Altered Hippocampal Subfields Functional Connectivity in Benign Paroxysmal Positional Vertigo Patients With Residual Dizziness: A Resting-State fMRI Study

Abstract

Objective: To explore alterations in functional connectivity (FC) focusing on hippocampal subfields in benign paroxysmal positional vertigo (BPPV) patients with residual dizziness (RD) after successful canalith repositioning procedure (CRP).

Methods: We conducted resting-state functional magnetic resonance imaging (fMRI) on 95 BPPV patients, comprising 50 patients with RD and 45 without. Seed-to-voxel and seed-to-seed analyses were employed to examine changes in FC between the two groups. The hippocampal subfields, including the bilateral dentate gyrus (DG), cornu ammonis (CA), entorhinal cortex (EC), subiculum, and hippocampal amygdalar transition area (HATA) were selected as seeds. Additionally, we assessed the relationship between abnormal FC and clinical symptoms.

Results: Seed-to-voxel analysis indicated that, compared to non-RD patients, those with RD exhibited decreased FC between the right DG and right parietal operculum cortex, right HATA and right precuneus, left HATA and left precuneus, left EC and cerebellar vermis 8/-crus 1, and between the left subiculum and left angular gyrus. Conversely, we observed increased FC between the left CA and left lingual gyrus, as well as between the right CA and right fusiform gyrus in RD patients. Furthermore, these variations in FC were significantly correlated with clinical features including the duration of RD and scores on the Hamilton Anxiety Scale and Dizziness Handicap Inventory.

Conclusion: BPPV patients with RD exhibited altered FC between hippocampal subfields and brain regions associated with spatial orientation and navigation, vestibular and visual processing, and emotional regulation. These findings offer novel insights into the pathophysiological mechanisms in BPPV patients with RD following successful CRP.

Keywords: benign paroxysmal positional vertigo; fMRI; functional connectivity; hippocampus; residual dizziness.

FIGURE 1

The subfields of the hippocampus. L, left; R, right; HATA, hippocampal amygdalar transition area.

FIGURE 2

Brain regions with significant differences in seed‐based functional connectivity between BPPV patients with and without RD (voxel‐level p < 0.001; cluster‐level p < 0.05 [false discovery rate (FDR) correction, two‐tailed]). BPPV, benign paroxysmal positional vertigo; RD, residual dizziness; L, left; R, right; HATA, hippocampal amygdalar transition area; PO, parietal operculum cortex; PCU, precuneus; LG, lingual gyrus; FG, fusiform gyrus; AG, angular gyrus.

FIGURE 3

The z‐value of BPPV patients with and without RD (all p < 0.0001). BPPV, benign paroxysmal positional vertigo; RD, Residual dizziness; L, Left; R, Right; DG, Dentate gyrus; HATA, Hippocampal amygdalar transition area; CA, Cornu ammonis; EC, Entorhinal cortex; Subc, Subiculum; PO, parietal operculum cortex; PCU, Precuneus; LG, Lingual gyrus; FG, Fusiform gyrus; AG, Angular gyrus.

FIGURE 4

(A) The z‐value between right dentate gyrus (DG) and right parietal operculum (PO) cortex was negatively correlated with the duration of residual dizziness (p = 0.005, r = −0.526); (B) The z‐value between right hippocampal amygdalar transition area (HATA) and right precuneus (PCU) was negatively correlated with the scores of Hamilton Anxiety Scale (p = 0.003, r = −0.471); (C) The z‐value between left cornu ammonis (CA) and left lingual gyrus (LG) was positively correlated with the scores of Dizziness Handicap Inventory (DHI) after successful canalith repositioning procedure (CRP) (p = 0.001, r = 0.513).