Impact of 5-aminolevulinic acid fluorescence-guided surgery on the extent of resection of meningiomas - With special regard to high-grade tumors

摘要

Background and objectives: In high-grade meningiomas and a subgroup of clinically aggressive benign meningiomas tumor control is still insufficient. Recently 5-ALA fluorescence in meningiomas was reported. The impact of 5-ALA fluorescence-guided surgery (FGS) on surgical decision-making and extent of resection has not yet been systematically analyzed, especially not in high-grade meningiomas. The present study deals with three main questions regarding 5-ALA FGS in meningiomas: to assess the potential for discriminating different WHO grades intra-operatively, to analyze the influence on surgical strategy and to evaluate the impact on extent of resection. Methods: Data from 31 meningiomas operated with 5-ALA FGS were retrospectively analyzed. Intraoperative fluorescence was graded by the surgeon as "no", "low" or "high". Correlations between semi-quantitative fluorescence and histological features (WHO grade) were analyzed. The influence of 5-ALA fluorescence on surgical strategy and the impact of 5-ALA FGS on degree of resection (Simpson grade and post-operative imaging) Were studied. In tumors showing infiltrative growth the extent of resection of fluorescence positive tissue was evaluated. Results: The population comprised 19 WHO grade Ⅰ, 8 grade Ⅱ and 4 grade Ⅲ tumors (61% benign and 39% high-grade meningiomas). 94% of the tumors showed positive fluorescence. Different fluorescence intensities were observed: "no" in two, "high" in 12 and "low" in 17 tumors, respectively. A significant correlation between fluorescence intensity and WHO grade was found (ρ = 0.557, ρ = 0.001). 5-ALA improved the extent of resection in 3/16 (19%) of grade Ⅰ and in 6/8 (75%) of grade Ⅱ/Ⅲ meningiomas. This improvement was not measurable by the Simpson grading as rated by the surgeon and controlled on post-operative imaging.Conclusions: In the present population a strong correlation between fluorescence intensity and WHO grade was observed. 5-ALA FGS improved the extent of resection in meningiomas. Especially in high-grade tumors additional information on brain and neurovascular infiltration was provided. The improved resection was not measurable by Simpson's grading necessitating an additional item, which rates residual fluorescence. Long-term studies are necessary to evaluate a possible impact of FGS on recurrence and overall survival.