Benign fasciculation synrome (BFS) is a neurological disorder characterized by fasciculation (twitching) of various voluntary muscles in the body. The twitching can occur in any voluntary muscle group but is most common in the eyelids, arms, legs, and feet. Even the tongue may be affected. The twitching may be occasional or may go on nearly continuously. Any intentional movement of the involved muscle causes the fasciculations to cease immediately, but they may return once the muscle is at rest again.