Reduced Gray Matter Volume Seen in Patients With Vestibular Migraine

Functional connectivity (FC) between regions with a decline in gray matter (GM) volume is altered in patients with vestibular migraine (VM), according to study results published in Frontiers in Neuroscience. Findings suggest that abnormalities in the vestibular cortical network may be useful for understanding the underlying mechanisms of VM, authors wrote.

Although the exact pathophysiology of VM is not fully understood, it is the most common neurological cause of vertigo and affects between 1% and 2.7% of the adult population.

“Previous studies suggest that recurring migraine and vertigo attacks over time may lead to selective damage to several brain regions involved in pain and visual and vestibular processing,” researchers explained. “Furthermore, VM may have cumulative effects on brain structure, because some alterations may be associated with a longer disease duration and increased migraine frequency.”

Using multimodal imaging approaches by combining voxel-based morphometry (VBM) and resting state FC analyses, investigators sought to identify changes in GM volume and abnormal FC in patients with VM during the interictal period.

A total of 30 patients with VM (24 without aura, 6 with aura) were recruited from an outpatient center in China between January 2016 and October 2020. All participants did not take medications for at least 3 days prior to their functional MRI (fMRI) scan.

All patients were also required to be attack-free during the experiment and underwent MRIs in the following 3 to 7 days after a VM attack. Thirty healthy controls (HCs) were included in the final analyses.

Researchers found:

• Compared with HCs, patients with VM showed significantly decreased GM volume in the left posterior insula, parietal operculum, superior temporal gyrus (parieto-insular vestibular cortex [PIVC]), right middle frontal gyrus, right posterior insular/parietal operculum region, and precuneus.
• No significant increase in GM volume was detected.
• Only GM volume in the left PIVC showed a significant negative correlation with Dizziness Handicap Inventory (DHI) score in patients with VM (r = −0.508; P = .005).
• Based on whole brain voxel-wise correlation analysis, there was no correlation between GM volume and clinical variables.
• Compared with HCs, patients with VM showed increased FC between the primary somatosensory cortex/inferior parietal lobule and the left PIVC.
• No regions showed a significant decrease in FC with the left PIVC in patients with VM.
• The correlation analysis failed to identify any significant correlation between changes in FC and clinical characteristics in patients with VM.

“Our present data demonstrate changes in FC in resting-state networks of brain regions with structural alterations,” the authors noted.

The main finding of a significant loss of GM volume in the PIVC among those with VM is in line with previous studies; this region “is recognized as the core region of the vestibular cortex in humans,” they continued.

As impaired GM volume in the PIVC was negatively correlated with the DHI score, this relationship underscores that recurring long-term headache and vertigo attacks have a cumulative effect on GM volume. Abnormal GM volume may thus contribute to dysfunction in information processing, supporting the notion that impaired GM volume is linked with the pathophysiology of VM.

In addition, “it is possible to speculate that the GM volume reductions of the PIVC led to a systems-level alteration in FC,” authors wrote, although more studies are needed to answer this question.

The relatively small sample size and lack of a comparative study among migraine subtypes (aura vs no aura) mark limitations to the current analysis. The cross-sectional nature of the study also precludes any causal conclusions from being drawn.

Reference

Zhe X, Zhang X, Chen L, et al. Altered gray matter and functional connectivity in patients with vestibular migraine. Front Neurosci. Published online July 8, 2021. doi:10.3389/fnins.2021.683802