Resting-State Brain Activity, Functional Connectivity, and Orbital Imaging Changes in Restrictive Myopathy Associated...

Restrictive myopathy is an important subtype of thyroid eye disease (TED) characterized by ocular motility restriction. Emerging evidence has indicated brain remodeling in TED restrictive myopathy, yet the underlying mechanism remains elusive. Therefore, this study aims to investigate brain activity and extraocular muscles (EOMs) abnormalities in TED restrictive myopathy, providing a deeper insight into the relationship between ocular motility restriction and brain functional changes.

This prospective observational study recruited 45 TED patients recruited (28 with restrictive myopathy and 17 without). Brain function parameters and EOMs metrics were obtained. The two-sample t test was performed to compare intergroup differences, and correlation analysis was applied to uncover the association between brain functional activity and EOMs involvement.

TED restrictive myopathy exhibited increased intraocular pressure (IOP), long diameters (LD) and short diameters (SD) of inferior rectus, and decreased visual functioning score in Graves' orbitopathy-specific quality of life questionnaire (GO-QoL). Increased amplitude of low-frequency fluctuations (ALFF) in the left middle temporal gyrus (MTG.L) were found in TED restrictive myopathy. The functional connectivity (FC) analysis further discovered higher FC between MTG.L and the right cerebellum_8 and bilateral middle frontal gyrus (MFG). The brain imaging parameters were significantly correlated with vertical deviation, exophthalmos and EOMs metrics in TED restrictive myopathy.

This study explored the brain alterations in TED restrictive myopathy, underscoring oculomotor restriction-associated brain functional changes. The study also serves as a preliminary exploration of the alterations in visual pathway in restrictive strabismus, represented by TED with restrictive myopathy.