A stroke occurs when blood flow to a part of the brain is interrupted, depriving brain cells of oxygen and nutrients. Without prompt intervention, brain cells can die, leading to lasting damage. One specific type of stroke, known as a lacunar stroke, affects the brain’s small, deep arteries. These strokes are distinct from other forms of stroke due to their size and location within the brain’s intricate network of blood vessels.
Understanding Lacunar Stroke
The term “lacunar” originates from the Latin word “lacune,” meaning a pond or pit, referring to the small cavity that forms in the brain tissue after a lacunar stroke. This cavity develops when a tiny blood vessel deep within the brain becomes blocked, leading to a localized area of tissue death. Lacunar strokes are notably small, typically measuring less than 15 to 20 millimeters in diameter.
These strokes specifically impact the small penetrating arteries that supply blood to deep brain structures, such as the basal ganglia, thalamus, brainstem, internal capsule, and corona radiata. Unlike larger arteries, these small vessels often lack collateral circulation, making them particularly vulnerable to blockages. Lacunar strokes constitute a significant portion of all ischemic strokes, accounting for approximately 20% to 25% of cases.
Recognizing the Signs
The symptoms of a lacunar stroke depend on the specific area of the brain affected by the small blockage. While they can present with various neurological deficits, certain patterns, known as lacunar syndromes, are commonly observed. These syndromes are characterized by the absence of “cortical signs” such as aphasia (language difficulties), neglect (inattention to one side of the body), or visual field defects, which are more typical of strokes affecting the brain’s outer layers.
Common lacunar syndromes include:
- Pure motor hemiparesis, involving weakness or paralysis on one side of the body, often without sensory changes.
- Pure sensory stroke, characterized by numbness or abnormal sensations on one side of the body, but without motor weakness.
- Ataxic hemiparesis, identified by a combination of weakness and clumsiness on one side of the body, often affecting the leg more than the arm.
- Dysarthria-clumsy hand syndrome, presenting with difficulty speaking and clumsiness in one hand, particularly during fine motor tasks.
Causes and Risk Factors
Lacunar strokes are primarily associated with small vessel disease, a condition where the brain’s tiny blood vessels become damaged. This damage often results from long-term exposure to several underlying health conditions and lifestyle factors. The most significant contributor to lacunar strokes is chronic high blood pressure, also known as hypertension. Uncontrolled hypertension directly damages the small arteries, leading to thickening and hardening of their walls.
Diabetes is another risk factor, increasing the likelihood of lacunar stroke by damaging blood vessels and contributing to high blood pressure. High cholesterol levels can also contribute to the narrowing and hardening of blood vessels. Smoking significantly elevates the risk due to its damaging effects on arteries. While advanced age naturally increases stroke risk, individuals across various age groups can experience lacunar strokes if these risk factors are present. Small clots originating from the heart or larger arteries can also block these small vessels.
Diagnosis and Management
Diagnosing a lacunar stroke involves a comprehensive evaluation, with brain imaging playing a central role. Magnetic Resonance Imaging (MRI) is more sensitive than Computed Tomography (CT) scans for detecting the small lesions characteristic of lacunar strokes, especially in the acute phase. While CT scans can provide initial information, they may miss smaller or very recent lacunar infarcts. Advanced MRI techniques, such as diffusion-weighted imaging (DWI), are effective in identifying acute lacunar infarcts.
Immediate management of an acute lacunar stroke focuses on restoring blood flow and preventing further damage. For eligible patients, thrombolytic therapy, which involves clot-dissolving medications, may be administered if treatment can begin within a few hours of symptom onset. Unlike some larger strokes, mechanical thrombectomy, a surgical procedure to remove clots, is not an option for lacunar strokes due to the very small size of the affected arteries. Controlling blood pressure is also an acute treatment goal.
Long-term management and prevention of recurrent lacunar strokes focus on controlling underlying risk factors. Lifestyle modifications are important, including adopting a heart-healthy diet, engaging in regular physical activity, quitting smoking, and moderating alcohol consumption. Medications are often prescribed to manage chronic conditions, such as antiplatelet drugs to prevent new clots, blood pressure medications, and cholesterol-lowering drugs. Rehabilitation therapy, including physical and occupational therapy, is also important for recovery to help individuals regain function and adapt to any lasting deficits.