Abstract
ObjectiveRadiological anatomical variations, measured by magnetic resonance imaging (MRI), were evaluated in patients with ipsilateral delayed endolymphatic hydrops (DEH) and unilateral Ménière’s disease (MD). The role of anatomical variations in different subtypes of hydropic ear disease was investigated.MethodsTwenty-eight patients with ipsilateral DEH, 76 patients with unilateral MD, and 59 control subjects were enrolled. The radiological indices included the distance between the vertical part of the posterior semicircular canal and the posterior fossa (MRI-PP distance) and the visibility of vestibular aqueduct (MRI-VA). These variations among patients with DEH, MD, and control subjects were compared. The correlation between radiological anatomical variations and clinical features or audio-vestibular findings was also examined.Results(1) MRI-PP distance in the affected side of unilateral MD was shorter than that in ipsilateral DEH (Z = − 2.481, p = 0.013) and control subjects (Z = − 2.983, p = 0.003), while the difference of MRI-PP distance between the affected side of ipsilateral DEH and control subjects was not statistically significant (Z = − 0.859, p = 0.391). (2) There was no significant interaural difference of MRI-PP distance in patients with unilateral MD (Z = − 0.041, p = 0.968) and ipsilateral DEH (t = − 0.107, p = 0.915) respectively. (3) No significant interaural difference of MRI-VA visibility was observed in patients with unilateral MD (χ2 = 0.742, p = 0.389) and ipsilateral DEH (χ2 = 0.327, p = 0.567) respectively. (4) No correlation was found between these anatomical variables and clinical features or audio-vestibular findings in patients with unilateral MD and ipsilateral DEH respectively (p > 0.05).ConclusionsAnatomical variations of inner ear may be a predisposing factor in the pathogenesis of unilateral MD rather than ipsilateral DEH.Key Points• Patients with ipsilateral delayed endolymphatic hydrops showed normal distance between the vertical part of the posterior semicircular canal and the posterior fossa.• Compared to patients with ipsilateral delayed endolymphatic hydrops and control subjects, patients with unilateral Ménière’s disease exhibited shorter distance between the vertical part of the posterior semicircular canal and the posterior fossa.• Anatomical variations of inner ear may be a predisposing factor in the pathogenesis of unilateral Ménière’s disease rather than ipsilateral delayed endolymphatic hydrops.
Highlights
Ménière’s disease (MD) is a relatively common and debilitating otological condition characterized by repetitive vertiginous episodes, fluctuant sensorineural hearing loss (SNHL), tinnitus, and aural fullness
action potential (AP) Action potential canal paresis (CP) Canal paresis computed tomography (CT) Computed tomography delayed endolymphatic hydrops (DEH) Delayed endolymphatic hydrops EcochG Electrocochleogram endolymphatic duct (ED) Endolymphatic duct ELH Endolymphatic hydrops endolymphatic sac (ES) Endolymphatic sac FOV Field of view intraclass correlation efficient (ICC) Interclass correlation efficient IQR Interquartile range MD Ménière’s disease magnetic resonance imaging (MRI) Magnetic resonance imaging MRI-PP distance Distance between the vertical part of the posterior semicircular canal and the posterior fossa visualized by MRI picture archiving and communication system (PACS) Picture archiving and communication system standard deviations (SDs) Standard deviations SNHL Sensorineural hearing loss summating potential (SP) Summating potential SPVmax Maximum slow phase velocity vestibular aqueduct (VA) Vestibular aqueduct
MD Ménière’s disease, DEH delayed endolymphatic hydrops; MRI-PP Distance distance between the vertical part of the posterior semicircular canal and the posterior fossa visualized by MRI, MRI-VA visibility visualization of the vestibular aqueduct by MRI
Summary
Ménière’s disease (MD) is a relatively common and debilitating otological condition characterized by repetitive vertiginous episodes, fluctuant sensorineural hearing loss (SNHL), tinnitus, and aural fullness. The pathological hallmark of MD is endolymphatic hydrops (ELH), its role in the pathophysiology of the disease remains unclear. Many factors have been proposed as leading to the development of ELH, which involve excessive endolymph production and decreased endolymph absorption by the endolymphatic sac (ES), ionic imbalance, genetic predisposition, anatomical abnormalities, viral infection, autoimmune reactions, vascular irregularities, allergic responses, and others [1]. The anatomical variations of the inner ear have been studied histopathologically and radiologically [2]. Radiological studies have found various anatomical variations of the inner ear in MD patients, as visualized on magnetic resonance imaging (MRI) or computed tomography (CT), including reduced distance between the vertical part of the posterior semicircular canal and the posterior fossa, less visibility of endolymphatic duct (ED) or VA [5–7], poor periaqueductal pneumatization [8], higher prevalence of jugular bulb abnormalities [9], retro-vestibular bony hypoplasia [10], and so forth
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