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Background and Objectives: Spheno-orbital meningiomas arise from the arachnoid villi cap cells at the sphenoid ridge and have the ability to spread through soft tissue extension and cranial bone invasion. Owing to their orbital hyperostosis and intraorbital soft tissue extension, they commonly present with ophthalmologic manifestations. This study aims to investigate the correlation between tumor volume with the presenting symptoms and postoperative outcomes., Methods: This retrospective study analyzed patients who underwent surgical resection of spheno-orbital meningiomas. Tumor volumes in different compartments were measured using preoperative and postoperative imaging. Linear and logistic regression analyses were used to identify correlations between tumor volumes and presenting symptoms preoperatively and postoperative outcomes., Results: Sixty-six patients were included in this study, of whom 86.4% had proptosis, 80.3% had decreased visual acuity (VA), 30.3% had visual field defects, and 13.6% had periorbital edema. Preoperatively, proptosis linearly correlated with intraosseous tumor volume (coefficient = 0.6, P < .001), while the decrease in baseline VA correlated with the intraorbital tumor volume (coefficient = 0.3, P = .01). The odds of periorbital edema were found to increase with an increase in intraosseous tumor volume with an adjusted odds ratio of 1.4 (95% CI, 1.1-1.7, P = .003), while the odds of visual field defects were found to increase with an increase in intraorbital tumor volume with an adjusted odds ratio of 2.7 (95% CI, 1.3-5.6, P = .01). Postoperatively, the volume of intraosseous tumor resected linearly correlated with the improvement in proptosis (coefficient = 0.7, P < .001), while the volume of intraorbital tumor resected linearly correlated with improvement in VA (coefficient = 0.5, P < .001) and with a larger effect size in patients presenting with moderate-to-severe decrease in VA preoperatively (coefficient = 0.8)., Conclusion: Underscoring the importance of each tumor compartment relative to the patient's symptomatology serves as a valuable guide in implementing a compartmentalized resection approach tailored to the surgical objectives., (Copyright © Congress of Neurological Surgeons 2023. All rights reserved.)

Background and Objectives: Intracranial meningiomas are a diverse group of tumors, which vary by grade, genetic composition, location, and vasculature. Expanding the understanding of the supply of skull base (SBMs) and non-skull base meningiomas (NSBMs) will serve to further inform resection strategies. We sought to delineate the vascular supply of a series of intracranial meningiomas by tumor location., Methods: A retrospective study of intracranial meningiomas that were studied using preoperative digital subtraction angiograms before surgical resection at a tertiary referral center was performed. Patient, tumor, radiologic, and treatment data were collected, and regression models were developed., Results: One hundred sixty-five patients met inclusion criteria. The mean age was 57.1 years (SD: 12.6). The mean tumor diameter was 4.9 cm (SD: 1.5). One hundred twenty-six were World Health Organization Grade I, 37 Grade II, and 2 Grade III. Arterial feeders were tabulated by Al-Mefty's anatomic designations. SBMs were more likely to derive arterial supply from the anterior circulation, whereas NSBMs were supplied by external carotid branches. NSBMs were larger (5.61 cm vs 4.45 cm, P = <.001), were more often presented with seizure (20% vs 8%, P = .03), were higher grade ( P = <.001) had more frequent peritumoral brain edema (84.6% vs 66%, P = .04), and had more bilateral feeders (47.7% vs 28%, P = .01) compared with SBMs. More arterial feeders were significantly associated with lower tumor grade ( P = .023, OR = 0.59). Higher tumor grade (Grade II/III) was associated with fewer arterial feeders ( P = .017, RR = 0.74)., Conclusion: Meningioma location is associated with specific vascular supply patterns, grade, and patient outcomes. This information suggests that grade I tumors, especially larger tumors, are more likely to have diverse vascular supply patterns, including internal carotid branches. This study may inform preoperative embolization and surgical considerations, particularly for large skull base tumors., (Copyright © Congress of Neurological Surgeons 2023. All rights reserved.)

