Magnetic resonance imaging-based volumetry differentiates idiopathic Parkinson's syndrome from multiple system atrophy and progressive supranuclear palsy

By using three-dimensional magnetic resonance imaging-based volumetry, we s tudied atrophy of the caudate nucleus, putamen, brainstem, and cerebellum i n patients with idiopathic Parkinson's syndrome (IPS, n = 11), progressive supranuclear palsy (PSP, n = 6), and multiple system atrophy with predomina nt parkinsonism (MSA-P, n = 12) or ataxia (MSA-C, n = 17). Patients were co mpared with a total of 46 controls, of whom 16 were age matched Mean striat al, cerebellar, and brainstem volumes were normal in patients with IFS. We found significant reductions in mean striatal and brainstem volumes in pati ents with MSA-P, MSA-C, and PSP, whereas patients with MSA-C and MSA-P also showed a reduction in cerebellar volume. On an individual basis, volumes o f structures in patients with MSA and PSP showed an extensive overlap with the normal range with the exception of brainstem volumes in patients with M SA-C. Therefore, groups could not be discriminated on the basis of individu al structure volumetry. Application of stepwise discriminant analysis, howe ver, allowed discrimination of all 12 patients with MSA-P, 15 of 17 patient s with MSA-C, arid 5 of 6 patients with PSP from the normal and IFS cohorts . However, patients with LPS could not be separated from controls and patie nts with MSA-P could not be separated from patients with PSP. In conclusion , total intracranial volume-normalized magnetic resonance imaging-based vol umetric measurements provide a sensitive marker to discriminate typical and atypical parkinsonism.