The dangerous period of brainstem infarction is also known as the cerebral edema period, which usually begins to appear at 24 hours and gradually reaches its peak at 1 week to 10 days and is the most dangerous, after which the cerebral edema slowly subsides. Brainstem function is to maintain individual life, including heartbeat, respiration, digestion and a series of other important physiological functions, so the risk of brainstem infarction is higher and there are more complications. Brainstem infarction is most common in the cerebral bridge, and the main pathological changes are brain tissue ischemia, hypoxia, edema, and necrosis, which have an acute onset and mainly manifest as hemiparesis or quadriplegia, high fever, difficulty in swallowing and pronunciation, and impaired consciousness. Brain stem infarction is mostly seen in the elderly and is often caused by hypertension, atherosclerosis and other etiologies. It takes about 2-3 weeks for cerebral edema to completely subside, and in severe brainstem infarction, the extent of cerebral edema is larger, and even the edema period can be more than 1 month.