Progressive Supranuclear Palsy (PSP) is frequently misdiagnosed as Parkinson disease (PD), particularly in the early stages. However, PSP and PD differ in several respects. PSP is less common than PD, the tremor in PSP is typically less conspicuous than that seen in PD, and the facial expression of PSP is usually described as "grimacing" rather than the "masked" face of PD. The rigidity of PSP affects the neck most prominently, causing an erect posture rather than the stooped posture of PD. Eye movement disorders (especially of downward gaze) are more prominent in PSP.

Cognitive problems also appear to be part of the clinical picture of PSP. Speed of mental processing is slowed and deficits in memory, attention, and problem solving have been reported. The cognitive problems tend to be more severe in PSP than PD.

The neuropathology of PSP overlaps with that of PD, but important differences have been noted. Degeneration occurs in a number of brainstem nuclei, including the periaqueductal grey matter, subthalamic nucleus, substantia nigra, globus pallidus, caudate, and putamen. Neurofibrillary tangles, rather than the Lewy bodies of PD, are typically found. There also appears to be a greater loss of dopamine in the caudate than the putamen, the reverse of what is normally found in PD.

Treatment of PSP is much less effective than treatment of PD. Dopamine agonists and levadopa have been use, but with only marginal success. Anti-depressant medication may be of some benefit in improving overall mood.

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