Presentation
History of gait instability with parkinsonian features, unresponsive to levodopa.
Patient Data
Age: 75 years
Gender: Male
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There was significant atrophy of the midbrain with a "hummingbird" or "penguin" sign on sagittal images due to preserved pontine volume.
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The corresponding axial images reveal a concave dorso-lateral midbrain margin (yellow) which is normally convex. there is a deep interpeduncular cistern as well (red)