Background: For patients with either an incompletely resected meningioma or recurrence after surgery, stereotactic radiosurgery is frequently used. MRI is typically used for stereotactic radiosurgery targeting, but differentiating tumor growth from postoperative change can be challenging. 68 Ga-DOTATATE, a positron emission tomography (PET) radiotracer targeting the somatostatin receptor type 2, has been shown to be a reliable meningioma biomarker., Objective: To evaluate the impact of 68 Ga-DOTATATE on treatment planning in patients who had previously undergone meningioma resection., Methods: We present a consecutive case series of 12 patients with pathology-proven meningioma who received a 68 Ga-DOTATATE PET between April 2019 and April 2021. Treatment planning was performed first using MRI. DOTATATE-PET images were then used to assess accurate tumor identification., Results: Ten patients had WHO Grade 2 meningioma, and 2 patients had Grade 1 tumor. Eight patients had recurrent meningiomas, and 4 patients had newly diagnosed disease. Overall, 68 Ga-DOTATATE PET scans altered previously formulated treatment plans in 5 of 12 patients. In addition, 9 of 12 patients had disease foci not appreciated on MRI., Conclusion: In this series, incorporating 68 Ga-DOTATATE PET imaging had clinical utility for most patients in whom it was used. It proved particularly adept in demonstrating intraosseous meningiomas, differentiating recurrence from postoperative changes, and identifying subcentimeter disease foci. It is an imaging modality that our center will continue to use as a means of improving postoperative treatment plans after the surgical resection of meningiomas., (Copyright © Congress of Neurological Surgeons 2023. All rights reserved.)

Background: Stereotactic radiosurgery (SRS) is an effective adjuvant therapy for residual tumor after subtotal resection of parasellar meningiomas. Fat graft placement between the optic nerve/chiasm and residual tumor (optic neuropexy [OPN]) allows for safe SRS therapy., Objective: To evaluate the radiological temporal profile of the fat graft after OPN, immediately after surgery and at 3, 6, and 12 months intervals, to elucidate the optimal time point of adjuvant SRS., Methods: A single-center, retrospective, cohort study of 23 patients after surgery for parasellar meningioma was conducted. Fat graft volume and MRI signal ratios were calculated. SRS dosimetric parameters (tumor/optic nerve) were measured at the time of SRS and compared with a hypothetical dosimetric plan based on an early postoperative MRI., Results: Of 23 patients, 6 (26%) had gross total resection and 17 (74%) had subtotal resection. Fat grafts showed a progressive loss of volume and signal ratio over time. Radiosurgery was performed in 14 (82.3%; 8 hypofractionated radiosurgery and 6 single fraction). At 3 months, there is a loss of 46% of the fat volume and degradation of its tissue intensity, decreasing differentiation from tumor and nerve. The hypothetical treatment plan (performed on an early postoperative MRI) showed that single-fraction SRS would have been possible in 6 of the 8 hypofractionated cases., Conclusion: OPN is a technique that can be safely performed after resection of parasellar meningiomas. Because of the reduction of the fat volume and tissue differentiation between fat and tumor/nerves, adjuvant radiosurgery is better performed within the first 3 months after surgery., (Copyright © 2023 The Author(s). Published by Wolters Kluwer Health, Inc. on behalf of the Congress of Neurological Surgeons.)

Background: After meningioma surgery, approximately 1 in 3 patients will have residual tumor that requires ongoing imaging surveillance. The precise volumetric growth rates of these tumors are unknown., Objective: To identify the volumetric growth rates of residual meningioma, growth trajectory, and factors associated with progression., Methods: Patients with residual meningioma identified at a tertiary neurosurgery center between 2004 and 2020 were retrospectively reviewed. Tumor volume was measured using manual segmentation, after surgery and at every follow-up MRI scan. Growth rates were ascertained using a linear mixed-effects model and nonlinear regression analysis of growth trajectories. Progression was defined according to the Response Assessment in Neuro-Oncology (RANO) criteria (40% volume increase)., Results: There were 236 patients with residual meningioma. One hundred and thirty-two patients (56.0%) progressed according to the RANO criteria, with 86 patients being conservatively managed (65.2%) after progression. Thirteen patients (5.5%) developed clinical progression. Over a median follow-up of 5.3 years (interquartile range, 3.5-8.6 years), the absolute growth rate was 0.11 cm 3 per year and the relative growth rate 4.3% per year. Factors associated with residual meningioma progression in multivariable Cox regression analysis were skull base location (hazard ratio [HR] 1.60, 95% CI 1.02-2.50) and increasing Ki-67 index (HR 3.43, 95% CI 1.19-9.90). Most meningioma exhibited exponential and logistic growth patterns (median R 2 value 0.84, 95% CI 0.60-0.90)., Conclusion: Absolute and relative growth rates of residual meningioma are low, but most meet the RANO criteria for progression. Location and Ki-67 index can be used to stratify adjuvant treatment and surveillance paradigms., (Copyright © 2022 The Author(s). Published by Wolters Kluwer Health, Inc. on behalf of the Congress of Neurological Surgeons.)

