Optic Nerve Pathway Gliomas and Optic Nerve Meningiomas

Abstract

Optic pathway gliomas are intrinsic slow-growing brain tumors that are the most common primary neoplasms of the optic pathways. Optic pathway gliomas are associated with neurofibromatosis type 1; the incidence of optic nerve glioma in patients with this syndrome varies from 8% to 31%. Sporadic optic pathway gliomas present with visual symptoms, the most common of which is decreased visual acuity, but only half of patients with syndromic tumors develop tumor-related signs or symptoms. The optimal treatment of optic pathway gliomas is controversial; options include observation; surgery with clear margins; radiotherapy; and chemotherapy. In general, optic pathway gliomas tend to be low grade and slow growing and associated with long patient survival. Optic nerve sheath meningiomas represent 1% to 2% of all meningiomas and are seen in approximately one quarter of patients with neurofibromatosis type 2. Only 10% of optic nerve sheath meningiomas are primary (arising from the arachnoid villi surrounding the intraorbital or intracanalicular portions of the optic nerves); the remaining 90% are secondary (arising intracranially). The hallmark of optic nerve sheath meningiomas is slowly progressive vision loss. Treatment is conservative, because these tumors usually grow very slowly. Meningiomas are compatible with good vision for many years and are not life threatening.