Below is an instruction from Human. Write a response.
    ### Instruction:
    What is (are) rapid-onset dystonia parkinsonism ?
    ### Response:
    Rapid-onset dystonia parkinsonism is a rare movement disorder. "Rapid-onset" refers to the abrupt appearance of signs and symptoms over a period of hours to days. Dystonia is a condition characterized by involuntary, sustained muscle contractions. Parkinsonism can include tremors, unusually slow movement (bradykinesia), rigidity, an inability to hold the body upright and balanced (postural instability), and a shuffling walk that can cause recurrent falls.
    