According to the World Health Organisation, a Stroke is defined,as "an accident to the brain with rapidly developing clinical signs of focal or global disturbance to brain function, with symptoms lasting 24 hours or longer, or leading to death with no apparent cause other than of vascular origin and includes cerebral infarction, intracerebral hemorrhage, and subarachnoid hemorrhage".
What happens in a stroke?
A stroke occurs when there is an interruption of the blood supply to a particular area of the brain, ultimately leading to cell injury and cell death.
Strokes can be classified in two ways:
Ischemic strokes
Haemorrhagic strokes
Ischaemic Strokes
Ischaemic strokes are the most common, accounting for up to 80% of strokes, and occur when there is an occlusion of a blood vessel impairing the flow of blood to the brain.
There are few types of strokes(Ischaemic Strokes)according to the cause.
Thrombotic - Where a blood clot forms in a main brain artery or within the small blood vessels deep inside the brain. The clot usually forms around atherosclerotic plaques.
Embolic - A blood clot, air bubble or fat globule forms within a blood vessel elsewhere in the body and is carried to the brain.
Systemic Hypoperfusion - A general decrease in blood supply, (in shock) caused by chronic, uncontrolled hypertension resulting in the pathological entity of lipohyalinosis and arteriolosclerosis.
Venous Thrombosis
Haemorrhagic Strokes
Haemorrhagic Strokes occur when a blood vessel in the brain ruptures and bleeds.
Intracerebral Haemorrhagic Stroke — there is bleeding from a blood vessel within the brain. High blood pressure is the main cause of intracerebral haemorrhagic stroke.
Subarachnoid Haemorrhagic Stroke — there is bleeding from a blood vessel between the surface of the brain and the arachnoid tissues that cover the brain.
Causes for stroke
Many causes can lead to a stroke. Some of the most common risk factors include,
Hypertension
Diabetes mellitus
Hypercholesterolemia
Physical inactivity,
Obesity,
Genetics
Smoking.
How to identify the features of a stroke?
Sudden numbness or weakness in the face, arm, or leg, especially on one side of the body.
Sudden confusion, trouble speaking, or difficulty understanding speech.
Sudden trouble seeing in one or both eyes.
Sudden trouble in walking, dizziness, loss of balance, or lack of coordination.
M.D. Ranathunga
References
Tadi P, Lui F. Acute Stroke (Cerebrovascular Accident) [Updated 2020 Jul 6]. In: StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing; 2020 Jan-.
Global Burden of Stroke. The Atlas of Heart Disease and Stroke. MacKay J, Mensah GA. World Health Organization.
Townsend N, Wickramasinghe K, Bhatnagar P, Smolina K, Nichols M, Leal J, Luengo-Fernandez R, Rayner M (2012). Coronary heart disease statistics 2012 edition. British Heart Foundation: London. P21
Zafar F, Tariq W, Shoaib RF, Shah A, Siddique M, Zaki A, Assad S. Frequency of ischemic stroke subtypes based on toast classification at a tertiary care center in Pakistan. Asian journal of neurosurgery. 2018 Oct;13(4):984.
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