Types of Strokes

November 14 11:09 2017 Print This Article

Overview

Stroke is an umbrella term for a set of conditions that are all characterized by loss of blood-flow to the brain. There are clear, recognizable signs and symptoms of a stroke, which are known by the acronym ‘FAST’. Stroke is a generic term and there are actually 5 different types of strokes. In this article, we will learn more about them.

Introduction

The human brain is the main component of the Central Nervous System and hence one of the most important organs in the body. Although it’s just 2% of the total body-weight (for example – 1.6 kgs in a person who weighs 80 kg), it requires as much as 15-20% of the total blood supply, for proper functioning. The brain stem is a pipeline at the base of the brain which acts as a conduit for arteries and veins leading in and out of the brain. The brain receives blood from the heart through 2 sources: the carotid circuit consisting of internal carotid arteries, and another circuit made of vertebral arteries which converge at a point on the brain stem.

Any blockage, or any disruption to blood-flow, anywhere in this supply network, can affect blood-supply to the brain. Tissues that are no longer served the necessary blood start dying out. As a result, functionalities provided by those tissues no longer work. This condition can be temporary or permanent and is called a ‘brain stroke’, or just stroke.

Signs and symptoms of stroke

Stroke can be a serious condition that can cause life-threatening conditions or permanent disability. A patient who has just suffered a stroke must be rushed immediately to the hospital in the golden hour, so that effects of the condition can be reversed. To do so, one must be able to recognize the signs and symptoms of stroke. These signs are known by the acronym FAST.

• F – face dropping: the face is dropping on one side and has a numbness. If asked to smile, the person may smile but it appears crooked.
• A – Arms weakening: One of the 2 arms may have gone numb or become very weak. If asked to raise both arms, the person may only be able to raise one of them.
• S – Speech: the person struggles to speech, or the speech is slurred, or both
• T – Time: time to rush the person to a hospital for emergency treatment

Types of strokes

There are 5 different types of strokes with their own unique cause, risk factors, unique symptoms and risk of complications. However, FAST is relevant in all of these types.

Ischemic Stroke

• In medical terms, ‘Ischemic’ means a particular organ or tissue is not getting adequate blood supply and hence oxygen, due to one or more reasons. So, an Ischemic stroke means, the brain is not getting its full supply of blood. This happens due to a blood-clot in either one of the main arteries that supply blood from the heart to the brain. Or the blood-clot develops in one of the smaller arteries inside the brain.
• In both cases, the cause is atherosclerosis, and hence this type of ischemic stroke is called atherosclerotic stroke. In earlier articles, we have discussed what is atherosclerosis. Sometimes, a clot may develop in another part of the body and travel through the blood-vessels to a supply artery or an internal artery in the brain. Such a type of ischemic stroke is called embolic stroke.
• Risk Factors for Ischemic stroke include atrial fibrillation, blood-clotting disorders, myocardial infarction (heart attack), trauma or injury to blood-vessels in the neck, a disorder in one of the valves of the heart, smoking, older age, irregular heartbeat (arrhythmias), high cholesterol, high blood-pressure, heart disease and a family history of stroke.
• Other than FAS, symptoms include dizziness, confusion, lack of balance or coordination, double vision and vision loss.
• If left untreated, complications include permanent weakness or numbness in one part of the body, cognitive issues (problems with memory and understanding), and frequent seizures.

Transient Ischemic Stroke (TIA)

• Transient ischemic stroke is very similar to ischemic stroke except that in this case, the condition is temporary and can resolve in 24-hours’ time, on its own, without any intervention. That is why it’s called a mini-stroke. So, what this means is that, the blood-clot which caused the disruption got dislodged after some time and moved away, thereby restoring blood to the tissues served by that/those artery/arteries.
• Causes, risk factors and symptoms are all similar to Ischemic stroke.

Haemorrhagic Stroke

• In medical terms, haemorrhage refers to a rupture in one or more blood-vessels leading to leakage of blood. So as the name implies, in a haemorrhagic stroke, a blood-vessel supplying blood to brain tissues has developed a haemorrhage and is leaking blood in and around the brain. This again is of 2 types:
• Sub-arachnoid: In this case, the haemorrhage has happened in the space between the brain and the skull. Blood leaks in to this space, and when combined with the cerebrospinal fluid, there is more liquid now that begins to compress or squeeze the brain (given that the skull is hard and cannot expand).
• Inter-cerebral: In this case, the rupture of blood-vessels leads to blood leaking into the tissues inside the brain. The tissues served by the ruptured blood-vessel no longer get enough blood, causing a stroke.
• There are several risk-factors for haemorrhagic stroke and these include: age over 65 years, an unhealthy diet rich in sugars and fats, currently suffering from diabetes, hypertension or high cholesterol, being overweight, a personal or family history of strokes, smoking, sedentary lifestyle, trauma or injuries in the recent past, blood-clotting disorders, use of recreational drugs, a genetic condition called AVM which is marked by abnormal blood-vessels, and aneurysm (balloon-like bulges in blood-vessels which get filled with blood and then burst).
• Other than FAS, symptoms include headaches, nausea, vomiting, light sensitivity, vision problems and syncope (fainting).
• Complications from untreated haemorrhagic stroke include those mentioned under ischemic stroke. Additionally – heart trouble, difficulty in swallowing, eating and drinking.

Brain-stem stroke

• In this case, there is a disruption in the blood-supply in arteries, at the brain stem precisely. Unlike the earlier types of strokes which generally affect one side of the body, in this case, both sides are affected. This makes it even more serious.
• The cause for the disruption in blood-supply may be a blood-clot (ischemic), haemorhages (haemorrhagic) or trauma (injury to blood-vessels due to sudden, violent movements of the head or neck).
• Risk factors include atrial fibrillation, heart disease, hypertension, diabetes and smoking.
• Symptoms may not be visible immediately and may take some time to show up. One has to be watchful of the same, and they include:
  • Lack of balance, coordination and vertigo
  • Dizziness and syncope (fainting)
  • Nausea and/or vomiting
  • Vision problems
  • Difficulty in speaking or swallowing
  • Hypertension and difficulty in breathing
  • “Locked in” syndrome: the person’s body below the neck is frozen and cannot move. He/she can only move the eyes.

Cryptogenic stroke

• Also called Stroke of unknown cause, as the cause of this type is not clearly known. One of the suspects is ischemic stroke that happens deep inside the brain, however, there is not enough data for this.
• Risk Factors include:
  • Atrial fibrillation– a type of irregular heartbeat
  • Problems in structure of the heart (example – patent foramen ovale)
  • Atherosclerosis and hardening of the large arteries
  • Blood clotting disorders such as thrombophilia
• Symptoms include chest pain (angina), dizziness and irregular heartbeat (arrhythmias).

Kauvery Hospital is globally known for its multidisciplinary services at all its Centers of Excellence, and for its comprehensive, Avant-Grade technology, especially in diagnostics and remedial care in heart diseases, transplantation, vascular and neurosciences medicine. Located in the heart of Trichy (Tennur, Royal Road and Alexandria Road (Cantonment), Chennai, Hosur, Salem, Tirunelveli and Bengaluru, the hospital also renders adult and pediatric trauma care.

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Updated on 2^nd Feb 2024