Lacunar Stroke

What Is It?

A lacunar stroke occurs when blood flowing in small arteries leading to the brain is blocked. These arteries are 0.1 to 0.3 millimeters in diameter. They branch from larger arteries near the underside of the brain. They carry blood to the brain's deeper regions, such as the thalamus, basal ganglia and pons. In a lacunar stroke, a blood clot (thrombus) blocks blood flow. The blood clot can form inside the small artery because the artery has been damaged. A clot can also form in a large artery in the neck or chest, break loose and travel (as an "embolus") in the bloodstream to lodge in these small brain arteries. Clots typically form because an artery has become damaged by atherosclerosis, a condition in which fatty deposits (plaques) build up along the walls of blood vessels.

The small arteries that may cause a lacunar stroke are uniquely vulnerable. Unlike most arteries, which gradually taper to a smaller size, the arteries of a lacunar stroke branch directly off of a large, high pressure, heavily muscled main artery. High blood pressure (hypertension) is a major contributor to lacunar strokes because of the pounding pulse it causes. High blood pressure can cause direct damage to these arteries. It also can dislodge small clumps or clots that can block blood flow.

When a blood clot blocks one of the brain's small arteries, brain cells in a relatively small area (3 millimeters to 2 centimeters) are damaged or killed by lack of oxygen. These small areas of brain destruction are called lacunes. Lacunar strokes account for about 20 percent of all strokes in the United States.

Symptoms

The symptoms of lacunar stroke vary depending on the part of the brain that is deprived of its blood supply. Different areas of the brain are responsible for different functions, such as sensation, movement, sight, speech, balance and coordination.

Symptoms can include:

• Weakness or paralysis of the face, arm, leg, foot or toes
• Sudden numbness
• Difficulty walking
• Difficulty speaking
• Clumsiness of a hand or arm
• Weakness or paralysis of eye muscles
• Other neurological symptoms

In a person with prolonged, untreated high blood pressure, many areas of brain destruction can form, causing additional symptoms, including emotional behavior and dementia.

The sudden appearance of one or more of these symptoms is a warning sign that a stroke may be in progress. Sometimes, the small clots that can cause a lacunar stroke interfere with blood flow only for a few minutes. If the clot dissolves before damage is done, then symptoms can begin to improve within minutes and may go away completely. When symptoms go away without treatment and full recovery occurs within 24 hours, the event is called a transient ischemic attack (TIA). Never decide to "wait and see" if you are having stroke symptoms. Get to an emergency room as quickly as possible to get treatment.