The CVA (stroke) has various names, stroke being the most correct, but can also be called a cerebral infarction, cerebral ischemia, cerebral thrombosis. In this paper we discuss ischemic stroke and hemorrhagic stroke.
To understand the stroke you need to know four basic concepts:
Thrombus is a blood clot which is located inside the blood vessels, adhered to the wall thereof, blocking the passage of blood. The obstruction may be partial or total. When the vessel is obstructed by a thrombus, it is called thrombosis.
Piston is when a clot breaks free and travels through the bloodstream to get a pot with smaller size than the actual piston getting stuck and blocking the blood circulation. When a vessel is obstructed by an embolus, we face an emboli. A common example is pulmonary embolism.
Ischemia is the lack of blood supply to a tissue or organ. Every time the blood circulation is not sufficient for the functioning of cells, ischemia occurs. It is a reversible process if treated in time.
Infarct is a prolonged death of myocardial cell. It is generally caused by obstruction of the artery by a thrombus or a plunger. The best known is the infarction of the myocardium (heart muscle), but it can occur in any tissue or organ.
The stroke, however, is nothing more than a stroke of a region of the brain caused by a clot that forms in an artery or a cerebral embolus formed elsewhere in the body, which travels in the bloodstream to lodge in an artery of brain. There is also a hemorrhagic stroke which will be explained below.
Remember about the vascularization of the brain (blue vessels). When any of these vessels is impeded, ischemia occurs and hence a stroke.
The mechanism of cerebral thrombosis is the same as heart attack. The difference is that the first artery occurs in the brain and the other in a coronary artery.
People with high cholesterol deposit the same in their arteries to form plaques. It is upon these plates which develop thrombi. The thrombus grows quietly on top of cholesterol plaque and only causes symptoms when it becomes large enough to obstruct the passage of blood.
The stroke caused by an embolus usually originates in the heart, specifically in the left atrium. A cardiac arrhythmia called atrial fibrillation is the main cause of cerebral embolism. The atrium is fibrillating when not pulsing properly, therefore, the blood inside it stands, which favors coagulation and clot formation. Read about palpitations, tachycardia and cardiac arrhythmias to understand the concept of arrhythmia better.
In the photo below we can see the clot (or thrombus) (black dot) becoming an embolus from the heart to win the carotid artery and lodge in a cerebral artery, blocking the arrival of blood to a region of the brain.
Apart from thrombosis and embolism, there is a third type of cerebral infarction, which is caused by a cardiac arrest or a prolonged circulatory shock. This type of stroke is more serious, since lack of proper blood circulation causes ischemia throughout the brain, not just in the region as in case of a stroke caused by thrombus or embolus.
Prolonged cardiac arrest patients usually suffer irreversible brain damage. Three minutes of cardiac arrest, without medical attention, cause severe brain injuries. From the fifth minute chance of brain death is near 100%. Even when they start up quickly resuscitation (CPR) there is a time limit for survival of the brain. There are few cases that have been doing well after more than 10 minutes of resuscitation without response.
These three types of cerebral infarction are called ischemic stroke because the mechanism leading to an infarction is ischemia (insufficient blood perfusion), or by thrombus, embolus or circulatory shock.
The main risk factors for ischemic stroke (or just stroke) are:
Stroke is a framework that typically occurs in people over 50 years with risk factors listed above, but can occur in young people who have bleeding disorders or inflammatory diseases of the blood vessels, for example, antiphospholipid antibody, factor V Leiden, lupus or vasculitis.
In ischemic stroke, responsible for up to 85% of cases, there is a hemorrhagic stroke, caused by a ruptured blood vessel in the brain, which leads to intracranial bleeding. In general, hemorrhagic stroke occurs due to a weakness of the wall of a brain artery.
The main causes of hemorrhagic stroke are:
Trauma
Hypertension
Use of drugs that inhibit blood clotting such as heparin and warfarin
Smoking
Malformations of cerebral vessels
Vasculitis
Aneurysms in the brain
The hemorrhagic stroke is usually more dramatic than the ischemic stroke almost always reaching for a higher brain area.
