Abnormal regional spontaneous neural activity and functional connectivity in thyroid-associated ophthalmopathy patients with different activity: a resting-state fMRI study

Disrupted topology of the functional white matter connectome in thyroid-associated ophthalmopathy

BACKGROUND

This study aims to investigate the changes in the topological organization of WM functional connectivity in individuals with TAO, providing a novel and insightful perspective on the functional disruptions that characterize this condition.

METHODS

This study utilized resting-state functional Magnetic Resonance Imaging (rs-fMRI) to capture blood-oxygen-level-dependent (BOLD) signals and T1-weighted images from patients with TAO and healthy control subjects. Group-level masks for white matter were created to extract WM-related BOLD signals, facilitating the construction of a functional white matter network. Graph theory analysis was subsequently conducted to evaluate global metrics, nodal metrics, and modularity, alongside network-based analysis. Finally, support vector machines (SVM) were employed for classification.

RESULTS

A functional white matter network comprising 128 nodes and their respective connections was identified. The graph theory analysis revealed significant differences primarily in the sigma characteristic of the global small-world metrics, with a notable decrease in betweenness centrality observed in the splenium of the corpus callosum. Modularity analysis indicated significant intra-module variations in modules 03 and 05, while strong inter-module connections were observed between modules 01 and 03, as well as between modules 02 and 04. Furthermore, network-based statistics (NBS) highlighted 13 networks that exhibited significant alterations in the TAO group compared to healthy controls, underscoring the potential impact of TAO on the organization of white matter networks.

CONCLUSION

In our study, we found that patients with TAO exhibited abnormalities in the white matter functional network regarding small-world metrics and modularity, which are related to visual and cognitive functions.

Neuroimaging in thyroid eye disease: A systematic review

Thyroid eye disease (TED) is an organ-specific autoimmune disease secondary largely to hyperthyroid Graves' disease, which profoundly affects patients' visual function, appearance, and physical and mental well-being. Emerging neuroimaging studies have reported alterations in the brains of patients with TED, suggesting that the impact of this autoimmune disease may extend beyond the orbit. This systematic review aims to consolidate the neuroimaging evidence that describes the brain alterations of TED. We analyzed information from thirty-one related studies involving 1349 TED patients and 710 healthy controls, employing multimodal neuroimaging techniques such as structural magnetic resonance imaging (MRI), functional MRI, diffusion MRI, and metabolic MRI. These studies define the brain alterations in regions associated with vision, cognition, and emotion regulation, such as gray matter volume changes, altered functional connectivity and activity, and microstructural modifications, revealing the neurological impact of TED beyond the orbit. Notably, there was convergence across these studies indicating predominant abnormalities within the occipital and parietal lobes. This review underscores the critical role of advanced neuroimaging techniques in unraveling the complex neuropathological mechanism of TED, laying a foundation for future research and potential therapeutic targets.

The insular cortex is not insular in thyroid eye disease: neuroimaging revelations of central-peripheral system interaction

BACKGROUND

Thyroid eye disease (TED) is highly correlated with dysregulated immunoendocrine status. The insular cortex was found to regulate peripheral inflammation and immunomodulation in mice. This study aimed to explore whether the insular cortex in patients with TED played a modulatory role including the aberrant brain functional alteration and its association with immunoendocrine status.

METHODS

This study included 34 active patients (AP), 30 inactive patients (IP) with TED, and 45 healthy controls (HC) matched for age, sex, and educational level. Comprehensive clinical details (especially immunoendocrine markers) and resting-state functional magnetic resonance imaging data were collected from each participant. The amplitude of low-frequency fluctuation (ALFF) was used to probe the aberrant alterations of local neural activity. The seed-based functional connectivity (FC) analysis was used to explore the relationship between the insular cortex and each voxel throughout the whole brain. The correlation analysis was conducted to assess the association between insular neurobiomarkers and immunoendocrine parameters.

RESULTS

When compared with the IP and HC groups, the AP group displayed significantly higher ALFF values in the right insular cortex (INS.R) and lower FC values between the INS.R and the bilateral cerebellum. None of the neurobiomarkers differed between the IP and HC groups. Besides, correlations between insular neurobiomarkers and immunoendocrine markers (free thyroxine, the proportion of T cells, and natural killer cells) were identified in both AP and IP groups.

CONCLUSIONS

This study was novel in reporting that the dysregulation of the insular cortex activity in TED was associated with abnormal peripheral immunoendocrine status. The insular cortex might play a key role in central-peripheral system interaction in TED. Further research is crucial to enhance our understanding of the central-peripheral system interaction mechanisms involved in autoimmune diseases.