Lacunar infarction is a concept that integrates pathology, CT, and clinical diagnosis. It is a common disease among the elderly, with a high incidence age group of 60 to 70 years old. Fisher summarized it as: ischemic microinfarction (or softening focus) occurring in the deep perforating arteries (or other small arteries) of the brain, and irregular cavities formed after chronic healing. The diameter of the small arteries involved in the lesions is about 200µm, and the pathological changes are 2 to 20mm cavities or infarctions. The head CT scan shows different degrees of reduced density areas of 2 to 20mm (generally not more than 15mm). At present, more than 20 types of lacunar syndromes can be diagnosed clinically.