Extraocular muscle volume on time-of-flight magnetic resonance angiography in patients with myasthenia gravis

Pei Chen MD, PhD, Qin Zhou MD, Xiaoxiao Zhao BS, Yingqian Chen MD, PhD, Zhongqiang Lin MD, Mengzhu Wang MD, Zhiyun Yang MD, PhD, Weibin Liu MD, PhD

Introduction/Aims Despite being a prominent feature of myasthenia gravis (MG), extraocular muscle (EOM) has received little attention in clinical research. The aim of this study was to examine EOM volume in patients with MG and controls using time-of-flight magnetic resonance angiography (TOF-MRA).

Methods EOM volumes (overall and individual rectus muscles) were calculated using TOF-MRA images and compared between MG patients (including subgroups) and controls. The correlation between EOM volume and disease duration was examined. Predictive equations for the selected parameters were developed using multiple linear regression analysis.

Results EOM volume was lower in MG patients than controls, especially in MG patients with ophthalmoparesis (MG-O). MG-O exhibited a moderate negative correlation between EOM volume and disease duration. Multiple linear regression showed that disease duration and EOM status (ophthalmoparesis or not) account for 48.4% of EOM volume.

Discussion Patients with MG show atrophy of the EOMs, especially those with ophthalmoparesis and long disease duration.

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