[Optic nerve sheath meningioma. Experience in Lyon with twenty patients]

Meningioma is an unfrequent optic nerve tumor. Clinical symptoms are not specific, and pathology exam not easily accessible. The diagnosis is usually based on imaging findings. We report our experience, based on twenty patients. Most of them were middle-aged women (mean age=47 years old). The optic nerve meningioma (ONM) was often revealed by visual dysfunction. Ophthalmological evaluation was altered in most patients (visual acuity, visual fields, fundi). The gold-standard exam was MRI of the optic nerve, with and without gadolinium, and with fat-sat sequences. Thirty percent of the lesions remain stable without treatment. Functional prognosis has been improved only by conformal fractionated radiotherapy, but indications and modalities remain to be specified.