BACKGROUND: Diagnostic dilemma between clinical Meniere\'s disease and radiological endolymphatic hydrops (EH) has emerged since the introduction of hydrops magnetic resonance imaging (MRI). The aim of this study is to explore the potential application of hydrops MRI on diagnosing the EH.
METHODS: This review was developed from peer-reviewed articles published in those journals listed on journal of citation reports. The MEDLINE database of the US National Library of Medicine, Scopus, and Google Scholar were used to collect articles based on the guidelines (PRISMA 2020 statement) for reporting reviews.
RESULTS: Initially, 470 articles were retrieved from 1983 to 2023, and 80 relevant articles were ultimately selected. The sensitivity (69%-92%) and specificity (78%-96%) values varied from each laboratory for detecting EH via hydrops MRI, probably due to candidate selection and the grading system employed.
CONCLUSIONS: The application of hydrops MRI allows (1) differentiation between EH and sudden sensorineural hearing loss; (2) determination of the affected side of EH; and (3) confirmation of the diagnosis of EH concomitant with other disorders. Notably, not all differentials for EH can be visualized on MR images. One of the existing gaps to be filled is that updated hydrops MRI fails to identify distortion, that is, rupture, collapse, fistula, or fibrosis of the inner ear compartments, akin to what histopathological evidence can demonstrate. Hence, enhanced ultrahigh resolution of hydrops MRI is required for demonstrating fine structures of the inner ear compartments in the future.

OBJECTIVE: This study utilized the recently advanced technique in MR imaging to establish its role on diagnosing all types of endolymphatic hydrops (EH).
METHODS: Twenty-two patients (26 ears) with clinical EH were admitted due to acute hearing loss and/or vertiginous attack. Each patient underwent an inner ear test battery comprising audiometry, cervical and ocular vestibular-evoked myogenic potential tests, and caloric test, followed by MR imaging for confirmation.
RESULTS: Of the 22 clinical EH patients, 12 patients were referred to primary EH (Meniere\'s disease), 8 patients were secondary EH (including delayed EH in 5), and 2 patients were EH of embryopathic origin. MR imaging of 26 affected ears demonstrated EH in the cochlea only for 14 ears, in the utricle and saccule only for 1 ear, and in all three endorgans for 3 ears, accounting for a sensitivity of 69% (18/26). The 8 affected ears showing negative MR images were EH patients with hearing recovery 1, just after vertiginous attack 3, and chronic low-tone hearing loss 4. In contrast, 3 out of 18 unaffected ears demonstrated asymptomatic EH in the cochlea, representing a specificity of 83% (15/18).
CONCLUSIONS: The sensitivity and specificity of MR imaging for confirming all types of EH were 69% and 83%, respectively. Although diagnostic criteria can identify primary and delayed EH, MR imaging may provide a supplementary tool for diagnosing secondary, embryopathic, or asymptomatic EH, if patients are not with hearing recovery, chronic low-tone hearing loss, or just after vertiginous attack.

Background: Elder Meniere\'s disease (MD) patients ultimately lose their vestibular function. Objective: This study utilized an inner ear test battery to investigate evolution of MD. Methods: Total 278 elder MD patients aged >65 years were divided into three groups. Ninety-four patients with bilateral MD (188 ears) were assigned to Group A. The remaining 184 patients with unilateral MD were further divided into two groups. Group B consisted of 20 affected ears with normal vestibular function on the opposite ears, while Group C indicated 184 unaffected ears. All patients underwent an inner ear test battery. Results: Inner ear deficits in Group B declined from the cochlea via the saccule, utricle to semicircular canals. In contrast, Groups A and C did not significantly differ in the abnormality rates of cervical vestibular-evoked myogenic potential (cVEMP), ocular VEMP and caloric tests, indicating that Group C (unaffected ears) may partly share the same mechanism like Group A (affected ears), namely aging and hydropic effects. Conclusion and significance: Evolution of MD may progress from unilateral MD (MD 1.0), via unilateral MD coupled with asymptomatic hydrops on opposite ear (MD 1.5), toward bilateral MD (MD 2.0), where the number 1.0-2.0 means the number of clinically affected ears.