What is a stroke and how is it treated?Sunday, March 28, 2021
STROKES or cerebrovascular accidents result in significant mortality and morbidity. When combined with cardiac diseases, these two entities are the most common cause of death in Jamaica and indeed worldwide.
Not only are strokes an important cause of death but they also result in life-changing circumstances for many people such as the loss of speech and limb movement, the inability to live independently and the loss of ability to work. The prevention, recognition and treatment of strokes are thus an important part of health as we get older. Much like with heart disease, decades of research have yielded much information which has improved prevention and treatment of the patient presenting with stroke.
What is a stroke?
A stroke can simply be thought of as the sudden death of tissue in the brain, most often because of an abrupt loss of blood flow. Strokes are divided into two categories based on the mechanism. These two categories are ischaemic strokes and haemorrhagic strokes. Ischaemic strokes result from the sudden occlusion of a blood vessel. The method of this occlusion can again be subdivided into two. The first type of occlusion occurs at the level of the blood vessel within the brain itself, so-called thrombotic ischemic strokes, eg, cholesterol can be laid down in the wall of the artery and can cause a sudden occlusion. In the second scenario the blood vessels in the brain can be relatively normal but material can arrive from other areas of the body via the blood stream and occlude the vessel – this is termed an embolic stroke. Haemorrhagic strokes result from abnormalities in the blood vessels in the brain that make them prone to leaking into brain tissue and thus causing death and damage to the surrounding cells.
What are the causes of a stroke?
Ischaemic strokes usually constitute more than 80 per cent of strokes overall with haemorrhagic strokes occurring in less than 20 per cent of patients. Thrombotic ischaemic strokes are caused by sudden clotting in the blood vessel. This clotting is usually the result of abnormalities in the blood vessel wall, most commonly from cholesterol deposition or atherosclerosis. There can be other causes of abnormalities in the vessel wall that are less common including inflammation (vasculitis) which can be a result of auto-immune disease such as lupus, or abnormalities of the clotting mechanisms of the body. The same disease processes that we have previously discussed in terms of cholesterol deposition in the heart arteries are important in the blood vessels of the brain. Therefore, hypertension, diabetes, elevated blood cholesterol, smoking, age, family history are important factors that can lead to clotting in the brain arteries.
Embolic ischaemic strokes result from material travelling through the blood stream ending up in the small vessels of the brain and occluding them. This embolic material may be cholesterol debris from large arteries that are closer to the heart such as the vessels of the neck or the large vessels in the chest. Some cardiac conditions can result in clots forming in the heart which can travel via the blood stream and end up in the vessels of the brain. This can be seen in atrial fibrillation (a type of irregular heart rhythm) or less frequently after some heart attacks when clotting can take place on the inside wall of the heart. Other kinds of debris can less commonly leave the heart and get up to the brain. This includes infected material if there is an infection of the heart valves, or material from tumors or masses in the heart.
Haemorrhagic strokes result from bleeding from blood vessels into brain tissue and are much less common than ischaemic strokes. There usually is some factor that has caused the wall of the blood vessel to weaken. The most common factor is that of chronic, poorly controlled high blood pressure. Hypertension is thus an important risk factor for both ischaemic and haemorrhagic stroke.
Other factors can include infiltration of abnormal material into the wall of the blood vessel which can be seen in a condition known as amyloidosis, inflammation of the blood vessel wall and various congenital abnormalities. These abnormalities can include abnormalities of the tissue of the blood vessel wall, making it more likely to expand and rupture over time.
What are the symptoms of a stroke?
As noted above, a stroke is simply the sudden death of brain tissue and the symptoms that occur are going to be related to the area of the brain that has suffered damage. Strokes commonly impact the areas that control movement, speech, and sensation. The symptoms of a stroke tend to affect one side of the body as each half of the brain is responsible for the contralateral half of the body, ie, the left side of the brain controls the right half of the body and vice versa. Patients often present with the sudden inability to move the side of the body affected. This can involve both the arm and leg or, depending on the size and specific location of the stroke, the entire half of the body may not be affected.
A stroke can also affect the facial muscles, that is “twisting of the face”, resulting in the inability to move the eyelids or to smile. The area of the brain that controls speech production is also commonly affected. This can result in difficulty speaking and can be complete, with the patient being unable to speak, or less extensive with the patient producing incoherent or garbled speech. Strokes can also involve language processing so that speech output can be preserved but the patient is unable to comprehend. Sensation is commonly affected, with strokes and patients perhaps unable to feel a touch, painful sensations, or temperature changes. Less common manifestations of strokes may include severe headache, loss of vision, imbalance, difficulty walking, problems with coordination of movement and emotional changes.
How can I quickly recognise a potential stroke at home?
When a patient is experiencing symptoms that may be stroke relat it is important to seek emergency medical attention as quickly as is possible. The American Heart Association has suggested the use of the acronym FAST to aid lay people in quickly assessing the likelihood of stroke symptoms. The F is for face – is there drooping or numbness of one side of the patient's face? The patient can be asked to smile to better evaluate any abnormalities. The A is for arm – is the arm numb or weak? Can the patient lift the arm? The S is for speech – is the speech slurred? Is the patient difficult to understand? Unable to speak? Can s/he repeat a simple sentence? The T is for time. If any of the symptoms are present it is time to seek emergency care for the patient.
In future articles we will look further at stroke diagnosis, treatment, and prevention.
Dr Ernest Madu, MD, FACC; and Dr Paul Edwards, MD, FACC are consultant cardiologists at Heart Institute of the Caribbean (HIC) and HIC Heart Hospital.
Dr Madu is a main TED Speaker whose TED talk has been translated into 19 languages, seen, and shared by more than 500,000 viewers. He has received the Distinguished Cardiologist Award, the highest award from the American College of Cardiology, and has been named among the 100 most influential people in health care and among the 30 most influential in public health. Dr Madu is also a recipient of the Global Health Champion Award from the University of Pennsylvania. Dr Madu was past CEO of HIC and is currently the chairman of IHS Holdings Ltd, an asset management company with interests in the USA, Africa, and the Caribbean.
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