Walsh & Hoyt: Meningiomas

Anterior compressive optic neuropathy may result from primary optic nerve sheath meningiomas (ONSM). The tumors arise from meningiothelial cells in the arachnoid villi. Optic nerve sheath meningiomas surround the optic nerve and result in impaired axonal transport (leading to disc swelling) and also interfere with the pial blood supply to the optic nerve. The tumor occurs most commonly in middle-aged women and is usually unilateral. Patients present with slowly progressive vision loss, mild proptosis, double vision, transient visual obscurations, and gaze-evoked amaurosis. Examination reveals a color vision defect, afferent pupillary defect, and visual field defects including central scotomas, enlarged blind spots, and generalized constriction. The optic nerve appears abnormal with either optic atrophy and or with disc edema. Optociliary collateral vessels may be present and are seen in both swollen and atrophic nerves.