Transtorno de movimento estereotipado is characterised by the persistent (e.g., lasting several months) presence of voluntary, repetitive, stereotyped, apparently purposeless (and often rhythmic) movements that arise during the early developmental period, are not caused by the direct physiological effects of a substance or medication (including abstinência), and markedly interfere com normal activities or result in self-inflicted bodily injury. Stereotyped movements that are non-injurious can include body rocking, head rocking, finger-flicking mannerisms, and hand flapping. Stereotyped self-injurious behaviours can include repetitive head banging, face slapping, eye poking, and biting of the hands, lips, or other body parts.