Stereotypic movement disorder
（重定向自Habit disorder）
Stereotypic movement disorder (SMD) is a motor disorder with onset in childhood involving repetitive, nonfunctional motor behavior (e.g., hand waving or head banging), that markedly interferes with normal activities or results in bodily injury. The behavior must not be due to the direct effects of a substance or another medical condition. The cause of this disorder is not known.