Facial muscle spasm, also known as facial muscle twitching, is characterized by episodic, rhythmic involuntary twitching of one side of the facial muscles. Facial myoclonus is difficult to heal on its own once it has developed. The initial symptoms are mostly intermittent twitching of the upper or lower eyelid on one side, which usually does not attract attention. The twitching will gradually worsen over time, expanding to the corners of the mouth and even to the neck. The duration of the twitching extends from a few seconds at the beginning to several minutes or even longer. In severe cases, the muscles are tense and the eyes cannot be opened and the corners of the mouth are distorted. Most patients continue to have twitching episodes during sleep, and some may be unable to sleep due to the intensity of the twitches. Patients feel distracted and disturbed, which greatly affects normal work, study and life until it becomes unbearable.