Brain CT hypodense shadow, part of it belongs to the problematic, suggesting that there are corresponding parts of the abnormal lesions, need to confirm the diagnosis of the specific lesion status, and then do the standardized treatment. Under normal circumstances, brain CT results of corticomedullary demarcation is clear, bilateral brain tissue symmetry. Localized hypodensities found on examination may be normal brain tissue, such as ventricles. The presence of hypodense shadows in parts of the brain that should not be hypodense suggests the presence of corresponding lesions. Common causes include cerebral infarction, infection, and brain tumor, etc., which need to be combined with the characteristics of the lesion itself and the enhancement characteristics to make a comprehensive judgment. Clinically, the presence of low-density shadows on CT, accompanied by obvious headache, dizziness, epilepsy, and abnormal consciousness, etc., requires timely medical observation, and if necessary, MRI and enhancement examination are needed to make a comprehensive judgment. After diagnosing the condition, standardized treatment should be carried out under the guidance of clinicians.