Known risk factors for subarachnoid hemorrhage include:
- Putative factors such as: increasing age, female gender, black race, alcohol abuse, binge drinking.
- Increased risk with high body mass index has been suggested.
And causative factors include:
- Vascular malformations of the brain or spinal cord
- Blood dyscrasias
- Less commonly reported: tumors, infection and vasculopathies.
(Neuroland, date unknown)
When an intracranial aneurysm ruptures into the subarachnoid compartment, it causes a subarachnoid hemorrhage (SAH). An estimated 10% of SAH cases result in sudden death due to the rapid and marked increases in intracranial pressure caused by the ruptured aneurysm (Mayo Foundation for Medical Education and Research, 2006). Rapid diagnosis is essential in all cases of SAH, as treatment is possible even if the outcome is not always a positive one. Head CT scan is the commonest diagnostic imaging used in suspected cases of SAH. Not only is the test one which is easy to arrange and quick to perform it also gives clear and concise data on the extent of damage, if any to the brain. In cases where CT brain appears normal a lumbar puncture would be the next test as in some cases blood can be detected in the spinal fluid obtained during the test.
There are varying types of symptoms of a subarachnoid hemorrhage however acute onset of severe headache is the most common. This is often associated with vomiting, and in serious cases coma occurs soon after the cerebral aneurism has ruptured. Surgery is one option in the treatment of SAH, if the hemorrhage is due to an injury or ruptured aneurysm. If no blood clot or aneurysm is identified then medical management is the way forward. For some with extensive damage death is likely and despite treatment cannot be avoided. Where medical management is possible, treatment may be as follows:
- Use of intravenous anti-hypertensives is preferable, as high blood pressure will undoubtedly exacerbate the problems and risks.
- Analgesia and anti-anxiety medications are also helpful to minimize pain and distress caused by the event.
- In many cases anti-seizure treatment such as ‘Phenytoin’ is given as patients can be at risk of seizures due to increased pressure in the brain.
- Bed rest to avoid exertion and subsequent pressure to the brain will be recommended.
- Avoidance of straining is also essential, and in most cases patients are given stool softeners and/or laxatives to assist bowel movements and avoid straining.
With treatment is ‘stroke’ prevention and therapy advancing all the time the outlook for those who suffer ischemic or subarachnoid episodes continues to improve. The key to all success where stroke is concerned is early diagnosis and subsequent treatment.