Morphological in vivo investigation of two main variants of progressive supranuclear palsy

Abstract

Progressive supranuclear palsy (PSP) can occur with two main clinical presentations, classified as classical Richardson’s syndrome (PSP-RS) and as PSP-parkinsonism (PSP-P), the most common atypical PSP variant. The differential diagnosis between them is challenging, as well as from idiopathic Parkinson’s disease (PD). Therefore, we studied different neuroimaging markers, using both conventional and unconventional MRI methods to test their value in the diagnostic work up of PSP and PD patients. Ten PSP-RS, 10 PSP-P, 25 PD patients, and 24 healthy controls were studied. Neuroimiging investigations included MRI brainstem region of interest measurements, as well as voxel-based morphometry (VBM) analysis. The pons/midbrain and the MR parkinsonism index allowed to differentiate PSP-RS from PD with high sensitivity (90%, 100%), specificity (96%, 92%), and accuracy (94%, 97%). Only the pons/midbrain was found to distinguish PSP-P from PD, but with a lower diagnostic accuracy (sensitivity = 60%, specificity = 96%, accuracy = 86%). Compared to PSP-RS, PSP-P experienced a different pattern of both gray matter and white matter atrophy on VBM. Compared to PSP-RS, PSP-P experience a relatively less severe atrophy of infratentorial brain. The pons/midbrain looks as a promising measure in the differentiation of individual PSP-P from PD patients.