The brain CT hypointense shadow is an abnormal manifestation of an abnormal lesion of brain tissue. In this case, specific analysis is needed: 1. If the patient has an acute onset and has inflexible limb function, ischemic brain tissue changes should be considered, such as cerebral infarction disease. 2. If the patient has a long-term headache with nausea and vomiting, the hypointense foci may be caused by brain tumor, which is more serious. 3. If the hypointense shadow of brain CT is a more uniform density foci, it may be caused by general cerebral edema, which is relatively better in this case. It is necessary to improve the CT scan or MRI scan of the head to clarify the nature of the hypointensity and then treat the symptoms.