ABSTRACT
BACKGROUND In Parkinson’s disease (PD), the occurrence of dyskinesias represents interplay between disease and treatment. Dyskinesias can be defined as involuntary, patterned movements affecting any part of the body. They often have a torsional or fidgeting quality. The term chorea pertains to the dancing-like quality of these involuntary movements, while athetosis refers to twisting movements along the axis of a limb. Sustained and abnormal postures characterize dystonia. Dyskinesia is a more general term that can describe each of these and sometimes more unusual types of motions, as will be discussed below. PD’s primary identity is that of diminished speed and dexterity of volitional movements. In PD, the only involuntary movements encountered in the unmedicated disorder are tremor (usually occurring at rest or with position maintenance), and dystonic posturing (especially equinovarus positions of the feet). Sometimes PD patients experience an internal sense of tremor and can respond to restless feelings by carrying out stereotyped movements such as pacing or rocking the legs. The movements made
in response to such sensations (akathisia) can be suppressed, since they are voluntary in origin.
