Figure 1. Structural MRI demonstrating the morphological characteristics of PSP-RS and brainstem measurements.
Top left sagittal slice shows the hummingbird sign with atrophy of the dorsal midbrain and relative preservation of the pons. Top right axial slice through the midbrain shows rounded midbrain peduncles (Mickey Mouse sign) and concavity of the lateral margin of the midbrain tegmentum (Morning glory sign, arrow). Bottom images show example measurements of the midbrain anteroposterior (AP) diameter, midbrain and pons area, superior cerebellar peduncle width and middle cerebellar peduncle width (modified from32).