Safety and surgical outcomes of fluorescein sodium use in vestibular schwannoma: experience from 55 consecutive cases

BACKGROUND: Vestibular schwannomas (VSs) are benign tumors of the vestibulocochlear nerve for which surgical resection remains challenging due to the risk of facial and cochlear nerve injury. Fluorescein sodium (FS) has been introduced to enhance intraoperative visualization, but its clinical role in VS surgery is not fully established. OBJECTIVE: To assess the safety of FS and its association with extent of resection and postoperative neurological outcomes in VS surgery. METHODS: We retrospectively analyzed 55 consecutive patients undergoing retrosigmoid VS resection with intraoperative FS administration (5 mg/kg). Tumors were graded according to the Koos classification. Fluorescein uptake was categorized as absent, moderate, or high. Extent of resection was confirmed by postoperative magnetic resonance imaging (MRI). Facial nerve function was assessed using the House-Brackmann scale, hearing outcomes were evaluated using standard audiological criteria, and renal safety was assessed by paired serum creatinine measurements. RESULTS: = 0.029). Facial nerve function improved over long-term follow-up, particularly in patients with moderate and high uptake. Postoperative hearing decline was more frequent in cases with higher uptake and more extensive resections, likely reflecting increased surgical complexity rather than a direct effect of fluorescein. No evidence of nephrotoxicity was observed. CONCLUSIONS: Fluorescein sodium appears to be a safe intraoperative adjunct that enhances visualization during VS surgery. In this descriptive cohort, higher fluorescein uptake was associated with differences in extent of tumor resection and postoperative neurological outcomes. However, given the absence of a non-fluorescein control group, these findings should be interpreted as exploratory and hypothesis-generating rather than evidence of a causal effect of fluorescein on surgical outcomes.