Stroke is an emergency condition that occurs when the blood flow to the brain stops, commonly called as brain attack. Blood supply to the brain can get affected due to blocking of arteries reaching the brain or due to bleeding in or around the brain. Thrombotic stroke occurs when an artery supplying blood to the brain gets blocked due to a clot, which can potentially cause damage to the brain.
Stroke is classified into three types based on the cause, which are, a blocked artery (ischemic stroke), bleeding in or around the brain (hemorrhagic stroke) and transient ischemic attack (a temporary episode).
Thrombotic stroke occurs from blockage of an artery supplying the neck or the brain. It is a type of ischemic stroke, as the disrupted blood supply can cause lack of oxygen and death of brain cells.
Ischemic stroke is of two types:
- Thrombotic Stroke - Blockage of arteries resulting from a clot within the arteries supplying the brain.
- Embolic Stroke - Blockage of arteries resulting from a clot elsewhere in the blood vessels of the body, which travel to the blood vessels in brain.
Transient ischemic attack (TIA) can also be a brief form of thrombotic stroke, in which temporary symptoms appear and is called a mini stroke. It too occurs when the clot formation is present in the arteries of the brain. The symptoms of TIA may be similar to stroke; may last for few minutes to hours but usually does not leave any permanent damage to the brain. It is considered as a warning sign of possible future stroke.
Types of Thrombotic Stroke
Thrombotic Stroke, which occurs due to blocking of arteries in the brain are also termed as cerebral thrombosis and it accounts for almost half of the cases of thrombotic stroke. Thrombotic stroke or cerebral thrombosis are divided into types, which are related to the place of the clot in the artery. These are:
- Large Vessel Thrombosis – Blockage occurs in the large arteries supplying the brain, like carotid artery or middle cerebral artery.
- Small Vessel Thrombosis or Lacunar Stroke – Blockage occurs in one or more smaller and deeply penetrating arteries of the brain. It is also called lacunar infarct, (lacunar means a cavity or hole) and is commonly seen in people with diabetes or high blood pressure.
Causes of Thrombotic Stroke
The brain is supplied by large and small arteries carrying pure blood. The brain receives nutrients and oxygen through the blood reaching through these arteries. These blood vessels can get blocked due to various reasons, however, the commonest cause of artery blockage is narrowing or arteries due to atherosclerosis.
Atherosclerosis is a condition, in which, cholesterol and other substances, in the form of plaque, get deposited on the inner walls of arteries. This narrows the passage through which blood can flow. When arteries become very narrow, clots can develop due to collection of blood cells in an area. These clots (thrombus) when formed, block the artery, thus cutting off the blood supply to the brain. The brain cells feel deficient in nutrition and oxygen resulting in stroke. Hence the term thrombotic stroke.
Other causes that can lead to formation of blood clots in the arteries of brain include, certain traumatic injuries causing clot formation in the brain, blood clotting disorders or due to use of certain drugs and substance abuse. Occasionally, certain types of headaches, or migraines can cause excessive spasm of an artery of the brain, resulting in clot formation.
Certain risk factors that may increase the chances of having a thrombotic stroke include, high cholesterol, high blood pressure, diabetes, obesity, smoking and a family history or a previous history of stroke.
Symptoms of Thrombotic Stroke
Thrombotic stroke usually presents itself in different ways, depending on the areas of the brain affected and the severity of disturbance in blood flow to the brain. Depending on the area affected, particular functions controlled by the brain can get damaged in varying degrees.
Symptoms of thrombotic stroke can include sudden appearance of:
- Headache, confusion or dizziness,
- Vision disturbances or sudden loss of vision,
- Weakness on one side of the body,
- Difficulty or inability to speak or slurred speech,
- Unstable walking, balancing problems and
- Co-ordination difficulty in hands and legs.
Treatment for Thrombotic Stroke
If the early signs of thrombotic stroke are sensed, immediate evaluation and treatment can be started, in which case, the chances of recovery are better. A thorough clinical examination, neurological assessment and related tests are done. Investigations like CT scan, Doppler ultrasound of the suspected arteries of brain and other tests as required are often performed.
Emergency treatment followed up with regular medications are required. Treatment includes medications to dissolve the clot and improve blood flow to the brain, which shows better results if given within 3 hours of beginning of symptoms. It is also necessary to treat underlying cause like high blood pressure or uncontrolled blood sugar in diabetes. In some cases, endovascular procedures in which the lodged thrombus or clot is removed through a surgical procedure, may be performed if appropriate.
Recovery Period for Thrombotic Stroke
Small thrombus that cause lack of blood supply for a short period and receiving timely treatment show better recovery. If blood supply is cut off for longer period, it can cause more damage. Depending on the symptoms and the damaged caused, rehabilitation may also be required.
Prognosis and recovery period depends on the size and location of the thrombus and severity and damage to the brain and other body parts.