Endolymphatic hydrops and intracranial hypertension: a quantitative MRI analysis.

Objective: This study investigated the prevalence and association of magnetic resonance imaging (MRI) imaging markers indicative of idiopathic intracranial hypertension (IIH) in patients diagnosed with endolymphatic hydrops (EH). The objective was to elucidate potential pathophysiological links between inner ear fluid dysregulation and alterations in intracranial pressure. Methods: A total of 108 adult patients with dedicated MRI and delayed post-contrast (hydrops) sequences obtained for assessment of auditory/vestibular symptoms between 01/2020 and 06/2025 were retrospectively reviewed. EH grading, nerve volumes of the cochlear nerve, common vestibular trunk and facial nerve, IIH imaging features (e.g., Meckel's cave dilatation, optic nerve findings, venous sinus stenosis), and clinical symptoms were recorded. The prevalence and co-occurrence of EH and IIH features were statistically analyzed. Results: Vestibular EH (grade 2) was noted in 71.3% (right) and 60.2% (left) of patients and cochlear EH (grade 2) in 42.6% (left) and 34.3% (right) of patients. IIH-related imaging markers were common: bilateral Meckel's cave dilatation (60.2%), partially empty sella turcica (50.9%), bilateral optic nerve sheath dilation (57.4%), optic nerve head enhancement on delayed FLAIR sequences (67.6%), and intrinsic bilateral transverse sinus stenosis (26.9%). Statistically significant associations were identified between vestibular EH severity and optic nerve sheath dilation (p = 0.0368), optic nerve tortuosity (p = 0.0309), slit-like lateral ventricles (p = 0.0023), and increased subcutaneous fat thickness in the scalp and neck (p = 0.003). Conversely, intrinsic bilateral transverse sinus stenosis was negatively correlated with EH severity (ρ = -0.228, p = 0.017). Overlap analyses demonstrated that many patients with moderate to severe EH exhibited multiple IIH imaging features concomitantly. Conclusion: MRI findings demonstrate a frequent coexistence of EH and radiological biomarkers of IIH. This observation supports a potential pathophysiological association between inner ear fluid dysregulation and elevated intracranial pressure, underscoring the need for prospective studies integrating clinical outcomes with advanced MRI-based assessments of fluid dynamics.