Do bilateral optic nerve sheath meningiomas exist?

All patients examined at The National Hospital for Nervous Diseases, Queen Square, from 1983 to 1987 with radiological evidence of meningiomas involving both optic nerves within the orbits have been reviewed. Their clinical and X-ray computed tomography (CT) features are different from those of patients with unilateral tumours, and they appear to form a separate group, probably representing optic nerve involvement by a primarily retro-orbital meningioma.