'Hummingbird and Morning Glory' of Radiology

Progressive Supranuclear Palsy (PSP) (Syn : Steele-Richardson-Olszewski Syndrome)

• Adult onset neurodegenerative disorder. Taupathy.
• Characterized by early postural instability leading to backward falls within the first year, abnormal eye movements due to supranuclear vertical gaze palsy and abnormal cognition.
• Important to distinguish PSP from Parkinsons Disease and and others like MSA as levodopa is less or no efficacious in treatment in PSP.
• PSP shows marked dorsal midbrain atrophy, with reduction in AP diameter.
• MRI describes few signs in Progressive Supranuclear Palsy namely the Hummingbird sign (aka Penguin Sign), Morning Glory Sign. 
• Reduction in the ratio of areas of Midbrain and Pons is described in PSP.
• Other signs include widening of the Inter Peduncular Cistern and Reduced AP distance of the midbrain at the level of superior colliculus from the interpeduncular fossa to the intercollicular groove (<12mm).
• Increased T2 signal of midbrain and olives, atrophy  and increased signal intensity of superior cerebellar peduncles are also seen.
• Bilateral putamina can show hypointense signal intensity due to increased iron content.
• Associated frontal and parietal atrophy are also seen. Third ventricle is usually dilated.

Above image shows the method of assessing for Morning Glory sign.

Again a normal patient with convex lateral margin of tegmentum.

Above image showing the concave lateral margin of tegmentum, termed as the Morning Glory Sign, which has been stated as a more specific sign of Progressive Supranuclear palsy.

Above images shows the comparison with a normal midbrain showing the superior convex contour and that of an atrophic midbrain showing concave superior contour in a Progressive Supranuclear Palsy patient. The appearance is likened to that of a Humming Bird.

Note : In the original article, the Morning glory sign, is described as the authors saw a likeness of atrophied midbrain to the lateral view of morning glory flower.

References :
1. Magn Reson Med Sci. 2004 Dec 15;3(3):125-32. Morning glory sign: a particular MR finding in progressive supranuclear palsy. Adachi M(1), Kawanami T, Ohshima H, Sugai Y, Hosoya T.
2. CT and MRI of the Whole Body, 6th Edition, John.R.Haaga, Elsevier Publications.
3. Humming bird and Morning glory images from pixabay.com , under CC0.