Orbital Myositis: Evaluating Five New Cases Regarding Clinical and Radiological Features

Abstract

Orbital myositis (OM) is an inflammatory disorder of the extraocular muscles. The signs and symptoms of OM are periorbital pain, eyelid swelling and redness, restricted ocular motility, and strabismus. There are at least two major forms, described by Benedikt GH Schoser, a limited oligosymptomatic ocular myositis (LOOM), which is associated with conjunctival injection only, and severe exophthalmic ocular myositis (SEOM), which presents with additional ptosis, chemosis, and proptosis. We report the clinical and radiological features of five patients with OM who were recently followed in our clinic. Three patients, one man and two women, were placed in the LOOM group, and the other two patients, both women, were in the SEOM group. In both groups, the initial complaints were pain worsening with eye movements and double vision, with only one patient in the SEOM group having pain worsening secondary to Crohn's disease. The most affected muscles were the medial and lateral recti. All the patients were treated with corticosteroids, resulting in rapid improvement. Only one patient in the SEOM group experienced a relapse. Orbital magnetic resonance imaging of all the patients revealed enlargement and contrast enhancement of the involved muscles. Although clinical and radiological features are quite consistent, delayed diagnosis in some patients demonstrates the importance of the awareness of OM.

Keywords: Orbital myositis; diplopia; extraocular muscles.

Figure 1. a, b

(a) Slight inward deviation of the right eye, associated with chemosis, proptosis and periorbital edema. (b) Orbital MRI: Enlargement and contrast enhancement of all extraocular muscles, more marked in the right medial and inferior recti (arrows)

Figure 2

Orbital MRI: Enlargement and contrast enhancement of the lateral rectus muscle

Figure 3. a, b

(a) Limited abduction of the left eye with chemosis, proptosis and periorbital edema, (b) Orbital MRI: Enlargement of the left medial rectus muscle, with contrast enhancement

Figure 4. a, b

(a) Limited abduction of the right eye. (b) Orbital MRI: Enlargement and contrast enhancement of the right medial rectus muscle

Figure 5. a, b

(a) Laterally deviated right eye together with limitation of both eye movements in all planes. (b) Orbital MRI: Enlargement and contrast enhancement of both medial recti muscles