Dystonia: Involuntary movements and prolonged muscle contraction that result in twisting body motions, tremors, and abnormal posture. These movements may involve the entire body or only an isolated area. Dystonia can be inherited, may occur sporadically without any genetic pattern, may be associated with medications (particularly antipsychotic drugs), or may be a symptom of certain diseases (for example, a specific form of lung cancer). Some types of dystonia respond to dopamine. Dystonia can sometimes also be controlled with sedative-type medications or surgery.