The value of post-contrast delayed three-dimensional fluid-attenuated inversion recovery MRI in the diagnosis of unilateral vestibulopathy manifesting as episodic vestibular syndrome.

Background: Unilateral vestibulopathy (UVP) manifesting as episodic vestibular syndrome (EVS) is quite common in clinical practice. In recent years, post-contrast delayed three-dimensional fluid-attenuated inversion recovery (3D-FLAIR) magnetic resonance imaging (MRI) has drawn increasing attention from clinicians owing to its effects in identifying the lesion site and speculating the possible mechanisms of UVP. This study aimed to investigate 3D-FLAIR MRI findings in patients with UVP manifesting as EVS, analyze their correlations with cochleovestibular function test results, determine the predictive factors for abnormal MRI findings in such patients, and explore the possible pathogenesis. Methods: A total of 134 patients with UVP presenting as EVS were included. Cochleovestibular function tests, including pure tone audiometry, caloric test, and video head impulse test (vHIT) were conducted. All patients underwent 3D-FLAIR MRI for evaluating endolymphatic hydrops (EH) and perilymphatic enhancement (PE). According to the MRI findings, patients were divided into MRI-negative (-), EH, PE, and EH + PE groups. The relationships between MRI findings and parameters of cochleovestibular function tests were analyzed. The predictive factors for abnormal MRI findings were determined. Results: Among the 134 patients with UVP included, 48.51% (65/134) had MRI-positive findings. The presence of EH, PE, and simultaneous presence of EH and PE were found in 21.64% (29/134), 17.16% (23/134), and 9.7% (13/13/4) of the patients, respectively. Compared with the MRI- group, the pure-tone average (PTA) was significantly higher in the EH (P=0.014) and EH + PE groups (P<0.05). The PE group had significantly higher canal paresis (CP) values than that in the MRI- (P<0.001), EH (P=0.003), and EH + PE groups (P<0.05), and significantly lower vHIT gain values than that in the MRI- (P=0.001), EH (P=0.001), and EH + PE groups (P<0.05). The proportion of patients with abnormal vHIT results was significantly higher in the PE group than that in the MRI- (P=0.001) and EH groups (P<0.001), which was also significantly higher in the EH + PE group than the EH group (P<0.05). The PE group had the highest prevalence of vascular risk factors (VRFs) (P<0.05). The CP value, PTA, and atherosclerotic VRFs were identified as significant and independent determinants for positive MRI findings. Conclusions: Nearly half of the patients with UVP presenting with EVS had abnormal findings on 3D-FLAIR MRI, primarily showing vestibular EH and vestibular PE. Vestibular PE occurred more frequently in the acute phase of UVP, and was often accompanied by more severe vestibular function impairment. The presence of vestibular PE may be associated with ischemic and inflammatory mechanisms. The degree of vestibular EH was positively correlated with the severity of hearing impairment. CP value >49%, PTA >30 dB, and VRFs may help to predict abnormal MRI findings in UVP presenting with EVS.