Image-Guided Stereotactic Radiosurgery for Optic Nerve Sheath Meningiomas

none2noOptic nerve sheath meningiomas (ONSMs) are benign lesions primarily originating from the dural sheath of the optic nerve. Their progressive growth can lead to gradual loss of vision and exophthalmos. Treatment of these lesions is problematic and depends on the degree of visual impairment and proptosis. In patients with preserved vision and no proptosis, conservative management with frequent ophthalmologic and radiological follow-up is usually preferred. When vision begins to fail surgical intervention can be attempted, but it is often of limited success as far as preserving vision is concerned. Radiotherapy has gained an increasing role in the management of these lesions. Conventional radiotherapy has been used both pre-operatively and post-operatively for many years. More recently fractionated stereotactic radiotherapy has been employed as an alternative to surgery, and may be superior in terms of vision preservation. Care must be however exercised due to the proximity of other important radiosensitive structures. Highly conformal treatments modality, such as those provided by radiosurgery, may overcome this issue. Frame-based stereotactic radiosurgery has been rarely used because single-fraction high-dose irradiation of the optic nerve may be associated with loss of vision. New frameless radiosurgery devices, such as the robotic CyberKnife, an image-guided radiosurgery system, can provide the extremely tight conformality and submillimetric accuracy of frame-based systems combined with the possibility of delivering radiation in multiple sessions. Here, the authors review the clinical presentation and management of ONSMs, highlighting the emerging use of hypofractionated radiosurgery to treat these challenging lesions.mixedRomanelli, Pantaleo; Conti, AlfredoRomanelli, Pantaleo; Conti, Alfred