Concurrent brain structural and functional alterations in patients with chronic unilateral vestibulopathy

Chronic unilateral vestibulopathy (CUVP) is a common chronic vestibular syndrome which may be caused by incomplete vestibular dynamic compensation. Neuroimaging technology provides important clues to explore the mechanism of complicated by vestibular dynamic compensation in patients with CUVP. However, previous studies mostly used positron emission tomography (PET) and functional magnetic resonance imaging (fMRI) to investigate the changes of brain function in these patients during the task state, few studies have investigated the alterations during the resting state, Therefore, the study aimed to investigate the possible brain structural and functional alterations in patients with CUVP and explore the dynamic compensation state in patients with CUVP.

We recruited 18 patients with right CUVP and 18 age-, gender-, and education level-matched healthy controls (HCs). Vestibular evaluations, such as videonystagmography and caloric tests, were performed. All participants underwent Dizziness Handicap Inventory (DHI) assessment. All participants underwent multimodal magnetic resonance imaging of the brain, including fMRI and three-dimensional T1-weighted MRI. We analyzed the amplitude of low frequency fluctuations (ALFF), regional homogeneity (ReHo), seed based functional connectivity, and voxel-based morphometry (VBM).

Compared with HCs, CUVP patients showed significantly increased ALFF values in the right supplementary motor area, significantly decreased ALFF values in the right middle occipital gyrus, significantly decreased ReHo values in the bilateral superior parietal lobule, and significantly enhanced ReHo values in the bilateral cerebellar hemisphere [both P<0.05, family-wise error (FWE) corrected]. Compared with HCs, patients with CUVP showed increased gray matter volumes in the left medial superior frontal gyrus and left middle cingulate gyrus [P<0.001, false discovery rate (FDR) corrected]. Compared with HCs, in patients with CUVP, functional connectivity was enhanced between the left medial superior frontal gyrus and the left orbital inferior frontal gyrus and left angular gyrus and was significantly decreased between the left medial superior frontal gyrus and the right dorsolateral superior frontal gyrus (both P<0.01, FWE corrected). Pearson correlation analysis showed that there was a positive correlation between DHI score and VBM value of the left medial superior frontal gyrus in patients with CUVP (r=-0.430, P=0.003).

This study identified abnormalities of neuronal activity intensity and overall activity synchronization in multiple brain regions in patients with CUVP, suggesting that patients with CUVP have extensive brain functional abnormalities, which in turn affects their spatial perception and motor perception. Increased gray matter volume and functional connectivity of the default mode network may be used as potential imaging biomarkers of chronic symptoms in patients with CUVP.