Meniere’s disease (MD) is a chronic disorder of inner ear, characterized by audial and vestibular symptoms. It presents a great variability among patients in terms of clinical features, etiology, p...

(1) Background: Vestibular migraine (VM) and Meniere’s disease (MD) share multiple features in terms of clinical presentations and auditory-vestibular dysfunctions, e.g., vertigo, hearing loss, and headache. Therefore, differentiation between VM and MD is of great significance. (2) Methods: We retrospectively analyzed the medical records of 110 patients with VM and 110 patients with MD. We at first established a regression equation by using logistic regression analysis. Furthermore, sensitivity, specificity, accuracy, positive predicted value (PV), and negative PV of screened parameters were assessed and intuitively displayed by receiver operating characteristic curve (ROC curve). Then, two visualization tools, i.e., nomograph and applet, were established for convenience of clinicians. Furthermore, other patients with VM or MD were recruited to validate the power of the equation by ROC curve and the Gruppo Italiano per la Valutazione degli Interventi in Terapia Intensiva (GiViTI) calibration belt. (3) Results: The clinical manifestations and auditory-vestibular functions could help differentiate VM from MD, including attack frequency (X5), phonophobia (X13), electrocochleogram (ECochG) (X18), head-shaking test (HST) (X23), ocular vestibular evoked myogenic potential (o-VEMP) (X27), and horizontal gain of vestibular autorotation test (VAT) (X30). On the basis of statistically significant parameters screened by Chi-square test and multivariable double logistic regression analysis, we established a regression equation: P = 1/[1 + e^{−(−2.269× X5 − 2.395× X13 + 2.141× X18 + 3.949 × X23 + 2.798× X27 − 4.275× X30(1) − 5.811× X30(2) + 0.873)}] (P, predictive value; e, natural logarithm). Nomographs and applets were used to visualize our result. After validation, the prediction model showed good discriminative power and calibrating power. (4) Conclusions: Our study suggested that a diagnostic algorithm based on available clinical features and an auditory-vestibular function regression equation is clinically effective and feasible as a differentiating tool and could improve the differential diagnosis between VM and MD.

Aims: To investigate changes in functional connectivity (FC) focusing on parietal operculum cortex 2 (OP2) in benign paroxysmal positional vertigo (BPPV) patients with residual dizziness (RD) after successful canalith repositioning procedure (CRP). Methods: High‐resolution three‐dimensional T1 and resting‐state functional magnetic resonance imaging (fMRI) were performed on 55 healthy controls (HCs), 55 BPPV patients with RD, and 55 patients without RD after successful CRP. Seed‐based (bilateral OP2) FC was calculated to investigate the changes in FC among the three groups. Additionally, we further explored the associations between abnormal FC and clinical symptoms. Results: One‐way analysis of covariance showed significant FC differences among the three groups. Post‐hoc analysis showed that patients with RD exhibited decreased FC between left OP2 and regions of left angular gyrus (AG), thalamus, precuneus, middle frontal gyrus (MFG), and right cerebellum posterior lobe (CPL) in comparison with HCs. In addition, compared with patients without RD, patients with RD showed decreased FC between left OP2 and regions of left MFG, AG, middle temporal gyrus, and right CPL. Moreover, in patients with RD, the FC between left thalamus and OP2 was negatively correlated with duration of RD, and the FC between left AG and OP2 was negatively correlated with duration of BPPV. Conclusion: BPPV patients with RD showed reduced FC between brain regions involved in vestibular processing and spatial cognition; These results suggested that BPPV patients with RD might have diminished central processing of vestibular information and impaired spatial cognition.

