Periodic limb movement disorder refers to periodic recurrent limb movements during sleep, which are repetitive leg twitches, toes, ankles, and dorsiflexion-like twitches of episodic nature, such as each episode lasting about 0.5-10 seconds, followed by another one after an interval of 5 seconds or 90 seconds. The occurrence of ≥4 twitches at night is called one periodic limb movement disorder. This condition is mostly caused by contraction of the anterior cervical muscles and is mainly seen in cases of organic diseases of the nervous system.