E2408. A Primer on MR Imaging of Meniere’s Disease and Endolymphatic Hydrops
  1. Christopher Yu; University of California, Los Angeles
  2. Luke Ledbetter; University of California, Los Angeles
Meniere’s disease is an inner ear disorder characterized by vertigo, tinnitus and sensorineural hearing loss. Although the pathophysiology is not known, endolymphatic hydrops (EH), or the abnormal accumulation of endolymphatic fluid within the inner ear, is a hallmark of the disease. Previously, postmortem histologic analysis was required to validate the presence of EH. Although indirect tests exist to infer the presence of EH, these have largely been insensitive. In the last decade, MRI techniques with gadolinium-based contrast have emerged as a method to directly visualize EH in living patients.

Educational Goals / Teaching Points
Review Meniere’s disease and the relevant inner ear anatomy. Diagram the MRI methods that allow delineation of inner ear compartments and evaluation for EH and present cases of Meniere’s disease with various appearances of EH. Diagrams will complement MR images to aid understanding of the pathology. Discuss the clinical implications of imaging EH for Meniere’s disease. Show cases and review inner ear diseases that clinically and radiographically mimic Meniere’s and/or produce EH.

Key Anatomic/Physiologic Issues and Imaging Findings/Techniques
The inner ear comprises the cochlea, vestibule, and semicircular canals. These structures are separated into the endolymphatic and perilymphatic spaces. In general, EH is present when the endolymphatic space becomes larger than normal compared to the perilymphatic space. Gadolinium-based contrast agents accumulate in the perilymphatic space, and when imaged with heavily T2-weighted sequences with different inversion times, the endolymphatic and perilymphatic spaces can be differentiated. However, as the inner ear is a small and complex structure, post-processing is employed to improve visualization and assessment of EH. On imaging, the cochlea and vestibule are evaluated separately for EH, since Meniere’s may initially present with only cochlear or vestibular symptoms before developing both. Thus, Meniere’s disease is often difficult to clinically diagnose and remains a diagnosis of exclusion. MRI for EH may be helpful in these unclear situations, as some studies suggest a sensitivity of 90 - 95% for Meniere’s disease, and to exclude other etiologies. Some have suggested early EH detection may guide early treatment, analogous to treating elevated intraocular pressures to prevent glaucoma in asymptomatic individuals, however, this requires further study.

This exhibit aims to be a primer for radiologists to understand the role of MRI of endolymphatic hydrops for Meniere's disease.