Objective: To identify cognitive and MRI features important for the clinical diagnosis of corticobasal degeneration (CBD) and progressive supranuclear palsy (PSP); these diseases share several clinical features and are often difficult to distinguish on clinical grounds.
Methods: Cognitive functions and MRI characteristics were examined in 16 patients with CBD and 28 patients with PSP, all diagnosed according to current clinical criteria (none was examined by autopsy).
Results: MRI findings differed significantly between the two groups: 87.5% of patients with CBD but none with PSP had asymmetric frontoparietal atrophy, whereas 89.3% of patients with PSP but only 6.3% of those with CBD had midbrain atrophy. Cognitive examination showed that ideomotor apraxia (De Renzi's test) was significantly more frequent in CBD, and executive functions (Nelson's test) were significantly more impaired in patients with PSP.
Conclusions: MRI findings of asymmetric frontoparietal atrophy in CBD and midbrain atrophy in PSP are the most consistent and useful aids to careful clinical evaluation for differentiating between the two diseases.