With all of the terminology that surrounds strokes, it is sometimes difficult to keep things straight. Many patients know what ischemic and hemorrhagic strokes are, but the definition of a lacunar stroke escapes them. What’s worse, many physicians and medical support staff can throw around the terms interchangeably without fully explaining them to the patient. This can lead to confusion and fearfulness in asking for repeated explanations from each professional.
In fact, a lacunar stroke is a subtype of ischemic strokes. This means that the brain tissue is damaged due to a mechanical blockage of the artery supplying the brain. In typical ischemic strokes, a large artery is blocked, causing larger tissue damage, and more severe deficits. Lacunar strokes are blockages of much smaller arteries that reside deep in brain tissue. It has several different types, and understanding the exact pathophysiology can help you understand the deficits you are experiencing.
Anatomy and Pathophysiology
Lacunar is Latin for empty space, and it was named that because post-mortem studies on stroke patients found that the infarcts created small injured spaces in the deep brain tissue. Most of these strokes arise from changes that occur in the linings of small arteries, and this occludes blood flow into centrally located brain structures. The putamen, caudate nucleus, thalamus, and pons (areas deep in the brain) among many other structures are generally the ones that show injury from a lacunar stroke. These structures have both specific sensory and motor components that determine their symptomology.
The arteries that are affected are the smaller ones that branch off of main brain arteries, such as those in the circle of Willis, the basilar arteries, and arteries of the cerebellum. Since the impacted vessels are so small, high blood pressure can cause them to thicken. The force the small muscles in the artery need to exert under high pressure situations makes the muscle increase in size. This increase affects the lumen diameter, and it can lead to unintended occlusion of the arteries.
Types of Lacunar Strokes
The symptoms of lacunar strokes depend on what area of the brain the decrease in blood flow impacts. In general, doctors have outlined five different groups of symptoms that relate to specific areas of the midbrain. Although the symptoms were used in the past to determine where a lacunar stroke took place, they are now diagnosed with the help of imaging studies. However, the symptoms are still indicative of the area of injury. For instance, a pure motor stroke is the most common type of lacunar stroke, and it affects the corona radiata, the posterior limb on the internal capsule, and the basis pontis. The most common symptom of this type of stroke is hemiparesis, or paralysis of one side of the body.
A pure sensory stroke is characterized by numbness, tingling, pain, or even burning sensatkion on one side of the body. Other lacunar strokes are not as easily categorized. One type is ataxic hemiparesis, and it is the second most common form of this type of stroke. It is identified by clumsiness and weakness in the side opposite the side of the lacunar stroke. Dysarthia and clumsy hand lacunar syndrome generally manifest as difficulty speaking and difficulty using one hand, like when writing. Finally, a mixed sensorimotor stroke displays paralysis on one side of the body, and numbness, tingling, or even pain on the opposite side.
As with all strokes, controlling high blood pressure, cholesterol, and diabetes are the important points to remember when trying to prevent them, and this is certainly true of lacunar strokes. Poor control of these risk factors may lead to recurrence of more lacunes that may or may not be immediately symptomatic. When the numbers of lacunes start to accumulate in the brain, this may lead to problems with cognitive functions.
Even with a moderate increase in cholesterol levels, the small vessels can become narrowed due to increasing intraluminal plaques. In other words, it does not take a great deal of cholesterol to block off a vessel so small. The same is true for the effects of diabetes.Getting these conditions under control can save brain tissue.
One of the most important variables to control is your blood pressure. Even small increases in pressure can stress the musculature of the small vessels in the brain. When these muscles in the arteries work hard and become larger, they can block the passageway of blood. High blood pressure is a factor in hemorrhagic strokes, but many do not realize that it can affect ischemic stroke risks, as well. Only by controlling blood pressure through diet, exercise, and medications, can you prevent the devastating symptoms of lacunar strokes.
References for your consideration