Disorders of consciousness, clinically, are mainly classified into three degrees according to the level of consciousness of the patient, namely drowsiness, somnolence and coma. Somnolence mainly refers to the patient’s decreased level of consciousness, and the patient mainly shows drowsiness, and if given a call or push, the patient is able to respond briefly. In terms of corneal reflexes, the patient’s corneal reflexes as well as pupillary and gag reflexes are present. Coma means that the patient has a much lower level of consciousness and loses awareness of the surroundings as well as the self, but the patient can have a simple or mild response to a strong stimulus, when the patient’s corneal reflex is diminished and the gag reflex and reflex to light are present. Coma means that the patient loses consciousness completely and does not respond to external stimuli. At this time, the patient’s swallowing, corneal, and even light reflexes are non-existent and disappear.