Which Types of Strokes Are the Most Severe?

All types of stroke are significant, but some strokes cause more severe disability or even death.

There are a few categories of strokes that are more likely to result in worse outcomes. These include:

  • Brainstem strokes
  • Bilateral strokes
  • Hemorrhagic strokes
  • Large strokes

If you or a loved one has had one of these more severe types of strokes, you may have a long recovery or even a long lasting and substantial change in your abilities.

Brainstem Strokes

The brainstem connects all of the nerve impulses that go from from the brain to the body, which is why brainstem strokes can be even more devastating than a spinal cord injury.

The brainstem also controls many of our most important functions, such as breathing, blood pressure, and heart rate, and contains the brain's awareness center, which allows us to stay conscious of the world around us. A brainstem stroke, even if it is small in size, may lead to hemiplegia, paralysis, or changes in vision. Depending on the location of a stroke within the brainstem, a brainstem stroke can result in long term unconsciousness.

Bilateral Watershed Strokes

Watershed strokes affect areas of the brain that are referred to as the "watershed areas." These areas receive their blood supply from the tiniest end branches of blood vessels, and therefore they require adequate blood pressure and blood volume to ensure that enough blood flows through them at all times.

Because of this, watershed areas on both sides of the brain are at high risk of developing ischemia, or lack of blood flow during certain conditions. This can happen during times of extremely low blood pressure, which can be caused by situations such as dehydration, heart attacks, and sepsis (widespread infections.) Advanced carotid stenosis (clogging of the neck arteries) on both sides of the neck is one of the risk factors for this type of stroke.

Watershed strokes produce severe disability because they impact movement on both sides of the body.

Hemorrhagic Strokes

Hemorrhagic strokes involve bleeding in the brain. There are multiple reasons why people develop bleeding in the brain, and some of the most common include:

Hemorrhagic strokes are extremely dangerous because blood in the brain can sometimes lead to further complications such as hydrocephalus, increased intracranial pressure, and blood vessel spasms. If not treated aggressively, these conditions can lead to severe brain damage and even death. This is why even minor episodes of bleeding in the brain require emergency evaluation.

Large Thrombotic Strokes

Thrombotic strokes are caused by large blood clots which either form inside of, or migrate into, one of the main blood vessels of the brain. These large blood clots are especially dangerous because they can completely stop blood from flowing through the largest, and thus most important, blood vessels in the brain.

The so-called “malignant middle cerebral artery (MCA) syndrome” is an example of such as stroke.

Here, the MCA is blocked by a large blood clot causing the massive infarction (i.e., death) of almost one entire side of the brain. Swelling, which is a combination of fluid and inflammatory cells, ensues as a result of a large stroke. The swelling causes a rapid increase in brain pressure throughout the entire brain. In turn, this high pressure leads to global brain dysfunction, impaired consciousness and very often, to brain herniation (significant pressure and pushing on the brain) and death.

Brain Death

Sometimes severe strokes can produce so much damage to the brain that the brain becomes unable to function in a way that sustains life, which is a condition called brain death.


A Word From Verywell

It can be shocking to hear that you or a loved one has had a stroke. And strokes definitely vary in severity, prognosis and long term effects. The most severe types of strokes can produce significant outcomes that may alter your life or the lives of your loved ones forever.

Many people do experience a degree of recovery, even from severe strokes. It may take some time for the stroke to stabilize and for you and your loved ones to gain an idea of what to expect as far as the long term stroke outcome.


Critical Care Management of Acute Ischemic Stroke. Bevers MB, Kimberly WT, Curr Treat Options Cardiovasc Med. 2017 Jun;19(6):41