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Objective: Atypical and anaplastic meningiomas account for 20% of all meningiomas. An irregular tumor shape on preoperative MRI has been associated with WHO grade II-III histology. However, this subjective allocation does not allow quantification or comparison. An objective parameter of irregularity could substantially influence resection strategy toward a more aggressive approach. Therefore, the aim of this study was to objectively quantify the level of irregularity on preoperative MRI and predict histology based on WHO grade using this novel approach., Methods: A retrospective study on meningiomas resected between January 2010 and December 2018 was conducted at two neurosurgical centers. This novel approach relies on the theory that a regularly shaped tumor has a smaller surface area than an irregularly shaped tumor with the same volume. A factor was generated using the surface area of a corresponding sphere as a reference, because for a given volume a sphere represents the shape with the smallest surface area possible. Consequently, the surface factor (SF) was calculated by dividing the surface area of a sphere with the same volume as the tumor with the surface area of the tumor. The resulting value of the SF ranges from > 0 to 1. Finally, the SF of each meningioma was then correlated with the corresponding histopathological grading., Results: A total of 126 patients were included in this study; 60.3% had a WHO grade I, 34.9% a WHO grade II, and 4.8% a WHO grade III meningioma. Calculation of the SF demonstrated a significant difference in SFs between WHO grade I (SF 0.851) and WHO grade II-III meningiomas (SF 0.788) (p < 0.001). Multivariate analysis identified SF as an independent prognostic factor for WHO grade (OR 0.000009, 95% CI 0.000-0.159; p = 0.020)., Conclusions: The SF is a proposed mathematical model for a quantitative and objective measurement of meningioma shape, instead of the present subjective assessment. This study revealed significant differences between the SFs of WHO grade I and WHO grade II-III meningiomas and demonstrated that SF is an independent prognostic factor for WHO grade.

Objective: Incomplete neurosurgical resection of brain metastases (BM) due to insufficient intraoperative visualization of tumor tissue is a major clinical challenge and might result in local recurrence. Recently, visible 5-aminolevulinic acid (5-ALA) induced fluorescence was first reported in patients with BM. The aim of this study was thus to investigate, for the first time systematically, the value of 5-ALA fluorescence for intraoperative visualization of BM in a large patient cohort., Methods: Adult patients (≥ 18 years) with resection of suspected BM after preoperative 5-ALA administration were prospectively recruited at two specialized neurosurgical centers. During surgery, the fluorescence status (visible or no fluorescence); fluorescence quality (strong, vague, or none); and fluorescence homogeneity (homogeneous or heterogeneous) of each BM was investigated. Additionally, these specific fluorescence characteristics of BM were correlated with the primary tumor type and the histopathological subtype. Tumor diagnosis was established according to the current WHO 2016 criteria., Results: Altogether, 157 BM were surgically treated in 154 patients. Visible fluorescence was observed in 104 BM (66%), whereas fluorescence was absent in the remaining 53 cases (34%). In detail, 53 tumors (34%) showed strong fluorescence, 51 tumors (32%) showed vague fluorescence, and 53 tumors (34%) had no fluorescence. The majority of BM (84% of cases) demonstrated a heterogeneous fluorescence pattern. According to primary tumor, visible fluorescence was less frequent in BM of melanomas compared to all other tumors (p = 0.037). According to histopathological subtype, visible fluorescence was more common in BM of ductal breast cancer than all other subtypes (p = 0.008). It is of note that visible fluorescence was observed in the surrounding brain tissue after the resection of BM in 74 (67%) of 111 investigated cases as well., Conclusions: In this largest series to date, visible 5-ALA fluorescence was detected in two-thirds of BM. However, the characteristic heterogeneous fluorescence pattern and frequent lack of strong fluorescence limits the use of 5-ALA in BM and thus this technique needs further improvements.

Objective: Unilateral evacuation of bilateral chronic subdural hematomas (bcSDHs) is associated with higher retreatment rates than an initial bilateral intervention. One reason for that is a possible progression in the size of the contralateral side after unilateral treatment. Thus, the authors focused their study on finding predictors of the need for contralateral retreatment., Methods: All patients who had undergone unilateral or bilateral evacuation of bcSDHs in the Department of Neurosurgery at the University Hospital of St. Poelten during a 5-year period (7/2012 to 6/2017) were retrospectively identified. The preoperative hematoma volume was calculated using the XYZ/2 method., Results: Of a total of 103 patients with bcSDHs, 61 patients underwent bilateral evacuation and 42 patients underwent unilateral evacuation. The retreatment rate after bilateral evacuation was significantly lower than that after unilateral evacuation (14.8% vs 31%, respectively; p = 0.049). Contralateral retreatment after unilateral evacuation was necessary in 9 patients (21.4%). The preoperative contralateral hematoma volume was significantly higher in those patients who needed contralateral retreatment after initial unilateral evacuation (68.4 cm3 vs 27.4 cm3, respectively; p < 0.001). Furthermore, the so-called volume relation ratio created by dividing the smaller by the larger hematoma volume was significantly higher when contralateral retreatment became necessary (0.56 vs 0.21, respectively; p < 0.001)., Conclusions: Patients needing evacuation of bcSDHs should be considered for primary bilateral evacuation if the hematoma volume on the smaller side is greater than 40 cm3 and the subsequent volume relation ratio is greater than 0.4.