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All About Lacunar Strokes

What is a Lacunar Stroke?

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Updated May 28, 2014

50s man with gray hair lying in hospital bed.
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Lacunar strokes are strokes caused by the occlusion of a small branch of a larger blood vessel. Because of the way blood vessels divide in the brain, lacunar strokes tend to occur in areas located away from the surface of the brain, where many of the smaller blood vessel branches are located. As most brain areas perform a limited set of brain functions, the collection of symptoms of a given lacunar stroke usually falls within one of five categories of symptoms known to be caused by damage in these areas. They include the following:

Pure Motor Strokes

Pure motor strokes are the most common type of lacunar strokes, accounting for more than 50% of all cases. Some people use the term "pure motor hemiparesis" to describe pure motor strokes, though this is redundant. The word hemiparesis means weakness on one side of the body, and weakness -- medically speaking -- is a word that only applies to the motor components of the nervous system.

Pure motor strokes usually involve the following parts of the brain:


All of these areas contain fibers that connect the "brain cortex" the area of the nervous system where the orders to initiate voluntary movements (walking, tapping your foot) first originate. These areas of the nervous system activate muscles all over the body to move. In most cases, the result of strokes in these areas mimics the inability that a puppeteer would have moving a marionette's wooden arm if the string that connected it to its handle was cut. In this example, the puppeteer represents the brain cortex, while the strings that allow the puppeteer to move the marionette's body parts represent the areas affected in a pure motor lacunar stroke.

Symptoms of Pure Motor Lacunar Stroke

Pure motor strokes cause partial or complete weakness in the face, arm and leg on one side of the body. The weakness can be in any of these parts alone, or in combination with either of the other two. Most commonly, pure motor strokes cause either a combination of arm and leg weakness, sparing the face, or a combination of arm, leg, and face weakness. However, symptoms can also occur in any one of these parts alone.

By definition, in pure motor strokes there is no loss of sensation anywhere in the body, and no visual or speech symptoms.

Pure Sensory Lacunar Strokes

As their name implies, pure sensory lacunar strokes are strokes in which the only symptoms are sensory abnormalities, such as numbness or unusual perception of pain, temperature or pressure (see below). The overwhelming majority of pure sensory lacunar strokes affects a brain area called the thalamus, an area that is heavily involved in processing the senses from all over the body. Sensations affected by a pure sensory stroke include touch, pain, temperature, pressure, vision, hearing, and taste.

Symptoms of Pure Sensory Lacunar Stroke

Most cases of pure sensory lacunar stroke produce absent or abnormal sensation in the face, arm, leg, thorax, genitals, and anus, but only on one side of the body. In many cases, however, different body parts such as the fingers, the foot, or the mouth on one side are affected in isolation. A common type of pure sensory lacunar stroke is called Dejerine Roussy, or Central Pain Syndrome.

Sensorimotor Lacunar Stroke

This type of lacunar stroke syndrome results from the blockage of a vessel that supplies both the thalamus and the adjacent posterior internal capsule.

Symptoms of Sensorimotor Lacunar Stroke

Because both a sensory and a motor area of the brain are affected by this kind of stroke, its symptoms include both sensory loss (damage to thalamus) and hemiparesis or hemiplegia (damage to internal capsule). Both the sensory and the motor abnormalities are felt on the same side of the body.

Ataxic Hemiparesis

This type of stroke is most commonly caused by lack of blood flow to one of the following areas of the brain:

Symptoms of Ataxic Hemiparesis

Lacunar strokes in certain parts of these areas, which can also cause pure motor lacunar symptoms, can cause wobbliness and weakness in the arm or leg on one side of the body. Typically, the wobbliness (ataxia) is a much more bothersome symptom than the weakness in the affected arm or leg. The face is not usually involved.

Dysarthria Clumsy-Hand Syndrome

By definition, dysarthria clumsy-hand syndrome is a combination of symptoms caused by a lacunar stroke affecting the anterior portion of the internal capsule. In true cases of this syndrome, people suffer from both dysarthria and a clumsy hand.

Symptoms of Dysarthria Clumsy-Hand Syndrome

As the name implies, a prominent feature of this syndrome is a disorder of speech called dysarthria. For the most part, dysarthria can be defined as difficulty pronouncing or forming words due to inadequate movements of the muscles in the voice box, also known as the larynx, the tongue, and other muscles in the mouth.

Aside from dysarthria, people with this syndrome complain of clumsiness of hand movements on one side of the body. Usually the affected hand has normal strength, but people complain of difficulty with fine movements such as writing, tying a shoelace, or playing the piano.

Source:
J. P. Mohr, Dennis W. Choi, James C. Grotta, Bryce Weir, Phillip A. Wolf Stroke: Pathophysiology, Diagnosis, and Management Churchill Livingstone; 4th edition (2004)

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