Background: Accurate specimen analysis of skull base tumors is essential for providing personalized surgical treatment strategies. Intraoperative specimen interpretation can be challenging because of the wide range of skull base pathologies and lack of intraoperative pathology resources., Objective: To develop an independent and parallel intraoperative workflow that can provide rapid and accurate skull base tumor specimen analysis using label-free optical imaging and artificial intelligence., Methods: We used a fiber laser-based, label-free, nonconsumptive, high-resolution microscopy method (<60 seconds per 1 × 1 mm2), called stimulated Raman histology (SRH), to image a consecutive, multicenter cohort of patients with skull base tumor. SRH images were then used to train a convolutional neural network model using 3 representation learning strategies: cross-entropy, self-supervised contrastive learning, and supervised contrastive learning. Our trained convolutional neural network models were tested on a held-out, multicenter SRH data set., Results: SRH was able to image the diagnostic features of both benign and malignant skull base tumors. Of the 3 representation learning strategies, supervised contrastive learning most effectively learned the distinctive and diagnostic SRH image features for each of the skull base tumor types. In our multicenter testing set, cross-entropy achieved an overall diagnostic accuracy of 91.5%, self-supervised contrastive learning 83.9%, and supervised contrastive learning 96.6%. Our trained model was able to segment tumor-normal margins and detect regions of microscopic tumor infiltration in meningioma SRH images., Conclusion: SRH with trained artificial intelligence models can provide rapid and accurate intraoperative analysis of skull base tumor specimens to inform surgical decision-making., (Copyright © Congress of Neurological Surgeons 2022. All rights reserved.)

Background: Although World Health Organization (WHO) grade I meningiomas are considered "benign" tumors, an elevated Ki-67 is one crucial factor that has been shown to influence tumor behavior and clinical outcomes. The ability to preoperatively discern Ki-67 would confer the ability to guide surgical strategy., Objective: In this study, we develop a machine learning (ML) algorithm using radiomic feature analysis to predict Ki-67 in WHO grade I meningiomas., Methods: A retrospective analysis was performed for a cohort of 306 patients who underwent surgical resection of WHO grade I meningiomas. Preoperative magnetic resonance imaging was used to perform radiomic feature extraction followed by ML modeling using least absolute shrinkage and selection operator wrapped with support vector machine through nested cross-validation on a discovery cohort (n = 230), to stratify tumors based on Ki-67 <5% and ≥5%. The final model was independently tested on a replication cohort (n = 76)., Results: An area under the receiver operating curve (AUC) of 0.84 (95% CI: 0.78-0.90) with a sensitivity of 84.1% and specificity of 73.3% was achieved in the discovery cohort. When this model was applied to the replication cohort, a similar high performance was achieved, with an AUC of 0.83 (95% CI: 0.73-0.94), sensitivity and specificity of 82.6% and 85.5%, respectively. The model demonstrated similar efficacy when applied to skull base and nonskull base tumors., Conclusion: Our proposed radiomic feature analysis can be used to stratify WHO grade I meningiomas based on Ki-67 with excellent accuracy and can be applied to skull base and nonskull base tumors with similar performance achieved., (© Congress of Neurological Surgeons 2021.)

