Introduction:
The term lacune has been used in the medical literature for more than one hundred and fifty years. It was used to describe a small cavity that remained after the healing of a minor stroke. After a period of confusion, the term was reused again in the medical literature in the 1960s. The advancements in imaging modalities (like computerized tomography and magnetic resonance imaging) have enabled the detection of a lacuna in vivo. Other improved diagnostic techniques have proved that it is also caused by conditions other than hypertension.
What Is Lacunar Syndrome?
They are the clinical presentation of lacunar infarction. The occlusion of a penetrating artery from a bigger cerebral artery causes a subcortical lesion more than 15 mm in diameter. This is called lacunar infarction. A lacunar stroke occurs when one of the small arteries to the deeper part of the brain is blocked. According to the National Institute of Health (NIH), lacunar stroke comprises about one-fifth of all strokes.
How Was Lacune and Lacunar Infarcts Discovered?
A French physician named Dechambre is prestigiously thought to have used the word lacune for the first time. He used the term to describe a cavity that formed in the core of infarcts in the brain after the liquefaction of the infarct. It is derived from a Latin word meaning a space. Max Durand-Fardel described the term better as healed infarcts. In 1901, Pierre Marie described it as ‘small softening caused by atherosclerosis'. Charles Miller Fischer, in the 1960s, naked the beginning of the modern era of lacunar infarcts. He redescribed it as ‘small deep cerebral infarcts.’
What Are the Symptoms of Lacunar Syndrome?
Lacunar infarcts may not always show any signs or symptoms. They are often seen in brain scans before people know it. On the other hand, while they show symptoms, they may come suddenly without warning. The classic symptoms of the lacunar syndrome are pure motor hemiparesis, pure sensory stroke, sensorimotor stroke, ataxic hemiparesis, and clumsy-hand dysarthria. The other symptoms can include;
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Slurred speech.
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Difficulty in raising hands.
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Drooping of one side of the face.
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Numbness is usually on one side of the body.
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Difficulty in walking.
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Headache.
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Loss of consciousness.
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Coma.
What Are the Types of Lacunar Syndrome?
However, the five syndromes that are encountered most frequently are:
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Pure Moto Hemiparesis: This is the first observed type of lacunar syndrome. This is the most common type of lacunar syndrome, accounting for about half to two third of the reported cases. Fischer and Curry describe it as ‘paralysis of the face, arm, and leg on one side, unaccompanied by sensory signs, visual field defect, dysphasia (difficulty in speaking) or apractagnosia (difficulty in organizing or doing combined activities)’. It was later amended to exclude the involvement of the face, transient numbness, or subjective heaviness of the affected limbs at the onset of the motor deficit. The course of symptoms of the disease appears to be stuttering, with the symptoms appearing within several hours. The clinical course is more benign when compared to the other types of hemiplegia. The recovery is more extensive when the hemiplegia is incomplete.
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Pure Sensory Stroke: It is less common than pure motor hemiparesis. Studies have shown that the thalamus is the affected area in most cases of pure sensory stroke. The lesions are very small. Hence the CT scan of these patients may not reveal any abnormality. Brain Imaging studies like computed tomography (CT scan) and magnetic resonance imaging (MRI) have revealed other anatomic associations like cortical infarct in the middle cerebral artery region and the centrum thalamocortical pathway. The clinical presentations can include a small hemorrhage in the internal capsule of the cerebral cortex and the thalamus. A transient numbness in one side of the body is observed. The condition is usually benign and will resolve within a few days.
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Sensorimotor Stroke: This is caused by a small deep lacunar infarct. Lesions in parts of the thalamus, internal capsule, caudate and putamen, and lateral pons cause this type of lacunar syndrome. Magnetic imaging resonance studies show that the infarct causing a sensorimotor stroke is more significant than any other lacunar syndrome. Its frequency, when compared to the other lacunar syndromes, is high as thirty-eight percent.
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Ataxic Hemiparesis: Fischer and Cole described this condition as ‘weakness of the lower limb, especially the ankle and toes, and a Babinski sign, associated with striking dysmetria (inability to do complex movements) of the arm and leg on the same side.’ Babiski sign can be described as when stimulation of the lateral plantar of the foot causes an extension or upward movement of the big toe. Transient paresthesia, with a wavering course of the symptoms, is also seen. It can take some days to weeks for improvement. In some conditions, the hemiparesis improves while ataxia (the inability to balance, walk and speak) remains the same.
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Dysarthria-Clumsy Hand Syndrome: A combination of official weakness, severe dysarthria (the difficulty to speak), and dysphagia (difficulty swallowing), with mild weakness and clumsiness in the hands are seen in this condition. It accounts for about two to sixteen percent of the lacunar syndrome. The overall prognosis is favorable in this condition.
How Is Lacunar Syndrome Diagnosed?
A detailed evaluation of the larger arteries should be done:
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CT Scan: It can be used in the diagnosis but has a low chance of detecting small infarcts that might cause lacunar syndrome. Studies show that less than forty percent of lacunar syndrome patients showed any lesion in the CT scan.
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MRI Scan: This showed a higher sensitivity to the lesions in the lacunar syndrome. MRI diffusion-weighted imaging (DWI) technique shows the highest sensitivity and specificity in diagnosing small subcortical lesions. It has an accuracy of 95%. It also helps to diagnose lacunar infarcts with an embolic source.
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Cerebral Angiography: It is also done in patients with lacunar syndrome.
How Is Lacunar Syndrome Managed?
The treatment interventions for the condition can include thrombolytic therapy, secondary prevention, and carotid revascularization. Studies show that intravenous (IV) tissue plasminogen activator (t-PA) within 3 hours of symptom onset was beneficial irrespective of the type of stroke. Carotid endarterectomy, a surgical procedure to remove the plaques in the carotid artery, has also been beneficial. Fischer stresses the importance of maintaining zero high blood pressure to eliminate all possible chances of another stroke.
Conclusion:
Contrary to the other types of stroke, patients with lacunar syndrome improve and have a better prognosis. However, the prognosis can be affected if the deficit is extensive. Studies show a mortality rate of one percent for the condition.
