Severe vertigo and unstable standing are the main manifestations of cerebellar lesions. Due to insufficient blood supply to the brain, the patient can suddenly develop vertigo with visual impairment, weakness of limbs and unsteadiness in standing, mostly occurring during high neck activity. The following are the specific diagnostic contents. 1.Localization diagnosis Analyze the site of the lesion according to the patient’s symptoms and signs. Cerebral hemispheric lesions show contralateral lateral palsy, tongue palsy, limb hemiparesis and hemianopia; cerebellar lesions mainly show severe vertigo, unsteadiness, nystagmus, etc.; brainstem lesions show more complex manifestations, such as crossed palsy, ipsilateral distortion of the mouth, tongue extension, contralateral limb hemiparesis and hyposensitivity. 2.Qualitative diagnosis According to the onset of the disease, the characteristics of the disease and the location of the lesion, analyze the nature of the disease, determine whether it belongs to hemorrhagic or ischemic cerebrovascular disease, the two treatment principles are different, CT or MRI examination can clarify the location and nature of the lesion. 3.Diagnosis of etiology According to the whole process of disease onset, combined with localization and qualitative diagnosis, to find out the specific cause of the disease.