Stroke, also called cerebrovascular accident or brain attack, is a sudden impairment of cerebral circulation in one or more of the blood vessels supplying the brain. Strokes interrupt the oxygen supply to the brain tissues and can cause serious damage. For anyone who has suffered a stroke, it is vitally important to restore normal circulation as soon as possible to limit damage to the brain tissues.Although mortality from strokes has been significantly reduced from around 90% in the 1950s, the number still hovers around the 30% and stroke could soon be the most common cause of death worldwide. Of those who do survive, about half remain permanently disabled and many experience a recurrence within weeks, months or years.
Causes and Incidence
A stroke results from obstruction of a blood vessel, typically outside the brain, but occasionally within the brain itself. Factors that increase the risk of stroke include a history of transient ischemic attacks, atherosclerosis, hypertension, kidney disease, arrhythmias (particularly atrial fibrillation), rheumatic heart disease, diabetes, postural hypertension, heart enlargement, high serum cholesterol, smoking, lack of exercise, long time use of contraceptives, obesity and a family history of strokes. Females have additional risk factors for stroke such as oral contraceptives that are not present in men. Cocaine induced ischemic stroke is now being reported in younger patients.The incidence of stroke increases exponentially from 30 years of age, and etiology varies by age, 95% of strokes occur in people age 45 and older, and two thirds of strokes occur in those over the age of 65. Men traditionally have had a greater risk of stroke than women but women start catching up to men five or 10 years after menopause. While stroke is most common in the elderly, people of any age and any level of physical fitness can suffer the injury. A persons risk of dying if he or she does have a stroke also increases with age.Stroke is uncommon in children accounting for only a small percentage of stroke cases each year. Stroke in children is often secondary to congenital heart disease, abnormalities of intracranial vessels genetic disorders and blood disorders such as thrombophilia.
Types of Stroke
Strokes can be classified into two major categories: ischemic and hemorrhagic, 80% of strokes are due to ischemia, the rest are due to hemorrhage.
The major causes of stroke are thrombosis, embolism and hemorrhage:
- Thrombosis is the most common cause in middle age and elderly people as they tend to have a higher incidence of arterial plague, diabetes or hypertension. It can occur at any age, especially in those with a history of rheumatic heart disease, endocarditis, cardiac arrhythmias, or after open heart surgery.
- Embolism is the second most common cause of stroke. Embolisms occur when a blood vessel is blocked by a clot, a tumor, fat, bacteria or air. Embolisms usually develop within 10 to 20 seconds and without warning and when they reach the brain, will cut off circulation by lodging in a narrow part of an artery causing swelling and tissue death.
- Hemorrhage the third most common type of stroke, which is more prevalent in women than men, like embolism can occur suddenly at any age. It results from chronic hypertension or from aneurysms that cause a sudden rupture of a cerebral artery.
Signs and Symptoms of Stroke
Stroke commonly presents with loss of sensory and motor function on one side of the body (85% of ischemic stroke patients have hemiparesis), change in vision, gait, or ability to speak or understand or sudden, severe headache.Clinical features of stroke vary according to; the blood vessel affected and the part of the brain that vessel supplies, the severity of damage and the ability of the affected area to compensate for decreased blood supply by means of collateral circulation. Strokes on the left side of the brain primarily affect the right half of the body, and vice versa. Most forms of stroke are not associated with headache, apart from subarachnoid hemorrhage and cerebral venous thrombosis and occasionally intracerebral hemorrhage.
Symptoms are usually classified according to the blood vessel affected;
- Middle cerebral artery: difficulty swallowing, difficulty speaking, visual field reduction and paralysis of one side, particularly in the face and arm.
- Carotid artery: weakness, paralysis, numbness, visual disturbances, headaches, altered levels of consciousness, difficulty speaking and a drooping eyelid.
- Vertebrobasilar artery: weakness, numbness around the lips, visual field cuts, double vision, poor coordination, difficulty swallowing, slurred speech, dizziness and amnesia.
