Section Editor: Sandy Cheng-Yu Chen, M.D.
Taipei Medical University Hospital, Taipei, Taiwan
Figure Caption
Progressive supranuclear palsy (PSP) is a neurodegenerative disorder characterized by supranuclear vertical gaze palsy, postural instability, and Parkinsonian features. The classic imaging findings of PSP are midbrain and superior cerebellar peduncle atrophy, which can be differentiated from multiple system atrophy, where the structures that are mainly involved are the middle cerebellar peduncles and cerebellum. All of these brain structures are spared in Parkinson disease. In PSP, the penguin silhouette sign/humming bird sign (atrophy of the midbrain tegmentum and the normal pons) is suggestive of marked midbrain atrophy (A). There is thinning of the superior colliculus (arrow in A) and the superior cerebellar peduncles (arrows in B), and loss of the normal convexity of the superior midbrain tegmentum (morning glory sign; arrows in C).