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

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.