Cerebrovascular accident (CVA) is a medical condition that occurs when blood flow to a part of the brain stops. This is a very worrying pathology, as it is estimated that 17 million people worldwide suffer from stroke. 17 million people worldwide suffer a stroke each year.. This translates, depending on the region studied, into about 14 cases per 100,000 inhabitants or, if you prefer, one in six people will suffer a stroke in their lifetime.
The world of stroke is complex both terminologically and in terms of classification. For example, first of all we should point out that stroke, ictus, cerebral infarction, stroke, apoplexy and cerebrovascular attack are all synonyms: medically, we are talking about the same thing even if we change the words.
Once we have briefly addressed the situation of strokes at a global level and the terminological conglomerate that defines them, it is normal to ask the following question: what types are there? If this doubt has assailed you while reading the introductory lines, don’t worry. Here we bring you the 6 types of stroke and their characteristics.
What is a stroke?
As we have said before, a stroke or cerebrovascular accident (CVA) occurs when the blood supply to a part of the brain is interrupted or reduced, which prevents the brain tissue from receiving oxygen and nutrients.. Due to this lack of blood flow, the cells of the affected tissue begin to die within minutes.
Several studies show truly worrying data regarding this pathology. For example, it is estimated that in Chile in 2016 there were almost 8,500 deaths due to strokes, which translates to 15% of deaths and causes of disability combined throughout the country.
In addition to all this, it is worth noting that approximately 30% of stroke survivors present significant disability to perform daily tasks and that, in addition, 10% of them end up developing dementia in the 3 months following the accident. As you can see, the stroke itself is only the beginning of the journey.
What are the types of stroke?
The epidemiological data are clear and concise, because the numbers do not lie. Unfortunately, words are subject to personal interpretation and, therefore, we are now entering into a somewhat difficult terrain. We are going to describe the types of stroke according to professional portals, such as the Mayo Clinic and the National Library of Medicine of the United States.
Even so, we must point out that the classification criteria vary significantly according to the sources consulted. The consensus is clear at the baseline level: there are two main types of stroke, ischemic and hemorrhagic.. It is in the ramifications of each that things get a bit more complicated. Without further ado, let’s get down to it.
1. Ischemic stroke
An ischemic stroke is the one that happens happens when an artery is obstructedusually by a blood clot or thrombus. This “blockage” partially or totally limits blood flow, reducing the amount of oxygen reaching the brain. It is the most common type of stroke, accounting for 80-85% of cases. In countries such as Spain, it is reported to occur in 150-200 cases per 100,000 inhabitants, generally in adults or the elderly. Below, we present each of its variants.
1.1 Ischemic stroke of vascular and hemodynamic origin
It is characterized by arterial stenosis (vasoconstriction) reactive to a multitude of processes. Normally is due to a decrease in cardiac output, i.e., blood volumei.e. the volume of blood expelled by one ventricle of the heart in one minute or, alternatively, due to severe and sustained arterial tension.
1.2 Intravascular origin: thrombotic or atherothrombotic stroke
We are dealing with phenomena of atherosclerosis, ie, clogging of the arteries by lipids, cholesterol and other substances.. The thrombotic phenomenon occurs when a clot forms in a normal artery, whereas atherothrombosis occurs when the clot forms in a pre-existing damaged area.
Risk factors for thrombotic and atherothrombotic strokes include obesity, hypertension, diabetes or increased blood cholesterol. For various reasons, clots tend to occur more often in some arteries than in others. For example, the origin in the internal carotid arteries, which are essential for cerebral irrigation, is particularly frequent.
1.3 Embolic stroke
We are also talking about a clot, but in this case it forms in another part of the body, usually in the veins of the brain.usually in the veins of the upper chest and neck or in the heart. This plug or embolus breaks away from the site of origin and, after traveling through the bloodstream, ends up plugging a blood vessel of smaller diameter than at the site of origin.
The embolus is usually a blood clot that forms in the heart, but it can also be a fracture, a tumor, a drug or even an air bubble. In fact, anything that impedes blood flow originating in a location other than the one it is blocking can be considered an embolus.
1.4 Lacunar stroke
This variant is quite rare, since it is a is rather strange. In some cases, certain risk factors can cause the artery wall itself to proliferate into the lumen, sometimes occluding the vessel completely. This phenomenon usually occurs in small caliber arteries located deep in the brain tissue, which explains its “lacunar” form.
1.5 Stroke of extravascular origin
We use this last type of ischemic stroke as a sort of catch-all, since here we can include all ischemic strokes with unknown causes (up to 20%) or whose origin is not in the blood vessel itself. all ischemic strokes of unknown cause (up to 20%) or whose origin is not found in the blood vessel itself.. This category includes, for example, strokes caused by cysts and tumors that cause compressive phenomena on the artery.
As its name indicates, the “extravascular” origin denotes that it is another element external to the blood vessel that is producing the impingement, such as a tumor, a cyst, an abscess and other elements.
We return to the initial classification criterion since, as we have said, there are two main types of stroke: ischemic and hemorrhagic. Just as the first variant is characterized by a lack of irrigation to the brain, the second occurs when a blood vessel weakens when a blood vessel is weakened and eventually ruptures.. This results in a flooding of the surrounding tissue with blood, which, as you can imagine, can be disastrous for the patient.
Hemorrhagic strokes are much less common than ischemic strokes (they account for 15% of cases) and are generally due to 3 causes. These are summarized in the following list:
- AneurysmAn aneurysm is defined as a ballooning of a blood vessel. Not all aneurysms rupture, but those located in the brain that do give rise to a stroke or hemorrhagic stroke.
- Arteriovenous malformation (AVM)a poor connection between arteries and veins.
- Cerebral amyloid angiopathy (CAA)a disease in which amyloid proteins build up in the walls of the arteries of the brain.
A hemorrhagic stroke can also happen from taking certain drugs or very high blood pressure, although this is less common. It should also be noted that an ischemic stroke can also present bleeding, which makes it fall into both categories at the same time.
We have chosen this classification criterion because it is the simplest of all, although ischemic strokes can also be classified according to their extension and location (total, posterior circulation or lacunar) and, on the other hand, hemorrhagic strokes according to the type of bleeding (intraparenchymal, intraventricular, subarachnoid).
What we mean by these meanings is that the classification of such a complex pathology will depend very much on the criteria used: origin, extent of damage and possible effectsThe parameters used to compartmentalize a disease, for example, are all equally valid. If you have been left wanting more or other opinions, we recommend that you take a look at the bibliography presented at the end of the article.
As you may have noticed, the world of stroke is a vast and tremendously complex one. Ischemic strokes are much more common than hemorrhagic ones because, mainly, they can be caused by more causes (thrombi, embolisms or tumors, for example). On the other hand, hemorrhagic strokes are usually caused by cerebral aneurysms, although only a small percentage of the dilated vessels end up bursting and flooding the brain with blood.