Brainstem hemorrhage is a very serious organic brain disease, and edema will appear immediately once the hemorrhage occurs. In the early stage, if the edema is not very obvious, the low-density edema band next to the high-density shadow caused by brain hemorrhage is not observed on cranial CT, and it takes about 24 hours for the edema to reach the first peak, which can be clearly observed on CT. Thereafter, the edema will still continue to increase and will reach a second peak the next day, i.e. 48 hours. After reaching the peak, the edema will continue to exist for a period of time, which varies depending on the size of the hemorrhage and lasts about 10-14 days. After that, the edema will gradually subside, taking about 4 weeks or more to completely subside. The high-density shadow of the hemorrhage will disappear before the low-density edema band, but the patient still needs to be monitored because the edema may also lead to impaired brainstem function and cause respiratory and circulatory impairment.