Hummingbird sign (midbrain)

Last revised by Assoc Prof Frank Gaillard on 23 Feb 2022

The hummingbird sign, also known as the penguin sign, refers to the appearance of the brainstem in patients with progressive supranuclear palsy (PSP)

The atrophy of the midbrain results in a profile of the brainstem (in the sagittal plane) in which the preserved pons forms the body of the bird, and the atrophic midbrain the head, with beak extending anteriorly towards the optic chiasm. Midbrain atrophy is best confirmed with reduction in the midbrain to pons ratio.

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Cases and figures

  • Hummingbird (photo)
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  • Case 1
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  • Case 2
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  • Case 3
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  • Case 4
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  • Case 5
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  • Case 6
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