Vestibular Aqueduct and Temporal Bone Radioanatomy in patients with and without Ménière's Disease: A Retrospective Cross-Sectional Analysis with Implications for Endolymphatic Sac Surgery.

Abstract

Objective: The vestibular aqueduct (VA) shows significant anatomical variability. These anatomical variations and their relationship with neighboring structures may present technical challenges during endolymphatic sac surgery. We aimed to characterize the anatomical features of the vestibular aqueduct (VA) and its relationship with surrounding structures in patients with severe Ménière's disease compared to controls, using high-resolution computed tomography (CT).

Methods: This retrospective study included 65 patients (126 ears) who underwent temporal bone CT. The Ménière's group consisted of 26 patients (26 affected ears) meeting AAO-HNS criteria with intractable disease, the contralateral ears group included 24 ears, and the control group included 39 patients (76 ears) with unrelated conditions. Measurements included VA thickness (A), width (B/B'), distance between the posterior semicircular canal (PSCC) and posterior fossa (C), PSCC depth (D/D'), and operculum depth (E/E'). Correlations were analyzed, and k-means clustering was applied to classify anatomical variations. Reliability was assessed using intra- and inter-observer tests.

Results: VA width (B) correlated positively with PSCC-meningeal distance (C) (r=0.683, p<0.001) and negatively with PSCC depth (D') (r=-0.290, p<0.01) and operculum depth (E') (r=-0.520, p<0.001). Patients with narrower VA exhibited reduced PSCC-meningeal distance and deeper operculum positions. The Ménière's group showed significantly narrower VA and shorter PSCC-dura distances compared to controls (p<0.001). Cluster analysis identified three anatomical patterns, with 61.5% of intractable Ménière ears versus 14.5% of controls and 41.6% of the contralateral ears, in the cluster exhibiting smaller VA dimensions, shorter PSCC-dura distances, and deeper operculum positions.

Conclusion: Narrow VA correlates with reduced PSCC-meningeal distance and deeper operculum position, presenting potential challenges for endolymphatic sac surgery. These anatomical variations are more prevalent in patients with severe Ménière's disease, highlighting the need for tailored surgical approaches.