Image diagnosis of endolymphatic hydrops

Abstract

　　The characteristic symptoms of Meniere's disease are recurrent vertigo, fluctuating hearing loss and tinnitus, and the principal underlying pathology is endolymphatic hydrops (ELH). Imaging of endolymphatic hydrops is now possible by 3-Tesla MRI after intratympanic (IT) or intravenous injection (IV) of gadolinium (Gd). 3D-FLAIR and 3D-real IR are obtained in the case of IT injection of contrast, while heavily T2-weighted 3D-FLAIR and HYbriD of Reversed image Of Positive endolymph Signal and native image of positive perilymph signal (HYDROPS) are obtained in the case of IV injection of contrast, to visualize the endolymphatic space. Higher concentrations of the contrast agent can be introduced into the perilymph by IT injection than by IV injection. However, the IV method is preferable in the clinical setting, as the endolymphatic spaces of both ears can be evaluated after a single intravenous injection of Gd. ELH is observed more frequently in patients with definite Meniere's disease than in those with possible Meniere's disease. ELH is observed in both the cochlea and the vestibule in patients with atypical Meniere's disease. The vestibular Meniere's disease patients show significant vestibular predominance in the distribution of ELH. ELH is observed more frequently in patients with fluctuating tinnitus than in patients with stable tinnitus. Examination of ELH can be performed as part of preoperative evaluation prior to stapes surgery in patients with otosclerosis; the presence of ELH is a risk factor for the development of severe vertigo after stapes surgery. Examination to detect vestibular ELH can be helpful in the differential diagnosis between vestibular migraine and vestibular Meniere's disease. MRI is a sensitive technique for detecting ELH and the relationships between ELH and clinical symptoms are expected to be widely investigated using this technique.