Lacrimal glands herniation in patients with Graves’ Ophthalmopathy: an effective MRI-derived marker of disease activity

Aims and objectives Graves ophthalmopathy (GO) is the most common extrathyroidal manifestation of Graves disease. It is important to identify the acute inflammation phase at an early stage to improve GO clinical outcomes. The lacrimal gland (LG) involvement in patients with GO has been considered as a potential cause of the associated GO symptoms and different studies found that the LG measurements were significantly higher in patients with GO than healthy controls. However, no data are available about the difference in LC volume between patients with different GO activity. We evaluated the LG involvement measuring glands herniation by the use of magnetic resonance imaging (MRI), in patients with different GO activity. Methods and materials Thirty-two consecutive Caucasic patients (10 M, 22 F, mean age 49.5, IR 30-68 yrs), affected by GO were enrolled and grouped in group A (n 16 with inactive GO, CAS<3) and B (n 16 with active GO, CAS≥3) according to their GO activity. All patients underwent to a clinical, biochemical and morphological thyroid assessment, a complete ocular evaluation and an orbital MRI examination. Lacrimal glands herniation has been evaluated on axial MRI sequences by drawing a line between the right and left ventral zygomatic border (interzygomatic line). This line is commonly drawn at the level of the lens to evaluate the amount of proptosis (from there, a perpendicular line is taken to the apex of the globe, depicting the measurement of proptosis considering an Hertel-index of ≥22 mm pathological). We drawn the interzygomatic line also at the level of the maximum depicted lacrimal glands herniation and, taking a perpendicular line, we measured the amount of lacrimal gland parenchyma protruding anteriorly (i.e.: lacrimal gland herniation). Results No significant difference was found for the hormonal parameters and thyroid ultrasound-derived parameters between the two groups. TRAb levels resulted slightly higher, although not significantly, in group B [2.76 (0-40) vs. 1.74 (0-13.8) UI/L; p=0.073)]. The LC herniation measurement MRI-evaluated was significantly higher in the group B for both right [10.1 (7.3-17) vs. 7 (0-13.4) mm; p=0.004)] and left [8.5 (6.6-13) vs. 5.8 (0-12) mm; p=0.026)] eye than group A. A linear correlation was found between TRAb levels and LC herniation (Rho 0.462, p=0.009) in all patients Conclusion The measurement of the lacrimal gland herniation seems to be a good marker of the activity of GO as evidenced by the significant difference between the two groups of patients. The correlation between TRAb levels and the degree of lacrimal gland herniation may suggest a more relevant role of the lacrimal gland involvement in the pathogenesis of GO. Future