Background: Stereotactic radiosurgery (SRS) is increasingly considered for selected olfactory groove meningiomas (OGMs)., Objective: To investigate the safety and efficacy of SRS for OGMs., Methods: From 20 institutions participating in the International Radiosurgery Research Foundation, we pooled patients who underwent SRS for histologically confirmed or radiologically suspected WHO grade I OGMs and were followed for 6 mo or more after the SRS., Results: In total, 278 (median age 57 yr) patients underwent SRS for histologically confirmed (29%) or radiologically suspected (71%) WHO grade I OGMs Median treatment volume was 4.60 cm3 (range: 0.12-27.3 cm3), median prescription dose was 12 Gy, and median dose to the olfactory nerve was 11.20 Gy. During median post-SRS imaging follow-up of 39 mo (range: 6-240 mo), 43% of patients had partial or marginal response, 54% of patients had stable disease, and 3% of patients experienced progression. During median post-SRS clinical follow-up of 51 mo (range: 6-240 mo), 36 (13%) patients experienced clinical and/or radiological adverse radiation events (AREs). Elevated risk of AREs was associated with larger OGM volume (P = .009) and pre-SRS peritumoral T2/fluid-attenuated inversion-recovery signal abnormalities (P < .001). After the SRS, olfaction remained stable, improved, or deteriorated in 90%, 8%, and 2% of patients, respectively. Complete post-SRS anosmia was predicted by partial/complete anosmia before the SRS (odds ratio [OR] = 83.125; 95% CI [24.589-281.01], P < .001) and prior resection of OGM (OR = 3.919; 95% CI [1.713-8.970], P = .001)., Conclusion: SRS is associated with durable local control of the majority of OGM patients with acceptable safety profile. SRS allows preservation or improvement of olfactory function in the majority of OGM patients., (© Congress of Neurological Surgeons 2021.)

Background: The behavior of meningiomas under influence of progestin therapy remains unclear., Objective: To investigate the relationship between growth kinetics of intracranial meningiomas and usage of the progestin cyproterone acetate (PCA)., Methods: This study prospectively followed 108 women with 262 intracranial meningiomas and documented PCA use. A per-meningioma analysis was conducted. Changes in meningioma volumes over time, and meningioma growth velocities, were measured on magnetic resonance imaging (MRI) after stopping PCA treatment., Results: Mean follow-up time was 30 (standard deviation [SD] 29) mo. Ten (4%) meningiomas were treated surgically at presentation. The other 252 meningiomas were followed after stopping PCA treatment. Overall, followed meningiomas decreased their volumes by 33% on average (SD 28%). A total of 188 (72%) meningiomas decreased, 51 (20%) meningiomas remained stable, and 13 (4%) increased in volume of which 3 (1%) were surgically treated because of radiological progression during follow-up after PCA withdrawal. In total, 239 of 262 (91%) meningiomas regressed or stabilized during follow-up. Subgroup analysis in 7 women with 19 meningiomas with follow-up before and after PCA withdrawal demonstrated that meningioma growth velocity changed statistically significantly (P = .02). Meningiomas grew (average velocity of 0.25 mm3/day) while patients were using PCA and shrank (average velocity of -0.54 mm3/day) after discontinuation of PCA., Conclusion: Ninety-one percent of intracranial meningiomas in female patients with long-term PCA use decrease or stabilize on MRI after stopping PCA treatment. Meningioma growth kinetics change significantly from growth during PCA usage to shrinkage after PCA withdrawal., (© Congress of Neurological Surgeons 2021.)

Background: Surgeon's intraoperative estimation of meningioma extent of resection (Simpson Grade, SG) is widely used as a prognostic factor for recurrence. However, the validity of SG is still a matter of debate. In preoperative imaging, 68Ga-DOTATATE/PET-CT has been shown to detect meningioma tissue even more sensitively than magnetic resonance imaging (MRI)., Objective: To evaluate the Simpson grading within the framework of modern postoperative imaging techniques (MRI; PET-CT)., Methods: At first, patients with WHO grade I meningioma, surgical resection, and postoperative 68Ga-DOTATATE/PET-CT within 6 mo after surgery were retrospectively analyzed. Second, an analogous prospective cohort of patients with WHO grade I meningioma was investigated by comparing SG after meningioma removal with postoperative MRI and 68Ga-DOTATATE/PET-CT within 6 mo after surgery., Results: A total of 37 patients were retrospectively analyzed. In total, 5/8 patients with SG-I and II resections showed tumor remnants according to postoperative PET-CT (SG 62.5% false negative). In the prospective cohort of 52 tumors, PET-CT displayed tracer uptake in 15/37 SG-I or II resections indicating unexpected tumor remnants (SG 40.5% false negative). MRI was false negative in 7 of these 15 cases (MRI 18.9% false negative) (P = .037). Discordant results according to PET-CT were more often found in convexity (40%) and falcine (46.7%) meningiomas than in skull base meningiomas (18.2%)., Conclusion: Intraoperative Simpson grading is at risk to underestimate tumor remnants, predominantly in grade I and II resections. Postoperative PET-CT improves detection rates compared to MRI. Prognostic impact of postoperative meningioma remnants according to PET-CT needs to be investigated prospectively., (Copyright © 2020 by the Congress of Neurological Surgeons.)

