By Jose Vega MD, PhD 

Updated on August 20, 2023

 Medically reviewed by Nicholas R. Metrus, MD

A thrombotic stroke is a type of ischemic stroke that occurs when a blood clot, also called a thrombus, forms and blocks blood flow through the artery in which it formed.¹

American Stroke Association. Ischemic stroke.

The blood clot may block the flow of oxygen-rich blood to a portion of the brain, causing long-term brain damage. This brain damage caused by a lack of adequate blood supply produces a stroke.

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Types of Thrombotic Stroke

A thrombotic stroke may also be called a cerebral thrombosis, a cerebral infarction or a cerebral infarct.

Thrombotic strokes are divided into two categories based on the size of the area of blockage within the brain: large-vessel thrombosis and small-vessel thrombosis.

Large-vessel stroke occurs in the larger blood-supplying arteries of the brain, such as the carotid artery or middle cerebral artery. Large-vessel thrombotic strokes typically cause substantial symptoms and long-term effects, such as aphasia (trouble with language) or hemiparesis (weakness of one side of the body.)

Small-vessel stroke occurs when blood flow is blocked to a small and deep penetrating arterial blood vessel. This type of stroke is also known as a lacunar stroke or a subcortical stroke. A small-vessel thrombus can also result in a brainstem stroke.² Small-vessel strokes are literally small in size, affecting only a limited area of the brain. Depending on the area impacted by a small thrombotic stroke, it can produce minor effects or it can produce substantial handicaps if it impacts a region of the brain that is responsible for important and noticeable physical or cognitive abilities.

Symptoms and Effects

A thrombotic stroke can occur in any area of the brain, and the immediate symptoms and long-term effects of a thrombotic stroke correlate with the area of the brain that is affected by a lack of blood supply.

Symptoms of a thrombotic stroke may include any combination of the following:³

• Trouble understanding words or trouble speaking

• Sudden confusion

• Loss of consciousness

• Weakness of the face, arm, or leg on one side of the body

• Numbness of the face, arm, or leg on one side of the body

• Blurred vision in one or both eyes

• Double vision

• Sudden, severe headache

• Dizziness

• Difficulty walking

• Loss of balance or coordination

Causes and Risk Factors

There are several causes of thrombotic stroke.

• Atherosclerosis or narrowing of the blood vessels: A thrombotic stroke is most commonly caused by the narrowing of the arteries in the head or neck. Most often caused by atherosclerosis, the arteries become diseased and irregular.⁴ This occurs as a result of high blood pressure, diabetes, and build-up of cholesterol, fat, and debris in sections of the blood vessels. Over time, this material can become "sticky," causing blood cells to collect and form a blood clot. Atherosclerosis and narrowing of the blood vessels in the brain is often referred to as cerebrovascular disease.

• High blood pressure: Persistently high blood pressure, also called hypertension, may cause disease and narrowing of the blood vessels, predisposing to thrombotic strokes. Hypertension and atherosclerosis are conditions that often occur together, which causes even further damage to the blood vessels.

• High cholesterol: High cholesterol levels in your body can cause cholesterol and fat to deposit in the blood vessels, exacerbating the risk of thrombotic stroke.⁵

• Diabetes: Diabetes is a well-known risk factor for thrombotic stroke. It can cause narrowing of large and small blood vessels leading to the formation of a thrombus and consequent stroke.

• Blood clotting disorders: Some blood clotting disorders make it more likely for excessive blood clots to form, increasing the chances of a thrombotic stroke.

• Smoking: Smoking is one of the leading risk factors of stroke and heart disease because it causes damage to the blood vessels throughout the body.⁶

• Recreational drugs: Certain drugs, such as cocaine, methamphetamine, and performance-enhancing substances can promote the slow development of cerebrovascular disease. These drugs may also cause sudden narrowing and or "spasm" of the blood vessels, abruptly closing off blood flow to an area of the brain for a brief period of time.

• Trauma to the blood vessels of the neck: While it is not common, there are instances in which severe trauma can induce the formation of a blood clot, resulting in stroke. 

• Transient ischemic attack: A thrombotic stroke may be preceded by a series of one or more transient ischemic attacks, also known as “mini-strokes” or TIAs.⁷ A TIA may last for a few minutes or hours and is often a sign of an impending stroke. The symptoms of a TIA are similar to those of a stroke.

Stroke Risk Factors in Women

Guidelines for stroke prevention jointly published by the American Heart Association and American Stroke Association note that certain risk factors, including diabetes, hypertension, migraine with aura and atrial fibrillation, are stronger or more prevalent in women than men.⁸

A Word From Verywell

A thrombotic stroke is among the most common causes of stroke. There are a number of treatments for thrombotic stroke, including blood thinners such as TPA and procedures that can help to dissolve and remove a blood clot. If you or a loved one has experienced a thrombotic stroke, you may need to participate in a post-stroke rehabilitation program, which can help with your recovery.

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By Jose Vega MD, PhD

Jose Vega MD, PhD, is a board-certified neurologist and published researcher specializing in stroke.