A. Hajjaji, S.Sadiki, A. Bouzidi, A. El Ouafi
Journal: Medpeer Publisher
ISSN: 3066-2737
Volume: 3
Issue: 10
Date of Publication: 2026/10/12
Introduction: Optic nerve sheath meningioma (ONSM) is a rare benign tumor arising from the arachnoid cap cells surrounding the optic nerve. Although its course is usually slow, it is a serious cause of progressive visual loss because of its location in the confined orbital space. It is uncommon in young adults, in whom it may follow a more aggressive course.
Clinical case: We report the case of a 25-year-old man who presented with rapidly progressive visual loss and ocular deviation of the left eye. Examination showed a best-corrected distance visual acuity of 1/10 in the left eye, exotropia, a normal anterior segment, and diffuse pallor of the optic disc. Orbito-cerebral computed tomography (CT) revealed a focal fusiform thickening of the intraorbital optic nerve, 10.7 mm in size, involving its lateral aspect, with homogeneous contrast enhancement and punctate calcifications. Magnetic resonance imaging (MRI) showed an iso-intense nerve on T1-weighted images and slight hyperintensity on T2-weighted images; after gadolinium injection, the central nerve appeared hypointense surrounded by a markedly enhancing lateral thickening, consistent with the "tram-track" sign. The diagnosis of intraorbital ONSM was made on imaging alone, without biopsy. Because of the tumor's adherence to the optic nerve and the high risk of postoperative blindness, the patient was referred to radiotherapy.
Conclusion: ONSM should be considered in any young patient with unexplained visual loss, even when the presenting sign is an ocular deviation. MRI is the key diagnostic tool, and fractionated stereotactic radiotherapy is the treatment of choice for progressive forms.
optic nerve sheath meningioma; exotropia; tram-track sign; magnetic resonance imaging; stereotactic radiotherapy; young adult
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