The clinical manifestation of coma is the loss of the wakefulness-sleep cycle, and the patient is in a continuous deep sleep and cannot wake up. The patient’s perception, attention, thinking, emotion, orientation, judgment, memory and many other mental activities are all lost. The patient does not understand himself or the external environment and does not respond to external stimuli. The patient is unable to perform simple commands. When given a strong painful stimulus, there is no conscious response except for sometimes painful expressions or moans. The causes are as follows: 1. Coma with neurological localization signs Cerebral hemorrhage, cerebral infarction, traumatic brain injury, brain tumor, brain abscess, encephalitis, cerebral parasitosis, and brain herniation, etc. 2.Coma with meningeal irritation signs Various bacterial, viral and fungal meningitis, systemic infections causing false meningitis, cerebral hemorrhage, traumatic brain injury and other blood into the subarachnoid space, brain tumor, brain abscess, encephalitis and other invasion of the subarachnoid space, as well as subarachnoid hemorrhage, intracranial venous thrombosis, high cranial pressure, etc. 3.Coma caused by systemic diseases See serious infections and endocrine and metabolic disorders, electrolyte disorders, etc.