The vestibular aqueduct ossification on temporal bone CT: an old sign revisited to rule out the presence of endolymphatic hydrops in Meniere's disease patients

Objectives Meniere's disease (MD) is associated with endolymphatic hydrops (EH), which is an accumulation of excessive endolymphatic fluid in the inner ear. However, using temporal bone CT, lower visualization rates of the vestibular aqueduct (VA) in these patients have also been reported. Methods In this retrospective single-center imaging study, we have included 25 healthy subjects and 47 patients having a definite, probable, or possible clinical diagnosis of MD that underwent temporal bone CT and inner ear MRI performed 4 h after contrast media administration. Two radiologists independently ranked the morphology of the VA in healthy subjects and in MD patients, using a three-level score (completely visible, discontinuous, and not visible). Each subject was then graded, based on both the VA's appearance and on EH presence. Results In healthy subjects, the VA was normal (grade 0) in 22/25 (88%) ears and discontinuous (grade I) in 3 healthy ears (12%). In the symptomatic ears of MD patients, we found 17/56 ears (30.3%) with VA grade 0, 15/56 ears (26.8%) with grade I, and 24/56 ears (42.8%) with grade II (p< 0.001). In MD patients, EH was observed in 46/94 ears (48.9%). A VA of grade 0 would eliminate the presence of EH with a negative predictive value of 88.6%, while a VA grade II would predict the presence of saccular hydrops with a positive predictive value of 93.1%. Conclusion The evaluation by temporal bone CT of the VA can predict the presence of EH on MRI with a high positive predictive value.