The skull is a closed box which has no capacity to expand. When there is a major bleeding, blood leaks into the brain hematomas as they begin to compress it into the skull. This compression of the brain further contributes to neuronal injury and the risk of death.
There are two types of hemorrhagic stroke: intracerebral hemorrhage and subarachnoid hemorrhage. The first, as the name implies, occurs when the bleeding is located within the brain. Already a subarachnoid hemorrhage occurs when bleeding occurs between the brain and the meninges (membranes covering the brain).
The hemorrhagic stroke, mostly intraparenchymal (intracerebral), usually has a poor prognosis. The mortality rate is greater than 50% and only about 10% are without sequelae. When there are major bleedings and loss of consciousness, the mortality rate is 90%.
Now that you know the types of stroke, learn the most important part of it - the clinical picture.
Symptoms depend on the stroke area of the brain affected. The larger the area, in general, the more severe is the frame. Small infarcts in prime areas are also serious. The most common symptoms of stroke are:
Loss of balance and inability to stand up and difficulty performing simple tasks such as pushing a button, turn on the light or taking a glass or fork to mouth
The decreased sensitivity and / or tingling in a single part or just part of it is not usually a sign of stroke, but injuries to peripheral nerves or spine. Stroke often causes paralysis and decreased strength.
Tables of anxiety and hysteria may simulate a stroke, however, the majority of cases are easily distinguished by the doctor because the symptoms do not follow the logic of a neurological point of view. What the patient and his family can experience is hysteria with an expensive event with all strokes.
Causes of stroke
The stroke does not cause pain, except for an excruciating headache that may occur in cases of hemorrhagic stroke. Up to one third of strokes occur during sleep and the patient only notices amendment to wake up.
Hemorrhagic strokes in the table can develop very fast depending on its length and area of the brain affected. The patient complains of malaise and may progress rapidly to unconsciousness and cardiac arrest.
It is very common to present with a hypertensive stroke. The lack of blood in brain regions causes the body to increase blood pressure in a desperate enhance perfusion of blood to the brain. Do not try to control the pressure in these cases (especially if it is below 200/110 mmHg), as there is a danger of worsening cerebral ischemia if the pressure drops rapidly. If you suspect stroke, go to hospital immediately and allow doctors to control the pressure in the right way.
The transient ischemic attack, known as TIA, occurs when the symptoms disappear with the stroke less than 24 hours after its onset. The TIA is an incomplete stroke, which occurs when ischemia can be reversed before it occurs spontaneously as infarction of the affected region.
Who had a TIA presents a high risk of suffering a stroke in the future and should be under a close control of a neurologist.
There is a class of medications called thrombolytics, which dissolve thrombi and emboli and restores the cerebral circulation, removing and preventing ischemia infarction. However, it only takes effect within 3 hours of stroke, and even more effective if administered within the first hour and a half.
Note: recent scientific studies have shown benefits of thrombolytics to 4.5 hours after symptom onset.
At the first sign of stroke patients should be taken immediately to an emergency in order to have time to control the cerebral ischemia.
Therefore, the worst thing you can do when there are symptoms of stroke is waiting to see if the picture will improve by itself. If there is a suspicion of stroke during the night it should not be expected till dawn to take the patient to hospital. If there is no car available, call an ambulance immediately.
Do not treat yourself and not wait to see if the symptoms will disappear. If you have questions about the exact time of symptom onset, transport the patient to an emergency room and let the doctors assess whether or not to indicate thrombolytic therapy. Never let the patient with suspected stroke drive the car. The framework can evolve and a serious accident can occur.
Thrombolytic agents are only indicated in case of ischemic stroke. Thrombolytic agents are not indicated for hemorrhagic stroke. The differential diagnosis between these two types of stroke is done by computed tomography of the brain.
In hemorrhagic stroke emergency surgery may be required if the brain is being compressed by the bleeding. Treatment consists of surgical removal of the clot / hematoma and part of the skull so the brain can expand without being compressed.
