Lacunar infarction refers to small penetrating arteries deep in the cerebral hemisphere or brainstem. On the basis of long-term hypertension, the vascular wall undergoes lesions, leading to occlusion of the lumen and forming small infarction foci. Common sites of onset include the putamen, caudate nucleus, internal capsule, thalamus, and pons. The arteries in these areas are mostly small arteries called deep perforating branches, which are actually the terminal branches of cerebral arteries, also known as terminal branches. Since the blood supply range of deep perforating arteries is limited, the blockage of a single branch only causes ischemic necrosis of a very small range of brain tissue, forming the so-called lacunar infarction. Lacunar infarction is a cystic lesion with a diameter of 0.2 to 15 mm, which is multiple and the small infarction foci are only slightly larger than the diameter of the blood vessel. After the necrotic tissue is absorbed, small cystic cavities may remain.