Background: An increased incidence of various neoplasms has been described in patients with acromegaly, and there is evidence to suggest that growth factors are risk factors for the development of meningiomas., Objective: To study if patients with acromegaly are more at risk for developing intracranial meningiomas., Methods: We conducted an observational study on 221 consecutive acromegalic patients recruited between January 1, 2000 and December 31, 2015, and 357 consecutive patients with a nonsomatotropic pituitary adenoma recruited between March 1, 2015 and December 31, 2016, in our institution. Patients underwent a gadolinium-enhanced 3D T1 brain magnetic resonance imaging to look for meningiomas. The proportion of meningiomas was compared between the 2 groups, and the standardized incidence ratio (SIR) was computed from the incidence rates of meningiomas observed in the population of acromegalic patients and compared to that of the general population given by the local registry of central nervous system tumors., Results: Patients with acromegaly had a significant risk for developing intracranial meningiomas as compared to patients without acromegaly (7.7% vs 2.2%, P = .005, OR = 3.45 [1.46; 8.15]). There was a significant increased incidence of intracranial meningiomas in patients with acromegaly (SIR = 126 [25; 367]) as compared to the general population., Conclusion: Our study suggests strongly that patients with acromegaly are more at risk for developing intracranial meningiomas., (Copyright © 2019 by the Congress of Neurological Surgeons.)

Background: Some patients are diagnosed with asymptomatic meningioma(s) after undergoing a screening CT and MRI for minor ailments or postresection., Objective: To help clinicians in decision making for treatment of asymptomatic meningiomas., Methods: A single center retrospective cohort study of 117 patients with 122 tumors treated with Gamma Knife radiosurgery (GKRS; Elekta AB, Stockholm, Sweden). Patients were followed with longitudinal imaging and clinical evaluations. Tumor volumetry and developments of new signs or symptoms after GKRS were the end points in the study., Results: Median patient age at GKRS was 60 yr (range 21-86 yr) with a median clinical follow-up of 53 mo (range 20-252 mo). The median pre-GKRS tumor volume was 3.6 ± 3.8 cc (±standard deviation). Tumors were treated with a median margin dose of 14 ± 2 Gy. At last follow-up, median tumor volume was 2.5 ± 3.6 cc. Radiological progression-free survival (PFS) rates were 97% and 94.4% at 5 yr and 10 yr, respectively. Clinical PFS rates were 86% and 70% at 5 yr and 10 yr, respectively. Development of neurological complications was seen in 21 (18%) patients, and 11 (52%) of them had undergone surgical resection prior to GKRS., Conclusion: GKRS is a reasonable treatment strategy for asymptomatic meningiomas and compares favorably to natural history studies in terms of tumor control and neurological preservation. It results in relatively low morbidity in previously untreated meningiomas and serves as an appealing alternative treatment modality for recurrent meningiomas in asymptomatic patients., (Copyright © 2019 by the Congress of Neurological Surgeons.)

Background: Brain metastases (BM) treated with surgical resection and focal postoperative radiotherapy have been associated with an increased risk of subsequent leptomeningeal dissemination (LMD). BMs with hemorrhagic and/or cystic features contain less solid components and may therefore be at higher risk for tumor spillage during resection., Objective: To investigate the association between hemorrhagic and cystic BMs treated with surgical resection and stereotactic radiosurgery and the risk of LMD., Methods: One hundred thirty-four consecutive patients with a single resected BM treated with adjuvant stereotactic radiosurgery from 2008 to 2016 were identified. Intracranial outcomes including LMD were calculated using the cumulative incidence model with death as a competing risk. Univariable analysis and multivariable analysis were assessed using the Fine & Gray model. Overall survival was analyzed using the Kaplan-Meier method., Results: Median imaging follow-up was 14.2 mo (range 2.5-132 mo). Hemorrhagic and cystic features were present in 46 (34%) and 32 (24%) patients, respectively. The overall 12- and 24-mo cumulative incidence of LMD with death as a competing risk was 11.0 and 22.4%, respectively. On multivariable analysis, hemorrhagic features (hazard ratio [HR] 2.34, P = .015), cystic features (HR 2.34, P = .013), breast histology (HR 3.23, P = .016), and number of brain metastases >1 (HR 2.09, P = .032) were independently associated with increased risk of LMD., Conclusion: Hemorrhagic and cystic features were independently associated with increased risk for postoperative LMD. Patients with BMs containing these intralesion features may benefit from alternative treatment strategies to mitigate this risk., (Copyright © 2018 by the Congress of Neurological Surgeons.)

