Inferior part of the vestibulum and correlated axial cryosections

Cropped axial delayed gadolinium-enhanced 3D FLAIR images at the inferior part of the vestibulum and correlated axial cryosections with hematoxylin and eosin staining (magnification, × 7) and color overlay. (a) Normal vestibule (grade 0). The saccule (small arrowhead) and utricle (large arrowhead) are visibly separate and take less than half of the surface of the vestibule. (b) Vestibular hydrops grade I: The saccule (small arrowhead), normally the smallest of the two vestibular sacs, has become equal or larger than the utricle (large arrowhead) but is not yet confluent with the utricle. (c) Vestibular hydrops grade 2: There is a confluence of the saccule and utricle (arrowhead) with still a peripheral rim enhancement of the perilymphatic space (arrow). (d) Vestibular hydrops grade 3: The perilymphatic enhancement is no longer visible (arrowhead). There is a full obliteration of the bony vestibule. Also notice in this case, the beginning utricular protrusion in the non-ampullated part of the lateral (horizontal) semicircular canal (arrow). (Source: Bernaerts A, Vanspauwen R, Blaivie C, et al. The value of four-stage vestibular hydrops grading and asymmetric perilymphatic enhancement in the diagnosis of Menière's disease on MRI. Neuroradiology 2019;61[4]:421-429. Creative Commons Attribution 4.0 International [CC BY 4.0] license, creativecommons.org/licenses/by/4.0.)