Stroke falls under the category of cerebrovascular disease meaning disease involving the blood vessels of the central nervous system (brain, spinal cord and visual system). We all know someone that has had a stroke but many of us do not know what a stroke is. I have heard people refer to strokes when stating that a person’s blood pressure was too high or as an alternative name for a heart attack or to describe a simple fainting spell. I will use this post as a venue to describe the main types of strokes. Each subsequent post will go into more detail about the respective stroke subtypes. Before we go further, if you have hypertension it is critical that you get it under control and keep it under control.
This type of event probably doesn’t deserve its own category but because of how common it is, I will separate it. TIA is short for Transient Ischemic Attack. Many times it is referred to as a mini-stroke. The TIA is characteristic of neurologic dysfunction such as weakness, slurred speech or confusion that gets better on its own. Generally these symptoms are short lived lasting less than 24 hours. More specifically, there is no evidence of any permanent brain injury on specialized brain scans such as MRI.
This type of stroke occurs when there is insufficient blood flow to a portion of your brain. This can happen because an artery gets clogged similarly to what happens in a heart attack. A clot or large particle can be dislodged from elsewhere in the body that travels to the brain and blocks an artery. These clots usually originate from the heart, aorta or carotid artery. It is extremely unusual for strokes to be caused from clots from elsewhere in the body because they would have to travel through your lungs, which serve as a filter. Lastly, ischemic strokes can originate from hypoperfusion or insufficient blood flow not necessarily related to a total or near-total blockage of an artery. Hypoperfusion injury of your brain happens when your blood pressure is so low that not enough blood flows to the brain matter or if the oxygen levels in your blood fall to low. When I say that your blood pressure has to be very low I mean that it is VERY VERY low. If you are awake enough to complain that your blood pressure is too low then your blood pressure is not too low. This type of injury tends to happen following cardiac arrest, drowning or other drastic events.
The last subtype that will be included today are bleeding strokes. These bleeding strokes account for about 20% of the total number strokes annually. These strokes generally fall into one of two categories. The first is intracerebral hemorrhage (ICH) where there is bleeding directly into the brain. As the bleeding extends it damages the brain matter directly. It also increases the pressure within your skull, smashing the sensitive tissue against an unforgiving environment in the bones and dura. When the bleeding does not occur within the brain matter rather within the cerebrospinal fluid then it is classified as a subarachnoid hemorrhage.