Morphometric evaluation of facial and vestibulocochlear nerves using magnetic resonance imaging in patients with Menière's disease.

Background and purpose: Menière's disease (MD) is a condition of unknown etiology, involving genetic predisposition, autoimmune processes, viral infections, cellular apoptosis, and oxidative stress. This study aimed to investigate potential differences in the VII^th and VIII^th cranial nerves in MD patients using Hydrops-MRI (FLAIR) for morphometric evaluations.

Materials and methods: Using a 3T MRI scanner, constructive-interference-in-steady-state (CISS) and 3D-FLAIR-inversionrecovery (FLAIR) sequences were acquired. We evaluated the morphometrics of the VII^th and VIII^th cranial nerves from the cerebellopontine angle to the internal auditory canal fundus, comparing the non-affected and affected sides. Furthermore, we examined the findings in relation to symptom duration and evaluated feasibility of FLAIR-imaging in morphometry of cranial nerves.

Results: A total of 53 MD patients with unilateral symptoms were included. After statistical analysis, no significant differences were found regarding morphometric changes in the affected side compared to the non-affected side of the VII^th and VIII^th cranial nerves. There was also no significant difference between morphometric evaluations of patients with different symptom durations. The morphometric evaluation using Hydrops-MRI-Sequences (FLAIR) showed no significant difference compared to established morphometric highly T2-weighted imaging (CISS).

Conclusions: Our data found no differences in nerve morphometry between clinically non-affected and affected sides in unilateral MD patients, nor any correlation with symptom duration. This contrasts with previous findings of correlations between clinical features and endolymphatic hydrops. A disease process starting before clinical symptom onset could be a possible explanation. Morphometric evaluation of brain nerves using Hydrops-MRI-Sequences is practical and provides similar results to T2-weighted imaging, improving patient comfort and reducing MRI scan time.

Abbreviations: CN = cochlear nerve; CPA = cerebellopontine angle; CSA = cross-sectional area; FN = facial nerve; IAC = internal auditory canal; IVN = inferior vestibular nerve; LD = long diameter; MD = Menière's disease; SD = short diameter; SVN = superior vestibular nerve.