[Simulation of anterior ischemic optic neuropathy by optic nerve sheath meningioma].
BACKGROUND: The optic nerve sheath meningioma usually presents with a diffuse atrophy of the disc and a diffuse depression of the visual field. Applying this rule too rigidly can lead to a false diagnosis. PATIENT: A 45y-old-woman presented with atrophy of the upper disc and a corresponding altitudinal field defect in her right eye. AION was diagnosed. Seventeen years later the patient returned with an exophthalmus. The disc was atrophic and a shunt vessel connected the central retinal vein with the choroid. CT revealed an orbital mass. The diagnosis of an optic nerve sheath meningioma was made and confirmed at surgery. DISCUSSION: The meningioma may have occluded an upper posterior ciliary artery, mimiking an AION. Alternatively, the meningioma may have destroyed the fibers running through the upper half of the disc and caused swelling of the remaining fibers in the lower half of the disc. CONCLUSION: In the combination of swelling and atrophy of one disc an optic nerve sheath meningioma should be considered, even if the two components are located in different sectors. In optic nerve sheath meningioma vision decreases insidiously as opposed to the acute drop typical for anterior ischemic optic atrophy.