Endocrine Abstracts

Graves’ orbitopathy (GO) is an auto-immune disorder that targets intra-orbital tissues. It is well proven to involve inflammatory hypertrophy of the rectus EOMs. Superior oblique (SO) muscle has been sporadically reported to be involved in GO. However, there are extremely few reports in the literature that refer to the involvement of the inferior oblique (IO) muscle and here we present such a case.

A 33-year-old man with unilateral exophthalmos was referred to our clinic. Mild swelling of both eyelids was present, along with mild eyelid redness, chemosis and redness of the conjunctiva and swelling of the caruncle and plica, in both eyes. Sign of attentive gaze and upper eyelid retraction were observed, notably at the left, so that the left eye manifested a 3 mm distance of upper eyelid from the upper limbus. Palpebral aperture was assessed (right eye was measured 11 mm and left eye 14 mm). The patient suffered of double vision at all gaze positions, being more severe at upgaze, with moderate motility, mainly of the left eye, on up-gaze. Hertel evaluation revealed exophthalmos of the left eye. Clinically and biochemically he was hyperthyroid, with positive TRAbs. A STIR magnetic resonance imaging of the orbits showed minimal active inflammation and enlargement of all four rectus extra-ocular muscles (EOMs), bilaterally, with a very impressive enlargement of the inferior oblique muscles in both eyes. The patient was diagnosed with GO and received i.v. steroid treatment (i.v.-STx) of 12 weekly doses (cumulative dose 4. 5 g methylprednisolone). A significant clinical and imaging improvement was observed at the end of the i.v.-STx. Repeated MRI showed significant reduction of the dimensions of the EOMs, with the inferior oblique returning back to almost normal size.

Thus inferior oblique enlargement, although rare, can also be involved in patients with GO.