Morphological correlation between caloric tests and vestibular hydrops in Ménière's disease using intravenous Gd enhanced inner ear MRI.

Ji Eun Choi,Hyung-Jin Kim,Won-Ho Chung,Kieun Lee,Sung Hoon Yoon,Hyun Woo Park,Young Sang Cho,Yi-Kyung Kim,Manabu Sakakibara

doi:10.1371/journal.pone.0188301

Abstract

The purpose of this study was to prove the hypothesis that caloric response in Ménière's disease (MD) is reduced by hydropic expansion of the vestibular labyrinth, not by vestibular hypofunction, by evaluating the correlation morphologically using an intravenous Gadolinium (IV-Gd) inner ear MRI. In study I, the prevalence of abnormal video Head Impulse Test (vHIT) results among the patients with definite unilateral MD (n = 24) and vestibular neuritis (VN) (n = 22) were investigated. All patients showed abnormal canal paresis (CP) (> 26%) on caloric tests. The prevalence of abnormal vHIT in patients with abnormal CP was significantly lower in MD patients (12.5%) than that in VN patients (81.8%) (p < 0.001). In study II, morphological correlation between caloric tests and vestibular hydrops level was evaluated in unilateral MD patients (n = 16) who had normal vHIT results. Eleven patients (61%) had abnormal CP. After taking the images of IV-Gd inner ear MRI, the vestibular hydrops ratio (endolymph volume/total lymph volume = %VH) was measured. In addition, the relative vestibular hydrops ratio (%RVH = (%VHaffected ear—%VHunaffected ear) / (%VHaffected ear + %VHunaffected ear)) was calculated. Each ratio (%VH and %RVH) was compared with average peak slow phase velocity (PSPV) and CP, respectively. In the MD patients, %VH of the affected ear correlated significantly with mean PSPV on the same side (rs = -0.569, p = 0.024), while %RVH correlated significantly with CP (rs = 0.602, p = 0.014). In most MD patients (87.5%) compared to VN patients, vHIT results were normal even though the caloric function was reduced. In addition, the reduced caloric function with normal vHIT was related to the severity of the vestibular hydrops measured by the IV-Gd inner ear MRI. These findings concluded that the abnormal caloric tests with normal vHIT in MD indicated severe endolymphatic hydrops rather than vestibular hypofunction.

Highlights

Menière’s disease (MD) is an idiopathic inner ear disorder with symptom complex of recurrent vertigo, hearing loss, tinnitus, and ear fullness
The prevalence of abnormal video head impulse test (vHIT) results was significantly lower in patients with MD (3/24 = 12.5%) compared to that in patients with vestibular neuritis (VN) (18/22 = 81.8%) (p < 0.001, Chi-square analysis)
In Study I, we found that even though the caloric function was reduced, the high frequency vestibule-ocular reflex (VOR) function revealed by vHIT was preserved in most patients with MD (87.5%)

Summary

Introduction

Menière’s disease (MD) is an idiopathic inner ear disorder with symptom complex of recurrent vertigo, hearing loss, tinnitus, and ear fullness. The natural course of MD varies highly, most patients suffer repeated vertigo attacks and gradually lose their hearing and vestibular function [1]. The endolymphatic hydrops is currently known as a histologic hallmark of MD, but the causes of MD are unknown [2]. Bithermal water irrigation into the external ear canal causes the convective current in the endolymph of the horizontal semicircular canal (HSCC) to induce the cupular deflection [3]. Resulting peak slow phase eye velocity (PSPV) was measured and canal paresis (CP) was calculated by comparing PSPV from both sides which indicates the function of vestibule-ocular reflex (VOR) at low frequency (0.002–0.004 Hz). In about half the cases of unilateral MD, canal paresis (CP) on the affected side was reported [4,5]

Objectives

Methods

Results

Conclusion