Diagnosis and treatment of orbital optic nerve sheath meningioma.

BACKGROUND: Primary and secondary optic nerve sheath meningiomas (ONSMs) are neoplasms that account for a large proportion of optic nerve and orbital tumors. The diagnosis is not always straightforward and is based on the appropriate clinical findings and neuroimaging. Biopsy or surgical intervention may occasionally be necessary but is associated with significant morbidity.
METHODS: Issues related to clinical signs and symptoms, diagnosis, natural history, and treatment strategies are reviewed based on a review of published literature.
RESULTS: Diagnosis is usually based on radiographic and clinical findings. Biopsies are not obtained in most cases, thus adding further to the bias of possible misdiagnosis in all reported case series that do not have the benefit of histopathologic confirmation. Natural history typically shows inexorable progression in most cases, although long periods of stability are occasionally reported. Treatment options include observation, radiation alone, surgery alone, and combined radiation and surgery. The optimum timing of interventional therapy and radiation are evolving.
CONCLUSIONS: After serial examination documents new decline in acuity and/or visual field, fractionated radiotherapy appears most likely to preserve visual function and is a valid treatment approach for primary orbital ONSM. Tumor enlargement, as determined by serial imaging, may also provide an indication to begin radiotherapy.