Fig. 1

a 3D real inversion recovery sequence MRI showing a mild cochlear EH (white arrow) and a significant vestibular EH (red arrow) in the right ear and there is no pathological finding in the left ear. b The external aperture of the VA can be well visualized in the Pöschl plane. When failing to visualize this structure, non-visualization of the VA was recorded. In this image, JB was classified as type 1 because of no bulb. c The external aperture of the VA can also be well visualized in the Pöschl plane. In this image, JB was classified as type 2 because of the JB below the inferior margin of the PSCC. d Anteroposterior (black line) and mediolateral (white line) diameters of the JB were recorded on the axial image at the level where the foramen spinosum (arrow) could be observed. e The height of the JB was recorded by measuring the distance between the level of the JB dome and the line passing through the confluence of the sigmoid sinus with the JB on the coronal image. The JBVAD was defined as when the bony coverage separating the JB and VA is dehiscent. The JBD was defined as when a prominent protrusion or outpouching of the JB can be clearly distinguished from a smooth ellipsoidal form on the coronal image. EH, endolymphatic hydrops; JB, jugular bulb; JBD, JB diverticulum; JBVAD, JB-vestibular aqueduct dehiscence; H, height; AP, anteroposterior; ML, mediolateral; PSCC, posterior semicircular canal; VA, vestibular aqueduct