879 Monitoring Flash Visual Evoked Potentials During Endoscopic Skull Base Surgery Reduces the Risk of Visual Pathway Injury

Abstract

INTRODUCTION: Minimally invasive endoscopic endonasal skull base surgery offer safer and more effective access to the skull base to remove benign and malignant tumors. However, endoscopic skull base surgery around the visual pathway may increase the risk of injury of the visual pathway. Monitoring of flash visual evoked potentials (FVEPs) during surgery may detect a possible injury to the visual pathway, allowing the surgeon to take corrective measures during surgery to reverse or minimize it. METHODS: We identified patients with chiasmatic or pre-chiasmatic lesions who underwent minimally invasive endoscopic skull base surgery. Patients were subjected to eye exam (color vision, visual acuity, and visual field evaluation) within 3 months before surgery, and within 6-12 weeks and 6-9 months after surgery to explore short- and long-term surgical outcomes on eyesight. During surgery, FVEPs were recorded from electrodes placed in the scalp overlying the visual cortex after flashing red light stimulation (Cadwell LED stimulating goggles), as reported previously. We examined the relationship between FVEPs amplitude change and visual outcome on these patients. RESULTS: 102 patients have been enrolled in this retrospective study. The median age at admission was 57 years (range: 22-86 years) and 68.4% of the patients were female. Most of the patients had either pituitary adenoma (64.7%) or skull base meningioma (23.5%). Preliminary eye evaluations (pre- and post-surgery) showed that the patients did not develop short- or long-term eyesight impairments. CONCLUSIONS: Our study provides a new method for rapidly acquiring reproducible FVEP waves for which allows for timely reporting significant FVEP changes resulting in prompt signal action. Thus, monitoring FVEPs during endoscopic endonasal skull base surgery reduces the risk of visual pathway injury.