Differentiation of atypical parkinsonian syndromes and their separation from idiopathic Parkinson's disease by means of routine magnetic resonance imaging

Atrophy of frontal lobe, midbrain, pons, and cerebellum was studied in 16 patients with progressive supranuclear palsy (PSP), 14 with multiple system atrophy of striatonigral type (MSA-P),20 with idiopathic Parkinson's disease (IPS),and 12 age-matched healthy controls using axial T2-weighted MR images (1.5 Teslar). With < 16 mm, the PSP group showed significantly lower anteroposterior midbrain diameters than the IPS, MSA-P, and control groups. We conclude that measurement of the anteroposterior diameter of the midbrain with axial T2-weighted MRI is a useful feature and should be incorporated into the diagnostic criteria for PSP. In addition to the typical slit hyperintensity in margin of putamen and decreased signal intensity in dorsolateral putamen,we found cerebellar atrophy in 64% of patients with MSA-P. Before now, this was considered a typical sign of multiple system atrophy of cerebellar type (MSA-C). The use of this feature in the differential diagnosis of both types of multiple system atrophy is debatable.