Most of the time, strokes damage brain tissue in the outer part of the brain which is called the cortex, or sometimes called the "lobes" or "hemispheres" of the brain. However, some strokes injure deeper structures underneath the cortex. A stroke in a deep area of the brain (for example, a stroke in the thalamus, the basal ganglia or pons) is called a lacunar stroke. These deeper structures receive their blood flow through a unique set of arteries. Because of the characteristics of these arteries, lacunar strokes happen a little bit differently from other strokes.
A lacunar stroke occurs when one of the arteries that provide blood to the brain's deep structures is blocked. These arteries are small, and 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) can lead to lacunar strokes because it causes a pounding pulse. Since the arteries don't gradually taper down in their size, high blood pressure can directly damage these arteries. High blood pressure also can cause atherosclerosis, a condition in which fatty deposits (plaques) build up along the walls of blood vessels. When atherosclerosis is present, a clot can form inside of one of these small arteries and a small clump or clot can be dislodged by the pounding of high blood pressure, blocking blood flow further along the artery.
Unlike strokes that damage the cortex, lacunar strokes are only rarely caused by a blood clot (also called a "thrombus") that forms elsewhere in the body, such as the neck or heart, and travels through the bloodstream to the brain. After a clot (or any debris) begins to travel through the bloodstream it is called an embolus. It is difficult for an embolus to make its way into the small arteries that can cause a lacunar stroke.
Many of the deep brain organs that can be injured by a lacunar stroke help to relay communication between the brainstem and the brain cortex, or help to coordinate complicated body movements. In a lacunar stroke, brain cells in a relatively small area (measuring from 3 millimeters to as much as 2 centimeters across) are damaged or killed by lack of oxygen. Such a small area of brain destruction is called a lacune. A lacunar stroke involves only a small area of the brain, but it can cause significant disability.
Lacunar strokes account for about 20% of all strokes in the United States.
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:
In a person with prolonged, untreated high blood pressure, multiple lacunar strokes can occur. This can cause additional symptoms to develop, 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 whether stroke symptoms will go away on their own. Get to an emergency room as quickly as possible to get treatment.
Your doctor will ask about your medical history (high blood pressure, heart disease, smoking, high cholesterol and diabetes). He or she will check your vital signs (temperature, pulse, breathing rate and blood pressure) and might order an electrocardiogram (EKG).
Lacunar strokes usually are identified by a computed tomography (CT) scan or magnetic resonance imaging (MRI) scan of your brain. An MRI technique known as diffusion weighted imaging is particularly sensitive for identifying very new lacunar strokes.
If your symptoms continue without improvement during the time you are traveling to an emergency center, it is best to assume that your event is a full-blown stroke, not a TIA. If a lacunar stroke is treated early, full recovery is possible. If medicines restore circulation to the brain quickly, symptoms of a lacunar stroke may go away within hours. If blood supply is interrupted for a longer time, brain injury may be more severe, and symptoms may last for many weeks or months, requiring physical rehabilitation. There may be permanent disability.
You can help to prevent lacunar stroke by preventing or controlling the risk factors for stroke -- high blood pressure, smoking, heart disease and diabetes. If you have high blood pressure or heart disease, follow your doctor's recommendations for modifying your diet and taking your medication. Exercise regularly, eat plenty of fruits and vegetables, and avoid foods filled with saturated fats and cholesterol. If you smoke, quit. If you have diabetes, monitor your blood sugar level frequently, follow your diet, and take your insulin or oral diabetes medication as your doctor has prescribed.
If you have had a lacunar stroke, your doctor may recommend a daily aspirin or other blood-thinning medication, such as ticlopidine (Ticlid) or clopidogrel (Plavix). These medicines may reduce your risk, but their benefit has been more obvious for stroke types other than lacunar strokes. If you have never had a stroke of any kind, you might lower your risk for a first stroke if you take a daily aspirin. There is strong evidence that stroke risk is reduced for women over the age of 45 who take aspirin once every other day. This benefit has not been proven for men.
If doctors are able to provide treatment within three hours after symptoms start, they probably will use with a clot-dissolving medication. Although the blood-thinning medication heparin often is used to treat strokes that affect large arteries, it does not appear to help people with lacunar strokes recover.
A person who has had a lacunar stroke usually is hospitalized so that he or she can be observed in case symptoms worsen. A person with a severe stroke may need help with self-care or feeding. In the hospital, an occupational therapist and a physical therapist can help the person to work around a new disability and to regain strength after brain injury. Commonly, hospitalization is followed by a period of residence at a rehabilitation center, where additional intensive therapy may be given. The goal of rehabilitation is to maximize recovery. To prevent future strokes, it is very important for you to control high blood pressure. It helps to take a daily aspirin or other blood-thinning medication (ticlopidine or clopidogrel).
Call for emergency treatment immediately whenever the symptoms of lacunar stroke occur, even if these symptoms last only a few minutes. For best results, stroke treatment must occur within three hours of the start of symptoms.
People often begin to recover within hours or days of a lacunar stroke. Lacunar strokes have a better rate of recovery than other strokes that involve larger blood vessels. More than 90% of people with a lacunar stroke will recover substantially within the first three months following the stroke.
National Institute of Neurological Disorders and Stroke
P.O. Box 5801
Bethesda, MD 20824
National Stroke Association
9707 E. Easter Lane
Centennial, CO 80112