Lacunar Strokes

The size and location of an ischemic infarct depends on which parts of the brain that the occluded artery supplied 

So far, we have been talking primarily about the results of blocking large arteries.  However, occlusion of the class of small arteries that supply deep forebrain or medial brainstem structures can cause small or "lacunar" strokes. Lacunar strokes, a subtype of ischemic stroke, have earned their name because the area rendered ischemic takes the form of a small lacune or cavity (usually less than 15mm in diameter). 

Although a lacunar stroke may be small, it can lead to major neurologic deficits. A much larger infarct may actually produce a less extensive (or intrusive) neurologic deficit for the patient.  It all depends on exactly what gray and white matter structures are involved!

This specimen is a coronal section through half of the brain.It shows two lacunar infarcts in the putamen, a deep gray matter structure buried deep in the hemisphere.  As far as we know, this patient did not show any specific neurologic deficits related to these infarcts.However, a small infarction located just 50-100 mm more medially would have interrupted fibers in the internal capsule and might have caused paralysis of his arm or leg. Remember that the corticospinal tract forms most of the internal capsule in this posterior region.