Demyelinating encephalopathies have either occupying effects, such as pseudotumor-like demyelinating disease, or no occupying effects, such as multiple sclerosis and acute disseminated encephalomyelitis. 1. Pseudotumor-like demyelinating disease: it is an independent lesion of the central nervous system with unique clinical and pathological features, between multiple sclerosis and post-infectious (or post-vaccination) encephalitis. Because of its main manifestations of brain parenchyma occupation and severe neurological deficits, it is very easy to be misdiagnosed as intracranial tumor with occupying effect on imaging. 2. Multiple sclerosis: This disease is mainly due to the damage of nerve myelin, which affects the transmission of information and the emergence of the disease. Patients will have limb weakness, sensory abnormalities, vision loss, ataxia, psychiatric symptoms, etc. Imaging examination usually does not show occupying effect. 2. Acute disseminated encephalomyelitis: This disease mainly involves the brain, brainstem, cerebellar spinal cord and other demyelinating changes, without occupying. It is mostly seen in children and young adults with a history of vaccination. At the onset of the disease, there will be high fever, headache, malaise, muscle pain, etc. In severe cases, there will be convulsions and loss of consciousness. Imaging exams also usually do not show a placeholder effect. When suffering from demyelinating encephalopathy, one should go to the hospital in time and choose the appropriate treatment according to the specific disease.