LGG-56. Surgical management of pre-chiasmatic intraorbital optic nerve gliomas in children after loss of visual function – Resection from bulbus to chiasm

INTRODUCTION: Optic pathway gliomas (OPG) in children carry significant morbidity and therapeutic challenges. The subgroup of pre-chiasmatic gliomas manifest with exopthalmus are a subgroup where, after blindness has occurred, an intraorbital and intradural resection is a curative option. We present a two-center cohort using two different surgical approaches and describe indication, technique, and long term surgical outcome. METHODS: A retrospective analysis in both centers was performed to included patients < 18 years at diagnosis with a pre-chiasmatic intra-orbital glioma, in whom a resection from the bulb to the chiasm was performed. RESULTS: 11 patients were included. 4 had NF1. Mean age at surgery was 7.0 years. Interval between diagnosis and surgery was 1-74 (median 10) months. Two had prior chemotherapy, one radiation, one both, one prior intraorbital surgery. In all 5 progression occurred. Indications for surgery were exophthalmos, pain, tumor progression or a combination. 8 patients (Group A) underwent an extradural trans-orbital-roof approach to resect intra-orbital tumour including the optic canal part plus intradural pre-chiasmatic resection. In 3 patients (Group B) a combined supra-orbital mini-craniotomy plus orbital frame osteotomy was used for intraorbital tumour-resection, excluding the optic canal part, plus intradural pre-chiasmatic resection. GTR was achieved in 7/8 of Group A and none had a recurrence (mean-FU 42 month). One residual behind the bulbus showed progression, treated by chemotherapy. All residuals in Group B were remnants of the optic nerve within optic canal remained stable (mean FU 11.8 months). No patient had a chiasmatic functional affection or permanent oculomotor deficits. Two after prior radiotherapy developed slight enophthalmos. CONCLUSION: In these selected patients surgical resection from bulb to chiasm (± removal of optic canal tumor) is safe without long-term sequela and with excellent cosmetic result. Surgery removes immediately exophthalmos and provides an effective long-term tumor control. It should be considered therapy of choice.