Patterns of brain atrophy that differentiate corticobasal degeneration syndrome from progressive supranuclear palsy

Background: Progressive brain atrophy is associated with the corticobasal degeneration syndrome (CBDS) and progressive supranuclear palsy (PSP). Regional differences in brain atrophy may reflect the clinical features of disease. Objective: To quantify the structural neuroanatomical differences between CBDS and PSP. Design: A survey of neurologic deficits was conducted in all patients. Voxel-based morphometry was used to quantify structural neuroanatomical differences on magnetic resonance images in each subject group. Setting: University hospital dementia clinic. Participants: Fourteen patients who met clinical research criteria for CBD and 15 patients who met clinical research criteria for PSP, who were matched for severity of disease, age, and functional status, and 80 age-matched control subjects. Main Outcome Measures: Statistically significant differences in regional gray and white matter volume, after multiple comparisons correction, between groups of subjects. Results: The patients with CBDS displayed an asymmetric (left > right) pattern of brain atrophy that involved the bilateral premotor cortex, superior parietal lobules, and striatum. Progressive supranuclear palsy was associated with atrophy of the midbrain, pons, thalamus, and striatum, with minimal involvement of the frontal cortex. Midbrain structures were more atrophied in PSP than in CBD, whereas dorsal frontal and parietal cortices were more atrophied in CBD than in PSP. The degree of atrophy of the midbrain and pontine tegmentum and the left frontal eye field differentiated the 2 patient groups with 93% accuracy. Conclusions: Distinct patterns of brain atrophy exist in CBDS and PSP that can be used to differentiate the 2 diseases. Assessments of brain atrophy in these disorders should be focused on cortical and brainstem ocular motor control areas.