Lacunar Stroke
A lacunar stroke is a type of ischemic stroke caused by blockage of small penetrating arteries deep within the brain. These strokes create small cavities (lacunes) in the brain tissue, typically measuring less than 15 millimeters in diameter. Lacunar strokes account for approximately 20-25% of all ischemic strokes and primarily affect the deep structures of the brain such as the basal ganglia, thalamus, internal capsule, and pons. They are strongly associated with chronic hypertension and diabetes.
What is it?
Lacunar strokes result from occlusion of small penetrating arteries (also called perforating arteries or arterioles) that branch directly from larger arteries to supply deep brain structures. These tiny vessels, typically 100-400 micrometers in diameter, are particularly vulnerable to damage from chronic hypertension and other vascular risk factors. When blocked, they cause small areas of brain tissue death that eventually form fluid-filled cavities called lacunes. The term “lacunar” comes from the Latin word “lacuna,” meaning gap or cavity.
The pathological process underlying most lacunar strokes is lipohyalinosis—a degenerative change in the small vessel walls caused by prolonged high blood pressure. This leads to thickening and narrowing of the vessel walls, ultimately resulting in complete occlusion. Lacunar strokes differ from other stroke types in that they don’t result from emboli (blood clots traveling from elsewhere) or large vessel atherosclerosis, though these mechanisms can occasionally cause lacunar-type infarcts. The presence of multiple old lacunar infarcts on brain imaging is associated with an increased risk of cognitive decline and vascular dementia.
Important to Know
Lacunar strokes typically present with one of five classic clinical syndromes depending on their location: pure motor stroke (weakness on one side of the body without sensory loss), pure sensory stroke (numbness or sensory loss on one side without weakness), ataxic hemiparesis (combination of weakness and coordination problems), dysarthria-clumsy hand syndrome (slurred speech with hand clumsiness), or mixed sensorimotor stroke. Unlike cortical strokes, lacunar strokes generally do not cause aphasia, visual field defects, or impaired consciousness because they affect deep brain structures rather than the cortex. Diagnosis is confirmed with brain MRI, which is more sensitive than CT for detecting small acute infarcts, particularly using diffusion-weighted imaging (DWI) sequences. Treatment focuses on acute management (if presenting within the treatment window) and secondary prevention through aggressive blood pressure control, antiplatelet therapy (typically aspirin or clopidogrel), cholesterol management, diabetes control, and lifestyle modifications. The prognosis for recovery from an individual lacunar stroke is generally better than for larger cortical strokes, though recurrent strokes and accumulation of multiple lacunes can lead to significant disability and cognitive impairment over time.