The 6 types of stroke (and their characteristics)

Stroke (CVA) is a medical condition that occurs when blood flow to part of the brain stops. We are facing a pathology of very worrying characteristics, since it is estimated that in the world 17 million people suffer a stroke every year. This translates, depending on the region studied, in about 14 cases per 100,000 inhabitants or, if you prefer, that one in 6 people will suffer a stroke in their lifetime.

The world of strokes is complex both terminologically and classically. For example, first of all we must highlight that cerebrovascular accident, stroke, cerebral infarction, stroke, stroke and cerebrovascular attack are all synonymous: medically, we are talking about the same thing even if we change the words.

Once we have briefly addressed the situation of LCAs at a global level and the terminological conglomerate that define them, it is normal to ask the following question: what types are there? If you have been struck by this question while reading the introductory lines, don't worry. Here we bring you the 6 types of stroke and their characteristics.

• We recommend you read: "Stroke: Warning Signs and Possible Treatments"

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 cut off or reduced, preventing the brain tissue from receiving oxygen and nutrients. Due to this lack of blood flow, cells in the affected tissue begin to die within minutes.

Various studies show truly worrying data regarding this pathology. For example, it is estimated that in 2016 there were almost 8,500 deaths from strokes in Chile, which translates to 15% of deaths and causes of disability combined throughout the country.

In addition to all this, it should be noted that approximately 30% of stroke survivors have a disability significant 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 just the beginning of the road.

What are the types of stroke?

The epidemiological data are clear and concise, as the numbers do not lie. Unfortunately, the words are subject to personal interpretation and, therefore, we are now entering a bit of a mess. We are going to describe the types of stroke according to professional portals, such as the Mayo Clinic and the United States National Library of Medicine.

Even so, we must note that the classification criteria varies 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 one of them where things get a bit complicated. Without further ado, we get to it.

1. Ischemic stroke

An ischemic stroke is one that happens when an artery becomes blocked, usually from a blood clot or thrombus. This "plug" partially or totally limits blood flow, reducing the amount of oxygen that reaches the brain. It is the most common type of stroke, responding to 80-85% of cases. In countries like Spain, it is reported that there are about 150-200 cases per 100,000 inhabitants, generally in adulthood or old age. Next, we present each of its variants.

1.1 Ischemic stroke of vascular and hemodynamic origin

It is characterized by an arterial stenosis (vasoconstriction) reactive to a multitude of processes. Usually is due to a decrease in cardiac output, that is, the volume of blood expelled by a ventricle of the heart in one minute or, failing that, by severe and sustained blood pressure.

1.2 Of intravascular origin: thrombotic or atherothrombotic stroke

We are facing atherosclerosis phenomena, that is, the clogging of the arteries by lipids, cholesterol and other substances. The thrombotic phenomenon is the one that occurs when a clot forms in a normal artery, while atherothrombosis occurs when the plug is established in an injured area preexisting.

Risk factors for thrombotic and atherothrombotic strokes are obesity, hypertension, diabetes, or increased blood cholesterol. For different 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 especially 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 upper chest and neck or in the heart. This plug or plunger detaches from the place of origin and, after traveling through the bloodstream, ends up plugging a blood vessel with a smaller diameter than in the place 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, and even an air bubble. Actually, anything that hinders blood flow that originates in a place other than the one it is plugging can be considered an embolus.

1.4 Lacunar stroke

We started to spin fine, because this variant it's quite strange. In some cases, certain risk factors can cause the artery wall itself to proliferate towards its lumen, sometimes completely occluding the vessel. This phenomenon usually occurs in small-caliber arteries located deep in the brain tissue, which explains its "lacunar" shape.

1.5 Stroke of extravascular origin

We use this last type of ischemic stroke as a kind of mixed bag, since here we can include all ischemic strokes of unknown causes (up to 20%) or whose origin is not in the blood vessel itself. In this category would fall, for example, strokes that are produced 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 vessel. the blood that is causing the clamping, such as a tumor, a cyst, an abscess and others elements.

2. Hemorrhagic stroke

We return to the initial classification criteria because, 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 blood supply to the brain, the second occurs when a blood vessel becomes weak and eventually ruptures. This causes a flood 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 ones (they respond to 15% of cases) and are generally due to 3 causes. We will briefly tell you about them in the following list:

• Aneurysm: An aneurysm is defined as a bulging of a blood vessel. Not all aneurysms rupture, but those located in the brain that do so lead to a CVA or hemorrhagic stroke.
• Arteriovenous malformation (AVM): a bad connection between arteries and veins.
• Cerebral amyloid angiopathy (ACA): a disease in which amyloid proteins accumulate in the walls of the arteries of the brain.

A hemorrhagic stroke can also occur from the use of certain drugs or very high blood pressure, although this is less common. It is also necessary to emphasize that an ischemic stroke can present bleeding, which makes it into both categories at the same time.

Final thoughts

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 localization (total, posterior or lacunar circulation) and, on the other hand, hemorrhagic 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 a lot on the criteria used: origin, extent of damage and possible effects, for example, they are all equally valid parameters to compartmentalize a disease. If you have been wanting more or other opinions, we recommend that you take a look at the bibliography presented at the end of the article.

Resume

As you may have seen, the world of strokes is a vast and tremendously complex one. Ischemic strokes are much more common than hemorrhagic ones because, mainly, they can be produced by more causes (thrombi, embolism or tumors, for example). On the other hand, hemorrhagic strokes are usually caused by brain aneurysms, although only a small percentage of dilated vessels end up bursting and flooding the brain with blood.

Bibliographic references

• What is a stroke? Clinicbarcelona.org. Picked up on December 7 at https://www.clinicbarcelona.org/asistencia/enfermedades/ictus/definicion
• What is a stroke? RITHMI.com. Picked up on December 7 at https://rithmi.com/que-es-un-ictus/#:~:text=El%20ictus%20o%20m%C3%A1s%20com%C3%BAnmente, blood% 20que% 20 reaches% 20% 20brain.
• Stroke, medlineplus.gov. Picked up on December 7 at https://medlineplus.gov/spanish/ency/article/000726.htm
• Swords. G., Abad, L. M., & Bermejo, R. M. H. (2016). Chapter 4: Stroke and other neurological emergencies. FMC-Continuing Medical Education in Primary Care, 23 (9), 40-50.
• Gutiérrez-Zúñiga, R., Fuentes, B., & Díez-Tejedor, E. (2019). Ischemic stroke. Cerebral infarction and transient ischemic attack. Medicine-Accredited Continuing Medical Education Program, 12 (70), 4085-4096.