MRI measurements of brainstem structures in patients with Richardson's syndrome, progressive supranuclear palsy‐parkinsonism, and Parkinson's disease

We investigated the diagnostic accuracy of brainstem MRI measurements in patients with different progressive supranuclear palsy (PSP) syndromes and Parkinson's disease (PD). Using 3D T1-weighted images, midbrain, and pons areas, as well as superior (SCP) and middle cerebellar peduncle (MCP) widths were measured in 10 patients with Richardson's syndrome (PSP-RS), 10 patients with PSP-parkinsonism (PSP-P), 25 patients with PD, and 24 healthy controls. The ratio between pons and midbrain areas (pons/midbrain), that between MCP and SCP widths (MCP/SCP), and the MR parkinsonism index ([pons/midbrain]*[MCP/SCP]) were calculated. 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 experience a relatively less severe involvement of infratentorial brain. The pons/midbrain looks as a promising measure in the differentiation of individual PSP-P from PD patients.