Pathologic changes of progressive supranuclear palsy, corticobasal degeneration, and multiple system atrophyPrototype and clinicopathological diversity

Progressive supranuclear palsy (PSP), corticobasal degeneration (CBD), and multiple system atrophy (MSA) are manifested as atypical parkinsonism. Both PSP and CBD are considered tauopathies because of the accumulation of tau protein in the brains, and MSA is considered a synucleinopathy owing to accumulation of α-synuclein. Although some pathological changes are found in both PSP and CBD, other changes allow the two conditions to be differentiated. Typical clinical manifestations of PSP and CBD have been described, but unusual clinical manifestations, which complicate clinical diagnosis, have been reported. MSA has been divided into the pathological subtypes of striatonigral degeneration and olivopontocerebellar atrophy, although some cases of MSA have features of both subtypes. Both the substantia nigra and the putamen are initially affected in the striatonigral degeneration subtype. Rare patients have both MSA and PSP.