A neurological condition related to lesions of the basal ganglia leading to typical abnormalities including akinesia (inability to initiate changes in activity and perform volitional movements rapidly and easily), muscular rigidity (continuous contraction of muscles with constant resistance to passive movement), chorea (widespread arrhythmic movements of a forcible, rapid, jerky, and restless nature), athetosis (inability to sustain the muscles of the fingers, toes, or other group of muscles in a fixed position), and akathisia (inability to remain motionless).
Comment:
The basal ganglia, paired subcortical masses of gray matter that form distinct nuclei, subserve motor functions that are distinct from those of the pyramidal (i.e., corticospinal) tract. This is a bundled term that is kept for historical reasons, but it is preferable to annotate the precise abnormalities observed.