Clinicopathological aspects of motor parkinsonism.

Motor parkinsonism is characterised by bradykinesia, muscle rigidity, postural instability and resting tremor that occur most often in Parkinson's disease, multiple system atrophy and progressive supranuclear palsy. In all three disorders the main regulators of the caudate nucleus and putamen (dopaminergic substantia nigra and glutaminergic caudal intralaminar nuclei), as well as the cortical projection from the presupplementary motor area, degenerate. Degeneration of the major basal ganglia circuit neurons also occurs in multiple system atrophy, while degeneration of the subthalamus and a widespread loss of inhibitory interneurons within the extrapyramidal system occurs in progressive supranuclear palsy.