Background and Importance: Cavernous angiomas or cavernomas are vascular malformations usually located in the brain parenchyma. However, they rarely present as extra-axial lesions, attached to the dura, and may mimic meningiomas. Most reported cases concern the cavernous sinus region and other locations are very uncommon., Clinical Presentation: A 61-yr-old female known for long-standing mental illness presented with progressive gait instability. Imaging studies revealed an extra-axial lesion in relation to the anterior part of the falx cerebri. An interhemispheric approach was used to remove the lesion. Pathological analysis revealed features compatible with an extra-axial cavernoma: structureless vascular channels lacking smooth muscle and elastic lamellae, without intervening brain parenchyma., Conclusion: Cavernous angiomas or cavernomas can present as extra-axial lesions. Although progressive growth can be observed, they should not be considered as tumoral lesions, because there is no cellular duplication. Unlike other locations, resection of anterior cranial fossa extra-axial cavernomas seems to be facilitated by minimal bleeding., (Copyright © 2018 by the Congress of Neurological Surgeons.)

Background: Sphenoid wing meningiomas (SWMs) can encase arteries of the circle of Willis, increasing their susceptibility to intraoperative vascular injury and severe ischemic complications., Objective: To demonstrate the effect of circumferential vascular encasement in SWM on postoperative ischemia., Methods: A retrospective review of 75 patients surgically treated for SWM from 2009 to 2015 was undertaken to determine the degree of circumferential vascular encasement (0°-360°) as assessed by preoperative magnetic resonance imaging (MRI). A novel grading system describing "maximum" and "total" arterial encasement scores was created. Postoperative MRIs were reviewed for total ischemia volume measured on sequential diffusion-weighted images., Results: Of the 75 patients, 89.3% had some degree of vascular involvement with a median maximum encasement score of 3.0 (2.0-3.0) in the internal carotid artery (ICA), M1, M2, and A1 segments; 76% of patients had some degree of ischemia with median infarct volume of 3.75 cm 3 (0.81-9.3 cm 3 ). Univariate analysis determined risk factors associated with larger infarction volume, which were encasement of the supraclinoid ICA ( P < .001), M1 segment ( P < .001), A1 segment ( P = .015), and diabetes ( P = .019). As the maximum encasement score increased from 1 to 5 in each of the significant arterial segments, so did mean and median infarction volume ( P < .001). Risk for devastating ischemic injury >62 cm 3 was found when the ICA, M1, and A1 vessels all had ≥360° involvement ( P = .001). Residual tumor was associated with smaller infarct volumes ( P = .022). As infarction volume increased, so did modified Rankin Score at discharge ( P = .025)., Conclusion: Subtotal resection should be considered in SWM with significant vascular encasement of proximal arteries to limit postoperative ischemic complications., (Copyright © 2017 by the Congress of Neurological Surgeons)

Background: There is no objective and readily accessible method for the preoperative determination of atypical characteristics of a meningioma grade., Objective: To evaluate the feasibility of using fractal analysis as an adjunctive tool to conventional radiological techniques in visualizing histopathological features of meningiomas., Methods: A group of 27 patients diagnosed with atypical (WHO grade II) meningioma and a second group of 27 patients with benign (WHO grade I) meningioma were enrolled in the study. Preoperative brain magnetic resonance (MR) studies (T1-wieghted, post-gadolinium) were processed and analyzed to determine the average fractal dimension (FDa) and maximum fractal dimension (FDm) of the contrast-enhancing region of the tumor using box-count method. FDa and FDm as well as particular radiological features were included in the logistic regression model as possible predictors of malignancy., Results: The cohort consisted of 34 women and 20 men, mean age of 62 ± 15 yr. Fractal analysis showed good interobserver reproducibility (Kappa >0.70). Both FDa and FDm were significantly higher in the atypical compared to the benign meningioma group (P < .0001). Multivariate logistic regression model reached statistical significance with P = .0001 and AUC = 0.87. The FDm, which was greater than 1.31 (odds ratio [OR], 12.30; P = .039), and nonskull base localization (OR, .052; P = .015) were confirmed to be statistically significant predictors of the atypical phenotype., Conclusion: Fractal analysis of preoperative MR images appears to be a feasible adjunctive diagnostic tool in identifying meningiomas with potentially aggressive clinical behavior., (Copyright © 2016 by the Congress of Neurological Surgeons)

