No, they do not mean the same thing. In chorea, the movements involve distal muscles, as opposed to hemiballismus, which involve proximal muscles. In both conditions the purposeless movements are brisk, random (in both timing and distribution) and basically continuous. The main difference is that chorea is often bilateral, hemiballismus is unilateral. In chorea, the movements are often incorporated into voluntary movements, so that a movement of the arm can become a scratching behind the ear. Also, voluntary movements cannot be sustained e.g. there is a fluctuation in grip known as ‘milkmaid’s grip’.
On the other hand, dystonia consists of abnormal fixed postures which may be prolonged or fleeting as a result of sustained muscle contractions. Any group of muscles in the body may be affected. If only one body part is affected, such as the arm or neck, the dystonia is focal. If a contiguous region of the body is involved, such as one arm and the trunk, it is called segmental, and if the whole body is involved, it is generalized. Some movements are involuntary, others arise as excessive, unwanted concomitants to voluntary movements.
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