Wednesday, 8 June 2016

Wessam Bou-Assaly - The Different Types of Strokes

A stroke can occur in different parts of the brain, and each type of stroke affects the brain in a different way. Wessam Bou-Assaly is a radiologist who studied neuroradiology as well as nuclear medicine. Both of these sub disciplines can be used to study, diagnose, and treat the brain. Neuroradiology can be used to identify the signs of a stroke. It is important to know about the different types of strokes, and their causes.

There are mainly three types of strokes :

  • ischemic stroke (caused by blood clots)
  • hemorrhagic stroke (caused by ruptured blood vessels that cause brain bleeding)
  • transient ischemic attack (TIA) (a “mini-stroke,” caused by a temporary blood clot)

  • Ischemic Stroke
    About 80 percent of strokes are ischemic. An ischemic stroke is most frequently caused by a blood clot that lodges in an artery and blocks the flow of blood to a part of the brain. High blood pressure and atherosclerotic disease are the most important risk factor for ischemic stroke.

    Ischemic strokes are typically preceded by symptoms or warning signs that may include loss of strength or sensation on one side of the body, problems with speech and language or changes in vision or balance.  They usually occur at night or first thing in the morning. Symptoms develop over a few minutes or worsen over hours.

    Often a TIA (transient ischemic attack) [see below] or “mini-stroke” may offer some warning of a major ischemic stroke.

    There are three types of ISCHEMIC strokes:
    • Thrombotic strokes are caused by a blood clot (thrombus) in an artery going to the brain.  
    • Embolic strokes occur when a clot that’s formed elsewhere (usually in the heart or neck arteries, such as carotid artery ) travels in the blood stream and clogs a blood vessel in or leading to the brain.
    • Systemic hypoperfusion (low blood flow) is caused by circulatory failure of the heart.
    Hemorrhagic Stroke
    A hemorrhagic stroke occurs when a blood vessel ruptures within the brain. About 15 to 20 percent of strokes are hemorrhagic. There are two kinds of stroke due to ruptured blood vessels:  subarachnoid hemorrhage due to ruptured aneurysms and intracerebral hemorrhage due to ruptured blood vessels.   In both types of hemorrhagic stroke, blood flow is disrupted to part of the brain.
    • Subarachnoid hemorrhage most commonly occurs when an aneurysm ruptures and bleeds into the space between the brain and the skull. Most aneurysms are congenital and rupture due to high blood pressure.  
    • Intracerebral hemorrhage occurs when a blood vessel bleeds into the tissue deep within the brain.  The main causes are chronically high blood pressure and aging blood vessels. Arteriovenous Malformations (AVMs) are also congenital malformations of blood vessels in the brain which can rupture into brain tissue as they get larger.
    Victims of hemorrhagic strokes are often younger and the fatality rate is higher than for ischemic stroke.  Overall prognosis is also poorer for those who have hemorrhagic strokes. The symptoms of a hemorrhagic stroke usually appear suddenly and often include:
    • very severe headache
    • nausea and vomiting.
    • partial or total loss of consciousness 

    Wessam Bou-Assaly is an experienced radiologist in the neuroradiology subfield.