Background: Magnetic resonance elastography (MRE) analyzes shear wave movement through tissue to determine stiffness. In a prior study, measurements with first-generation brain MRE techniques correlated with intraoperative observations of overall meningioma stiffness., Objective: To evaluate the diagnostic accuracy of a higher-resolution MRE technique to preoperatively detect intratumoral variations compared with surgeon assessment., Methods: Fifteen meningiomas in 14 patients underwent MRE. Tumors with regions of distinctly different stiffness were considered heterogeneous. Intratumoral portions were considered hard if there was a significant area ≥6 kPa. A 5-point scale graded intraoperative consistency. A durometer semiquantitatively measured surgical specimen hardness. Statistics included χ, sensitivity, specificity, positive and negative predicative values, and Spearman rank correlation coefficient., Results: For MRE and surgery, 9 (60%) and 7 (47%) tumors were homogeneous, 6 (40%) and 8 (53%) tumors were heterogeneous, 6 (40%) and 10 (67%) tumors had hard portions, and 14 (93%) and 12 (80%) tumors had soft portions, respectively. MRE sensitivity, specificity, and positive and negative predictive values were as follows: for heterogeneity, 75%, 100%, 100%, and 87%; for hardness, 60%, 100%, 100%, and 56%; and for softness, 100%, 33%, 86%, and 100%. Overall, 10 tumors (67%) matched well with MRE and intraoperative consistency and correlated between intraoperative observations (P = .02) and durometer readings (P = .03). Tumor size ≤3.5 cm or vascular tumors were more likely to be inconsistent (P < .05)., Conclusion: MRE was excellent at ruling in heterogeneity with hard portions but less effective in ruling out heterogeneity and hard portions, particularly in tumors more vascular or <3.5 cm. MRE is the first technology capable of prospectively evaluating intratumoral stiffness and, with further refinement, will likely prove useful in preoperative planning.

Background: Although the combined petrosal approach has significant advantages for medium to large petroclival lesions, it carries the risk of a few major complications. The cerebrospinal fluid leak rate with this approach has been reported to be as high as 15%., Objective: To describe an innovative technique of watertight dural closure with a long microplate-bridge technique for the combined petrosal approach., Methods: We describe our method of watertight dural closures with the microplate-bridge technique for combined petrosal approaches using cadaveric heads and clinical cases. We review our postoperative outcomes in respect to cerebrospinal fluid leaks., Results: The technique involves a fascial graft to the presigmoid-subtemporal defect, fixated with a long microtitanium plate over the cranial base side. The fascial graft is augmented by covering it with an abdominal fat graft and a vascularized pericranial flap. This technique was performed in 23 patients after surgical resection of petroclival meningiomas with only 1 postoperative cerebrospinal fluid leak (4.4%)., Conclusion: We recommend this safe and simple closure technique during skull base surgery.

Meningiomas represent about 20% of intracranial tumors and are the most frequent nonglial primary brain tumors. Diagnosis is based on computed tomography (CT) and magnetic resonance imaging (MRI). Mainstays of therapy are surgery and radiotherapy. Adjuvant chemotherapy is tested in clinical trials of phase II. Patients are followed clinically by imaging. However, classical imaging modalities such as CT and MRI have limitations. Hence, we need supplementary imaging tools. Molecular imaging modalities, especially positron emission tomography (PET), represent promising new instruments that are able to characterize specific metabolic features. So far, these modalities have only been part of limited study protocols, and their impact on clinical routine management is still under investigation. It may be expected that their extended use will provide new aspects about meningioma imaging and biology. In the present article, we summarize PET imaging for meningiomas based on a thorough review of the literature. We discuss and illustrate the potential role of PET imaging in the clinical management of meningiomas. Finally, we indicate current limitations and outline directions for future research.