(1) Background: Vestibular migraine (VM) and Menière’s disease (MD) share multiple features in terms of clinical presentations and auditory-vestibular functions, and, therefore, more accurate diagnostic tools to distinguish between the two disorders are needed. (2) Methods: The study was of retrospective design and examined the data of 69 MD patients, 79 VM patients and 72 MD with migraine patients. Five vestibular autorotation test (VAT) parameters, i.e., horizontal gain/phase, vertical gain/phase and asymmetry were subjected to logistic regression. The receiver operating characteristic (ROC) curves were generated to determine the accuracy of the different parameters in the differential diagnosis of MD and VM. (3) Results: Our results showed that the horizontal gain of VAT significantly outperformed other parameters in distinguishing MD and VM. In addition, the sensitivity, specificity and accuracy of the horizontal gain were 95.7%, 50.6% and 71.6%, respectively, for the differentiation between VM and MD. In most MD patients, the horizontal gain decreased in the range of 3–4 Hz, while in most VM patients, horizontal gain increased in the range between 2–3 Hz. More MD with migraine patients had an increased horizontal gain when the frequency was less than 5.0 Hz and had a decreased horizontal gain when the frequency was greater than 5.0 Hz. (4) Conclusion: Our study suggested the VAT, especially the horizontal gain, as an indicator, may serve as a sensitive and objective indicator that helps distinguish between MD and VM. Moreover, VAT, due to its non-invasive and all-frequency nature, might be an important part of a test battery.

Aims: To investigate the role of mGluR1α in cerebellar unipolar brush cells (UBC) in mediating vestibular compensation (VC), using mGluR1α agonist and antagonist to modulate ON UBC neurons, and explore the mGluR1/IP3/extracellular signal‐regulated kinase (ERK) signaling pathway. Methods: First, AAV virus that knockdown ON UBC (mGluR1α) were injected into cerebellar UBC by stereotactic, and verified by immunofluorescence and western blot. The effect on VC was evaluated after unilateral labyrinthectomy (UL). Second, saline, (RS)‐3,5‐dihydroxyphenylglycine (DHPG), and LY367385 were injected into tubes implanted in rats at different time points after UL separately. The effect on ON UBC neuron activity was evaluated by immunofluorescence. Then, Phosphoinositide (PI) and p‐ERK1/2 levels of mGluR1α were analyzed by ELISA after UL. The protein levels of p‐ERK and total ERK were verified by western blot. In addition, the effect of mGluR1α activation or inhibition on VC‐related behavior was observed. Results: mGluR1α knockdown induced VC phenotypes. DHPG increased ON UBC activity, while LY367385 reduced ON UBC activity. DHPG group showed an increase in PI and p‐ERK1/2 levels, while LY367385 group showed a decrease in PI and p‐ERK1/2 levels in cerebellar UBC of rats. The western blot results of p‐ERK and total ERK confirm and support the observations. DHPG alleviated VC‐related behavior phenotypes, while LY367385 exacerbated vestibular decompensation‐like behavior induced by UL. Conclusion: mGluR1α activity in cerebellar ON UBC is crucial for mediating VC through the mGluR1/IP3/ERK signaling pathway, which affects ON UBC neuron activity and contributes to the pathogenesis of VC.

Vestibular compensation is a natural behavioral recovery process following unilateral vestibular injury. Understanding the mechanism can considerably enhance vestibular disorder therapy and advance the adult central nervous system functional plasticity study after injury. The cerebellum, particularly the flocculonodular lobe, tightly modulates the vestibular nucleus, the center for vestibular compensation; however, it is still unclear if the flocculus on both sides is involved in vestibular compensation. Here we report that the unipolar brush cells (UBCs) in the flocculus are modulated by unilateral labyrinthectomy (UL). UBCs are excitatory interneurons targeting granule cells to provide feedforward innervation to the Purkinje cells, the primary output neurons in the cerebellum. According to the upregulated or downregulated response to the mossy fiber glutamatergic input, UBC can be classified into ON and OFF forms of UBCs. Furthermore, we discovered that the expression of marker genes of ON and OFF UBCs, mGluR1α and calretinin, was increased and decreased, respectively, only in ipsilateral flocculus 4–8 h after UL. According to further immunostaining studies, the number of ON and OFF UBCs was not altered during UL, demonstrating that the shift in marker gene expression level in the flocculus was not caused by the transformation of cell types between UBCs and non-UBCs. These findings imply the importance of ipsilateral flocculus UBCs in the acute response of UL, and ON and OFF UBCs may be involved in vestibular compensation in opposite directions.