Optic nerve sheath meningioma: a case report

Abstract

A case of a 75-year old male with right-sided exopthalmos is presented. Outside proptosis of the right eye was initially observed 6 years ago. Opthalmological and endocrinological clinical examination as well as laboratory tests revealed no pathology from optic nerve disc, optic bulb and thyroid related hormones. MRI study demonstrated an optic nerve meningioma. The key imaging findings and the differential diagnosis were discussed in this present paper. Case presentationA 75-year old male presents to our department with rightsided exopthalmos. Outside proptosis of the right orbital bulb in comparison with the left was initially observed 6 years ago. The patient visited an ophthalmologist and endocrinologist. Fundoscopic examination revealed no atrophy or oedema of the optic disc and no lesion of the optic bulb. Thyroid related hormones were measured within normal limits. The patient did not proceed to any imaging examinations and returned home. He was under steroid treatment with no response and comes to the hospital nowadays still presenting the same painless symptom (exopthalmos with no prominent change), however claiming visual colour disturbance. Fundoscopy and thyroid hormones still revealed no abnormal findings. MRI study of the orbital cavities was performed. In the MRI protocol T2, T2 with fat saturation, T1, T1 with fat saturation sequences, pre-and post gadolinium injection on axial, sagital and coronal planes were performed. A tubular mass was demonstated in the right orbit showing widening along the length of the nerve sheath and an anterior nerve expansion towards the globe. The mass appeared as isointense to brain and optic nerve tissue on T1 weighted images ( Fig. 1) and slightly hyperintense on T2 weighted images (Fig. 2). On T1 weighted images with fat saturation after intravenous administration of paramagnetic substance (gadolinium) the mass presented a homogeneous intense enhancement suggesting in appearance a "tram track" around the hypointense optic nerve (Fig. 3). There is no intracranial extension of the lesion (Fig. 1) or any evidence of surrounding structures invasion (Fig. 3). The presence of optic nerve sheath meningioma was assumed.

Optic Nerve Sheath Meningioma: A Case Report with 15-Year Follow-Up

“…1,8 Lesions may be unilateral, bilateral (6%) or mulitifocal. They usually involve the optic nerve in the orbit but may extend into the intracranial space.…”

“…10 Proptosis and decreased visual acuity are more common in primary than secondary meningiomas. 6,8 Blurred vision reveals depression of the visual field, and dim vision is caused by compression of the optic nerve by the great mass of the apex. The reduction in visual acuity leads to reduced sensitivity to light or projected light, and in some cases to complete insensitivity to light.…”

“…Main lesions included in the differential diagnosis are optic glioma, orbital pseudotumor, and lymphoma. 8 Standard radiographs are usually not diagnostic, unless end-stage enlargement of the optic canal or hyperostosis is present. CT with contrast is an excellent imaging technique for detecting and evaluating ONSMs.…”

“…Primary meningiomas give rise to secondary tumors in 70% of cases. 1,2,8 PREVALENCE Meningiomas occur more frequently in women, 2 suggesting a hormonal connection. Indeed, several studies have detected receptors for estrogen and progesterone in meningioma cells.…”

“…1 Optic nerve sheath meningiomas (ONSMs) are primary and secondary meningiomas arising from meningoendothelial cells of the optic nerve. 6,8 ONSMs occur more frequently in middle-aged women. 6-10…”