Salvage Radiosurgery for Optic Nerve Sheath Meningioma

Optic nerve sheath meningiomas (ONSMs) are rare and benign tumors that affect the optic nerve. Although surgical decompression may be used for large tumors that cause mass effect on the surrounding structures, the mainstay of treatment is radiotherapy. We report the case of a 54-year-old female patient who presented with progressive vision loss due to a recurrent right ONSM despite fractionated radiotherapy eight years prior and the subsequent interval regression of the tumor. The optical coherence tomography at the time of recurrence revealed thinning of the right retinal nerve fiber layer. She underwent salvage stereotactic radiosurgery using a marginal dose of 15 Gy. At six months post-radiosurgery, the patient had a dramatic improvement in visual acuity and visual fields despite persistent thinning of the retinal nerve fiber layer. This case illustrates how salvage radiosurgery can be a useful treatment modality in these challenging situations. This tumor's exophytic growth and the steep dose fall-off of Gamma Knife radiosurgery might favorably affect visual recovery. However, the outcomes of single-session radiosurgery for ONSMs should be further evaluated.