Craniotomy cerebral edema usually takes about 1-2 weeks to persist. The first reason why edema is caused after craniotomy may be due to the compression of the surrounding tissues caused by the primary intracranial lesion, which causes cerebral edema due to ischemia and hypoxia of the brain tissue. In addition, cerebral edema may also be caused by the stretching of brain tissue during the surgery. However, some patients with tumors may have persistent malignant cerebral edema, which may last for more than a month. For patients with intracranial infection after craniotomy, the duration of cerebral edema may be even longer. As long as the infection foci persist, the cerebral edema will also persist.