Torticollis: The most common of the focal dystonias, a state of excessive or inadequate muscle tone in the muscles in the neck that control the position of the head. Torticollis can cause the head to twist and turn to one side. The head may also be pulled forward or backward. Torticollis can occur at any age, although most individuals first experience symptoms in middle age. It often begins slowly, and it usually reaches a plateau. Also known as spasmodic torticollis.