Neurological Health

Understanding Stroke

Written by
Dr. Saumya Mittal
and medically reviewed by iCliniq medical review team.

Published on Aug 08, 2014 and last reviewed on Jul 22, 2019   -  3 min read

Abstract

Abstract

Where you aware that a stroke is also called a brain attack? To understand the pathophysiology and types of stroke, read the article.

Understanding Stroke

Stroke, something that most people realize by its most common symptom - paralysis, is one of the most common syndromes affecting the elderly and not so infrequently, even the youngsters.

One of the most common questions I face when I tell my patient that he/she has had a stroke is - “What does that mean? What has happened inside the body?” The idea of these next few words is to tell you what happens inside the body when a stroke occurs.

Brain Attack and Heart Attack

  • Stroke -- to make it more easily understood, may be called “brain” attack (drawing on the meaning and panic that is understood by the masses when someone utters the term “heart” attack). The meaning is not exactly very different.
  • Heart attack appears when the blood vessels supplying the heart are affected and the blood flowing through them is insufficient to maintain the survival of the heart.
  • Similarly, ‘“brain” attack occurs when the blood supply to the brain is affected and the circulation and blood supply to the heart falls beyond what is needed for brain’s survival.

How Does Brain Attack Happen?

Having understood something about how and why “brain attack” happens, one may proceed to know how the blood vessel is affected. There are few basic ways in which the blood vessel is affected:

  • One is that the flow of blood is stopped by a plug inside the artery. This plug may have formed in the vessel, like a thrombus (A blood clot).
  • Alternatively, some kind of particle may flow in from another part of the body and come to get stuck in the vessel (also known as emboli).
  • Sometimes, fat may accumulate in the vessel and gradually reduce the lumen of the vessel till very minimum blood can flow through it (atherosclerosis).
  • Again, alternatively, the vessel walls may contract thereby reducing the flow of blood through it (stenosis).
  • Finally, the vessel may have ruptured causing a cerebral haemorrhage, thereby causing a stroke.

If I try to explain this further, consider a water pipe through which water is flowing. If the water freezes at a certain point and the ice formed stops the flow of water, this may be understood as thrombus.

If there is some trash on the pipe and it comes to another point and gets stuck at another point away from where it has entered the pipe in the first place, the blood flow reduces. This may be understood as emboli.

When hard water flows through a pipe, salt always deposits on the wall of the pipe. When the wall is sufficiently coated with these minerals, obstruction may occur due to narrow lumen and you tend to get a reduced flow of water through the pipe. This may explain to you the phenomenon of atherosclerosis.

Stenosis may be understood if one considers a pipe that is thinner at one of the points in its course, thereby allowing only a limited flow of water through your tap.

When a pipe bursts, the water is lost and again nothing comes through the tap. That’s haemorrhage.

Ischemic Stroke, Transient Ischemic Stroke and Cerebral Haemorrhage

The first four mechanisms cause a reduced supply of oxygen to the brain and are therefore called ischemic stroke. The final mechanism is of course known as cerebral haemorrhage.

Amongst ischemic stroke, the duration of symptoms leads to another classification. If the symptoms occur for a very short duration, like 15 minutes to a day, and thereafter a full recovery of symptoms is noted, the episode is known as transient ischemic attack. It is usually a less well known warning sign that should make the patient aware that something is wrong and that evaluation is in order. The duration is short because the incident is short lived and the blood supply and therefore the oxygen supply to the brain is restored before any damage can happen (remember brain cells cannot regenerate).

Alternatively if the symptoms last longer than 24 hours or if the neuroradioimaging (CT scan or MRI of the head) shows any changes, it is likely that the damage has happened to the brain tissue. And this condition is known as the infarction of the brain.

Finally, the vessel may have ruptured causing a cerebral haemorrhage, thereby causing a stroke. This usually happens when the blood vessel is weak at some point, if the pressure is too high on the vessels or if the patient is prone to bleeding (naturally or due to medicines for another conditions e.g. warfarin).

Consult a neurologist online --> https://www.icliniq.com/ask-a-doctor-online/neurologist if you would like to ask more about stroke.

Last reviewed at:
22 Jul 2019  -  3 min read

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