Surgical Resection of an Optic Nerve Sheath Meningioma: Relevance of Endoscopic Endonasal Approaches to the Optic Canal

Optic nerve sheath meningiomas (ONSMs) account for less than 2% of meningiomas and 1.7% of orbital tumors. Although rare, the management of these tumors is important as unilateral blindness often results in untreated cases. Radiotherapy has emerged as the preferred treatment. However, therapies for ONSMs are controversial due to the variable natural history of the disease and limitations of surgical and radiotherapy options. A 60-year-old woman presented with monocular left diminished color perception and blurred vision. Magnetic resonance imaging demonstrated a homogenously enhancing 5-mm left optic nerve mass with evidence of nerve compression. Conservative management was advised. However, 1 month after diagnosis her visual acuity deteriorated further. Because of the small focal location of the tumor within the optic canal, surgery was considered. Given the tumor's location inferomedial to the optic nerve, an endoscopic endonasal approach to the optic canal was performed. This patient recovered fully with resolution of visual symptoms immediately following surgery. Postoperative imaging 24 hours after surgery demonstrated gross total resection of the tumor; 1 year postoperatively the patient has a normal ophthalmologic examination. This report highlights the value of endoscopic endonasal approaches in the management of select optic canal pathology, otherwise inaccessible via transcranial approaches.