Severe cerebral edema causes impaired consciousness, or cerebral edema compresses normal tissue and displaces it, causing brain herniation or changes in vital signs, such as changes in blood pressure and breathing. In severe cases, it causes herniation of the suboccipital foramen, which compresses the medulla oblongata and leads to respiratory and cardiac arrest. Severe cerebral edema should be treated aggressively with aggressive dehydration. In the case of severe cerebral edema causing brain herniation, decompression of the bone flap or extraventricular drainage can be performed to reduce intracranial pressure and allow the patient to pass through the danger period, after which the cerebral edema is often gradually reduced and the symptoms gradually recover.