Patients with delayed-onset encephalopathy usually have difficulty in recovering their mental abilities. Late-onset encephalopathy, also known as carbon monoxide toxic encephalopathy, is a neurological disease in which patients with acute carbon monoxide poisoning become comatose after the onset of the disease, and after a period of pseudo-healing, dementia and other psychiatric symptoms and extrapyramidal symptoms occur suddenly. The specific pathogenesis is not clear, may be due to the brain hypoxia caused by neural demyelination changes. Patients may present with dementia, personality changes, disorientation, etc. Focal signs and symptoms, including hemiparesis, monoparesis, aphasia, sensory loss, cortical blindness, etc., may also be present. Cranial MRI can show demyelinating changes in the brain. Once delayed encephalopathy occurs the treatment is difficult and the prognosis is poor, only a very small number of patients can be cured, the main treatments include hyperbaric oxygen therapy, cerebroprotective therapy, glucocorticoid therapy and so on. Patients with acute carbon monoxide poisoning must be given enough hyperbaric oxygen therapy in time to prevent the occurrence of delayed encephalopathy. Patients who have developed delayed encephalopathy should seek medical treatment in time and under the guidance of doctors, in order to improve the prognosis.