Strokes come in many forms, the most common of which doctors call a lacunar infarct. So what is a lacunar infarct? This type of stroke involves blockage of one of the main arteries that supply structures deep inside the brain. Several distinct syndromes, or collections of related symptoms, have been described, which can affect the patient’s ability to recover from the stroke and regain normal function.
A Little on Anatomy
The brain is a highly active organ, using a large amount of energy and oxygen to perform its tasks related to integrating information that is gathered by the nervous system and controlling motor functions of the body. Oxygen is delivered to the brain in blood, which is delivered by a complex arterial system. The structures deep within the brain are supplied by arteries that form a circle, called the Circle of Willis, on the base of the brain before branching up into its deeper parts. Blockage of the arteries of the Circle of Willis causes parts of the brain to be starved of oxygen and begin to die, called a hypoxic-ischemic event, an infarct, or a stroke. Because the Circle of Willis is, as its name implies, a circle, if it is blocked, blood can flow around the circle to bypass the blockage and still reach much of the brain, but a small portion will be affected. A lacunar infarct gets its name from the changes that are grossly visible in the brain when it is examined postmortem. The parts of the brain that have died from lack of oxygen form open spaces, which are called lacunae.
There are five different syndromes associated with lacunar infarcts, and which one a patient experiences depends on where in the brain the arterial blockage and subsequent damage to the brain occurs. The most common syndrome is a pure motor stroke, which affects up to half of stroke patients. These patients experience paralysis on one side of the body, often including the face, arm, and leg on the affected side. Sometimes these patients will have numbness or tingling early in the course of the stroke, but this usually passes relatively quickly, while the motor deficits can take months or years to resolve. This syndrome is what many people think of when they picture the symptoms of a stroke, and it has the best prognosis. People with this syndrome recover their motor functions more quickly and more fully than other stroke patients do. Other, less common syndromes include an ataxic variant, in which the patient experiences clumsiness and disorientation on one side of the body; clumsy hand syndrome, in which only the hands are affected and symptoms are most visible during fine motor tasks such as writing; sensory strokes characterized by numbness and tingling in the extremities; and mixed sensory motor strokes, which involve both numbness and paralysis, usually on the same side of the body.
When people ask, what is a lacunar infarct, the simple answer is that it is a stroke. However, because of the complex nature of the brain and its blood supply, a lacunar infarct implies a specific type of stroke, and by coming to this specific diagnosis, doctors can more accurately predict how a patient will recover. Obesity, diabetes, high blood pressure, and being male are all predisposing factors for this type of stroke, but patients generally recover well with good medical care and rehabilitative therapy.