So we’ve been over the 4 Main Types of Strokes. Since ischemic strokes affect around 85% of stroke survivors, I thought it’d be helpful to go into a bit more detail.

Typical Causes

Let’s talk about the two most common causes of ischemic strokes.

Clear model of a human skull with visible blood vessels.


This is the build-up of plaques in blood vessels. Plaques are fatty substances, cholesterol, and/or cell waste. The plaque build-up can cause a blockage in blood vessels. This leads to vessel narrowing and decreased blood flow to cells.

Plaques can also break off and travel to different vessels in the body. If a plaque travels to the vessels of the brain and blocks blood flow, a stroke can happen.

When the inner lining of our blood vessel walls gets damaged, plaques can build-up. The American Heart Association lists the most common causes of blood vessel damage.

  • High cholesterol and fats in the blood
  • High blood pressure
  • Smoking
  • Diabetes

Atrial Fibrillation

Harvard Health notes that 1 in 6 ischemic strokes can be traced to atrial fibrillation (or AFib). AFib is one of the most common types of heart rhythm irregularities.

When someone’s heart is in AFib, the chambers of the heart don’t beat in rhythm. This means that some blood remains in those chambers instead of pumping out.

The leftover blood in these chambers can clot. When a blood clot is pumped out of the heart, it can travel to the brain and cause a stroke.

Types of Ischemic Strokes

Let’s look at the two main types of ischemic strokes, thrombotic and embolic. These are fancy names for blood clots (or particles in the case of some emboli). The difference is in where those clots or particles form and how they get to the brain!


This type of stroke involves a thrombus, or blood clot, which forms in the blood vessels that supply the brain. These reduce or block the blood flow available which leads to brain cell death.

  • A thrombus can cause either sudden onset of symptoms or slow onset over the course of hours/days.
  • It can occur in large or small vessels depending on the size of the thrombus.
  • A thrombus that occurs in the small, deep vessels of the brain is a lacunar infarction. These occur most often in the basal ganglia, internal capsule, thalamus, and brainstem.
  • Thrombotic strokes are most common in adults with high cholesterol, atherosclerosis, and diabetes.


An embolus is a particle, most often a blood clot but can be fat, air, or bacteria. In an embolic stroke, the embolus forms/breaks off in a different part of the body and travels to the brain.

  • The embolus becomes lodged as it travels through smaller blood vessels, blocking off blood flow.
  • When an embolus becomes lodged, it’s normal to see an abrupt onset of issues. It can sometimes become dislodged and symptoms resolve. In other cases, an embolus can cause lasting problems that require extensive therapy.
  • An embolus often occurs with heart disease or after heart surgery.
  • According to Johns Hopkins, around 15% of those who experience an embolic stroke have AFib.

So those are the basics you need to understand how ischemic strokes happen. Over the next few posts, I’ll cover the basics of hemorrhagic strokes and how the effects of a stroke change based on their location. Stay tuned!