Loss of arousal state in coma patients is clinically manifested by the disappearance of the patient’s arousal-sleep cycle and the patient is in a persistent deep sleep, unable to wake up. The patient’s perception, attention, thinking, emotion, orientation, judgment, memory and many other mental activities are all lost. There is no understanding of oneself and the external environment, and no response to external stimuli. Inability to carry out simple commands. When given strong painful stimuli, there is no conscious response at all, except for sometimes a pained expression or a moan. Diagnostic methods for loss of arousal state 1. Locked-in syndrome: Locked-in syndrome (locked?insyndrome) is also known as loss of outgoing state (deafferentedstate). The patient remains alert and aware of his or her situation, but the limbs are paralyzed and the cerebral nerves below the oculomotor nerves are paralyzed, which is caused by bilateral ventral lesions of the cerebral pontine bridges, involving the corticospinal tracts, cortical pontine bridges and cortical medulla oblongata tracts, and the patient is conscious and awake, but can only show his or her signals with vertical eye movements and blinking. This syndrome is commonly caused by the basilar artery thrombosis caused by the bridge infarction, other causes are brainstem tumors and central pontine myelinolysis (centralpontinemyelinolysis), severe polyneuropathy, especially Guillain-Barré syndrome, myasthenia gravis, and the use of neuromuscular junction blocking drugs can also appear in the paralysis similar to the atresia syndrome. 2.Persistent vegetative state: Persistent vegetative state (persistentvegetativestate) patients lose cognitive neurological functions, but retain autonomic functions such as cardiac activity, respiration and maintenance of blood pressure. This state occurs after coma and is characterized by lack of awareness of surrounding objects or cognitive deficits, but the sleep-wake cycle is maintained. Spontaneous movements may be present, and eyes may open in response to external stimuli, but there is no speech or obedience to commands. Many syndromes that are not precisely defined are used as synonyms for persistent vegetative states, including alpha; coma, neocorticaldeath, and persistentunconsciousness. These names lack precision and should be avoided if possible. The diagnosis of this disorder should be made cautiously and only after a long period of observation.