If a patient has dizziness when sitting, consider the following aspects: 1. If the patient has cerebral arteriosclerosis or atrial fibrillation, the sudden appearance of dizziness should be considered to be caused by lesions of the cerebellar brainstem, such as infarction of the cerebellar brainstem, the patient will have dizziness, ataxia, unstable walking, and body tilting to one side. 2. If the dizziness occurs suddenly when the patient is sitting, accompanied by tinnitus and deafness, it should be considered to be caused by Meniere’s disease or vestibular neuronitis, in which the dizziness lasts for a longer period of time and nystagmus can be seen, but the patient will not have inflexible limb movement or visual double vision, which is a symptom of central nervous system deficit.