- Anterior cerebral artery: confusion, weakness and numbness (especially in the leg), incontinence, loss of coordination, impaired motor and sensory functions and personality changes.
- Posterior cerebral artery: sensory impairment, visual field reduction, dyslexia, coma, cortical blindness, but not paralysis.
Diagnosis
For people referred to the emergency room, early recognition of stroke is deemed important as this can expedite diagnostic tests and treatments. Strokes due to thrombosis embolism, or arterial spasm, which cause ischemia, must be distinguished from those due to hemorrhage, which are usually severe and often fatal. Stroke is diagnosed through several techniques: observation of clinical features, a neurological examination, CT scans or MRI scans, Doppler ultrasound, and arteriography.
Treatment
Surgery to improve cerebral circulation, tissue plasminogen activator (tPA) for clot dissolution, anti coagulants and anticonvulsants are commonly used to treat stroke. Treatment to break up a blood clot, the major cause of stroke, must begin within three hours of the stroke to be effective. tPA must be administered within three hours of the stroke event. Therefore, patients who awaken with stroke symptoms are ineligible for tPA therapy, as the time of onset cannot be accurately determined. Patients with clot-related (thrombotic or embolic) stroke who are ineligible for tPA treatment may be treated with heparin or other blood thinners, or with aspirin or other anti-clotting agents in some cases.Among patients with nonvalvular atrial fibrillation, anticoagulation can reduce stroke by 60% while antiplatelet agents can reduce stroke by 20%. Anticoagulants and antithrombotics, keys in treating ischemic stroke, can make bleeding worse and cannot be used in intracerebral hemorrhage. In addition to definitive therapies, management of acute stroke includes control of blood sugars, ensuring the patient has adequate oxygenation and adequate intravenous fluids. Analgesics, stool softeners to prevent straining and corticosteroids to minimize associated edema may also be used. There are anecdotal reports of the use of a new, non transdermal acupuncture patch to reduce post stroke complications.
Prevention
Generally there are three treatment stages for stroke: prevention, therapy immediately after the stroke, and post stroke rehabilitation. Therapies to prevent a first or recurrent stroke are based on treating an individuals underlying risk factors for stroke, such as hypertension, atrial fibrillation, and diabetes. Lowering blood pressure has been conclusively shown to prevent both ischemic and hemorrhagic strokes. Aspirin prevents against first stroke in patients who have suffered a myocardial infarction. Nutrition, specifically the Mediterranean-style diet, has the potential of more than halving stroke risk. Acute stroke therapies try to stop a stroke while it is happening by quickly dissolving the blood clot causing an ischemic stroke or by stopping the bleeding of a hemorrhagic stroke. Post stroke rehabilitation helps individuals overcome disabilities that result from stroke damage. The most popular classes of drugs used to prevent or treat stroke are antithrombotics (antiplatelet agents and anticoagulants) and thrombolytics.
Rehabilitation
Stroke may cause problems with thinking, awareness, attention, learning, judgment, and memory. Survivors often have problems understanding or forming speech, they may have difficulty controlling their emotions or may express inappropriate emotions. They may also have numbness or strange sensations
Stroke rehabilitation is the process by which patients with disabling strokes undergo treatment to help them return to normal life as much as possible by regaining and relearning the skills of everyday living. New advances in imaging and rehabilitation have shown that the brain can compensate for function lost as a result of stroke, therefore stroke rehabilitation should be started as soon as possible. After a stroke, both the stroke survivor and the family are often frightened about being at home again and getting used to life after stroke. A stroke survivor has to get used to doing things differently and it can impact on intimacy, relationships and on work and hobbies, so for most stroke patients, physical therapy and occupational therapy are the cornerstones of the rehabilitation process. Since 30 to 50% of stroke survivors suffer post stroke depression, which is characterized by lethargy, irritability, sleep disturbances, lowered self esteem, and withdrawal, some stroke management teams may also include psychologists, social workers, and pharmacists since at least one third of the patients manifest post stroke depression.
