Purpose

To report a rare initial presentation of idiopathic orbital myositis combining ptosis and mixed ophthalmoplegia

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Methods

A 52-year-old female patient, with no prior medical history, was seen in the emergency department for progressive bilateral drooping of the upper eyelid associated with binocular diplopia.

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Results

The ophthalmological examination revealed visual acuity of 6/10 in the right eye (RE) , 4/10 in the left eye (LE), and bilateral ptosis. Examination of the anterior segment and fundus was unremarkable. Oculomotor examination showed: a deficit in elevation and partial limitation of adduction in both the RE and LE, and a marked limitation of abduction. Furthermore, there was no pain on eye movement, no exophthalmos, no conjunctival redness, and no fluctuation of symptoms at the end of the day or with exertion.
Immunological testing and viral serologies were negative. A biopsy of the levator palpebrae superioris muscle in the OD revealed a non specific inflammatory infiltrate. Orbital and cerebral magnetic resonance imaging showed homogeneous thickening of the medial rectus muscle on the right and the lateral rectus muscle on the left. A diagnosis of idiopathic orbital myositis was made. Corticosteroid therapy with methylprednisolone boluses was initiated, followed by oral administration. The patient’s condition improved rapidly, with diplopia and progressive recovery of oculomotor function.

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Conclusion

Idiopathic orbital myositis is rare and belongs to the group of nonspecific inflammatory orbitopathies. It can present in atypical, sometimes misleading forms, such as mimicking oculomotor palsy. The combination of ptosis, mydriasis, and limited motility necessitates first ruling out serious etiologies such as a posterior communicating artery aneurysm or cavernous sinus involvement. The rapid response to corticosteroids, in the absence of other etiological evidence, increases the diagnostic suspicion of idiopathic myositis. Multidisciplinary collaboration is essential for optimal therapeutic management of these atypical presentations.

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Additional Authors

First name	Last name	Base Hospital / Institution
Amine	Chachia	Tahar Sfar University Hospital Mahdia
Sameh	Mbarek	Tahar Sfar University Hospital Mahdia
Nada	Sakli	Tahar Sfar University Hospital Mahdia
Ahmed	Jakhlouti	Tahar Sfar University Hospital Mahdia
Anis	Mahmoud	Tahar Sfar University Hospital Mahdia
Wafa	Ammari	Tahar Sfar University Hospital Mahdia
Riadh	Massaoud	Tahar Sfar University Hospital Mahdia

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