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

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, p=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.

Calcifying pseudoneoplasms of the neuraxis (CAPNON): clinical features and therapeutic options.

INTRODUCTION: Calcifying pseudoneoplasms of the neuraxis (CAPNON) are rare, slow-growing lesions occurring anywhere in the central nervous system (CNS). Since their first description in 1978, only 39 cases have been reported in the literature. METHODS: The cases of two patients with histopathologically verified diagnoses of CAPNON are presented. Thereafter, we review all reports published so far with respect to study type, number of patients, anatomical area (intracranial, spinal, or both), clinical presentation, radiological presentation, therapy, duration of follow-up, incidence and type of complication, and outcome. Furthermore, current recommendations for the management of spinal and cerebral CAPNON are discussed. RESULTS: A total of 19 retrospective articles were identified and selected for review: 6 case series (31.6 %) and 13 reports of single cases (68.4 %). The 19 articles and our two additional cases added up to a total of 19 patients with spinal CAPNON and 22 patients with intracranial CAPNON. All patients were treated surgically. A follow-up was provided in 13 patients with spinal (68.4 %) and in 16 patients with intracranial CAPNON (72.7 %), respectively. The follow-up showed no signs of recurrence in 12 of 13 patients with spinal CAPNON (92.3 %) and in 15 of 16 patients with intracranial CAPNON (93.7 %). One-tailed Fisher's exact test revealed no significant difference between complete and incomplete resection in terms of disease recurrence (spinal: p = 0.6842; intracranial: p = 0.3749). Analysis of the literature did not reveal any deaths directly associated with CAPNON. CONCLUSIONS: Calcifying pseudoneoplasms are rare benign lesions of the CNS of yet unknown origin. Because of the increasing number of reports, this clinical entity should be taken into consideration in the differential diagnosis of intracranial and intraspinal calcified lesions.