RADIATION OPTIC NEUROPATHY AFTER STEREOTAXIC RADIOSURGERY

Purpose: The purpose of the study is to report the occurrence of optic neuropathy after stereotactic radiosurgery for perichiasmal tumors. M ethods: Records of four patients with visual deterioration after stere otactic radiosurgery were reviewed, including clinical findings, neuro imaging results, and treatment methods. Results: Optic neuropathy deve loped 7 to 30 months after gamma knife radiosurgery. All patients expe rienced an abrupt change in visual function, Clinical findings indicat ed anterior visual pathway involvement. Patterns of field loss include d nerve fiber bundle and homonymous hemianopic defects. Gadolinium-enh anced magnetic resonance imaging (MRI) showed swelling and enhancement of the affected portion of the visual apparatus in three patients. Sy stemic corticosteroids were administered in all patients and one parti ally recovered, One patient also received hyperbaric oxygen without im provement. Conclusions: Although rare, optic neuropathy may follow rad iosurgery to lesions near the visual pathways. Careful dose planning g uided by MRI with restriction of the maximal dose to the visual pathwa ys to less than 8 Gy will likely reduce the incidence of this complica tion.