The site of infarction and infarct size vary, and the most likely manifestations are as follows: (1) sudden onset, often at quiet rest or during sleep. The onset peaks within a few hours or 1 to 2 days. (2) Headache, vertigo, tinnitus, hemiplegia, either in a single limb or in one limb, either in the upper limb heavier than the lower limb or in the lower limb heavier than the upper limb, and a variety of conditions such as dysphagia, slurred speech, nausea, vomiting, etc. In severe cases, the patient soon becomes unconscious. Each patient can have several of the above clinical manifestations. (3) Significance of brain CT examination: brain CT examination shows the size and location of cerebral infarction lesions with an accuracy rate of 66.5% to 89.2%, and shows initial brain hemorrhage with an accuracy rate of 100%. Therefore, early CT examination can help in differential diagnosis and exclude lesions such as cerebral hemorrhage. It is very important that the treatment of cerebral hemorrhage and cerebral thrombosis at early onset is distinctly different. When the onset of cerebral infarction is within 24 hours, or the infarct focus is less than 8 mm, or the lesion is at the brainstem and cerebellum, brain CT examination often does not provide a correct diagnosis. It should be reviewed within a short period of time if necessary to avoid delaying treatment. (4) There is a disease called “lacunar cerebral infarction”, in which the patient may be asymptomatic or have mild symptoms, and the disease is detected by CT examination of the brain due to other diseases, and some of them are old lesions. This condition is common in the elderly, and patients often have chronic diseases such as hypertension, atherosclerosis, hyperlipidemia, coronary artery disease, and diabetes. Lacunar cerebral infarction can recur, and some patients eventually develop into symptomatic cerebral infarction, while others have stable conditions that remain unchanged for many years. Therefore, “asymptomatic stroke” in the elderly should be taken seriously and a proactive approach should be taken in prevention.