Optic Nerve Sheath Meningioma

SB is a 40-year-old woman who noted some reduction in vision in her left eye during pregnancy. Examination was performed and found visual acuity OD of 20/20 and OS of 20/40-1. A 1+ afferent pupil defect was present in the left eye and Hertel exophthalmometry showed 2 mm of proptosis on that side. Fundus examination on the left found slight pallor of the optic disc with a possible retinochoroidal “shunt” vessel at the inferior margin. It was considered inadvisable to do CT scanning, with its attendant radiation exposure, during her pregnancy. She was given the option for an MRI scan but did not want to risk the unknown effects of a strong magnetic field on her developing fetus and was referred for echography.