The Hummingbird Sign

Abstract

Progressive supranuclear palsy also known as Steele-Richardson syndrome (PSP-RS) is a neurodegenerative disease that manifests as axial rigidity, unstable posture, and supranuclear gaze palsy. Thus, there is a marked atrophy of the middle of the brain involving midbrain. The MRI will show on the median sagittal slices weighted in T1 the sign of the Humming-bird or the sign of the Penguin (Figure 1) which describes the flat or concave aspect of the mesencephalic tegmentum. This sign, which recalls the appearance of the beak of the Hummingbird Bird or the beak of the Penguin (Figure 2), is typical of PSP-RS, with a specificity of 99.5% [1]. This sign is often associated with the Morning Glory Sign which has a specificity of 97.7%, observed on axial slices weighted of the MRI, corresponding to the concave aspect of the lateral margin of the Tegmentum of the midbrain [2]. Those appearance reflect a reduction in the anteroposterior diameter of the mesencephalon testifying to its atrophy [1,2].