The <i>in vivo</i> distribution of brain tissue loss in Richardson’s syndrome and PSP‐parkinsonism: a VBM‐DARTEL study

In this study, we wished to test, using magnetic resonance imaging and voxel-based morphometry (VBM), whether specific cortical and subcortical patterns of brain grey (GM) and white matter (WM) tissue loss can be detected in patients with Richardson's syndrome (PSP-RS) and progressive supranuclear palsy-parkinsonism (PSP-P), and possibly account for their clinical heterogeneity. Twenty patients with PSP, classified as PSP-RS (10 patients) or PSP-P (10 patients), and 24 healthy controls were studied. The Statistical Parametric Mapping (SPM5) and the Diffeomorphic Anatomical Registration using Exponentiated Lie algebra method were used to perform a VBM analysis. Compared with controls, both patient groups showed GM loss in the central midbrain, cerebellar lobes, caudate nuclei, frontotemporal cortices and right hippocampus. WM loss was detected in both conditions in the midbrain, left superior cerebellar peduncle, internal capsulae, and left premotor and bilateral prefrontal regions. Compared with PSP-P, patients with PSP-RS showed additional regions of GM loss in the midbrain, left cerebellar lobe and dentate nuclei. PSP-RS was also associated with a more severe WM loss in the midbrain, internal capsulae, and orbitofrontal, prefrontal and precentral/premotor regions, bilaterally. Patients with PSP-P showed a more pronounced GM loss only in the frontal cortex, bilaterally. This study shows that, albeit the overall pattern of brain atrophy associated with PSP appears remarkably consistent across the spectrum of clinical features recorded in life, major anatomical differences between these two conditions do exist. Such a different topographical distribution of tissue damage may account for the clinical differences between PSP-RS and PSP-P.