Background: Anterolateral meningiomas of the foramen magnum (FMMs) represent a neurosurgical challenge because they grow in close contact with osteoarticular, nervous, and vascular structures that cannot be sacrificed or retracted., Objective: To evaluate our strategy and results in 26 patients with FMMs and analyze factors affecting the decision-making process, resection, and outcome., Methods: Among 26 consecutive symptomatic FMM (10 anterior, 16 lateral) patients (16 women, 10 men, ages 28-82 years), 4 older than 70 years of age were untreated. Twenty-two were operated on using a posterolateral approach, with the vertebral artery transposed in 19 and the occipital condyle drilled in 10. We analyzed the characteristics and outcome of untreated cases, the utility of THE occipital condyle drilled, the difficulties of microdissection, morbidity and total removal rates, the outcome of tumor residues, and the literature on radiosurgery., Results: Three of 4 untreated patients remained clinically stable at 2 to 5 years. After systematic vertebral artery medial transposition and occipital condyle drilled in 6 cases, our technique evolved with experience in the next 16 (vertebral artery transposed in 13 of 16; occipital condyle drilled in 4 of 13) for dissecting anteriorly beyond midline (anterior FMMs). Retrocondylar access was sufficient for lateral FMMs. Tumors were totally removed in 16 of 22 (73%). One patient died, and 4 had permanent deficits. Follow-up of more than 5 years in 12 patients showed no C0-1 instability, and slight increase of tumor residue size 7 years after surgery. In the literature, 15 FMMs treated with radiosurgery are reported, 13 at diagnosis and 2 at recurrence, with short-term clinical and radiological safety and efficacy., Conclusion: We currently recommend (1) aiming for subtotal removal in difficult cases, (2) remaining conservative in asymptomatic or elderly patients with mild symptoms, and (3) considering radiosurgery at diagnosis for small (<30 mm) symptomatic FMMs or as an adjunct for evolving residues/recurrences in poor candidates for resection.

Objective: Meningiomas arising from the falcotentorial junction are relatively rare, and the description of the surgical nuances in approaching these tumors is limited. We describe our surgical management of these lesions in detail., Methods: From 2001 to 2005, 9 patients underwent operation for meningiomas arising from the falcotentorial junction, with some extending to and/or invading the torcula. All patients were assessed preoperatively with magnetic resonance neuroimaging and cerebral angiography. Furthermore, preoperative embolization was attempted in all cases. A supratentorial/infratentorial torcular craniotomy technique was used in all but 1 of these cases., Results: The average dimensions of the falcotentorial meningiomas were 5.1 x 4.4 x 4.2 cm. The angiograms revealed that these tumors were fed by branches of the internal carotid artery, choroidal arteries, branches of the meningohypophyseal trunk, and branches of the posterior cerebral artery. Preoperative embolization was achieved in only 2 patients. Five patients had gross total resection (Simpson grade 1), and 4 had subtotal resection (Simpson grade 4). Two of the tumors (22%) recurred during a mean follow-up period of 49 months (range, 17-88 months). The most common complication after surgery was cortical blindness, but all postoperative visual deficits had fully recovered at the last follow-up evaluation within several months., Conclusion: An excellent outcome can be expected with detailed preoperative neuroimaging and knowledge of the nuances of the surgical technique that we describe in detail in this article.

Objective: Idiopathic myelofibrosis is a clonal stem cell disorder that leads to ineffective erythropoiesis accompanied by reactive myelofibrosis (bone marrow fibrosis). As a consequence, extramedullary hematopoiesis characteristically develops. The central nervous system is rarely affected; the spinal canal and the cranial meninges are generally the preferred locations. Extramedullary hematopoiesis within central nervous system primary tumors have already been reported but, to our knowledge, never before in a patient with evidence of idiopathic myelofibrosis., Clinical Presentation: A patient experiencing generalized idiopathic myelofibrosis developed a hemorrhagic intracranial meningioma containing islets of extramedullary myeloid metaplasia., Intervention: The tumor was radically removed through a right frontal craniotomy. After surgery, the patient recovered completely and was discharged with a normal neurological status. After 6 years, the patient is in excellent condition with no sign of recurrence on magnetic resonance imaging scans., Conclusion: The reasons for this uncommon association are uncertain, but we hypothesize that myeloid islets may be involved in the origin of the tumor as well as in its acute hemorrhagic onset. Moreover, we suggest that in the presence of proven idiopathic myelofibrosis intracranial myeloid metaplasia should be ruled out by appropriate neuroimaging and considered as a potential diagnosis in the presence of brain lesions.

Objective: Olfactory groove meningiomas account for 8 to 13% of all intracranial meningiomas. Surgical removal is often performed through the bifrontal, unilateral subfrontal (frontolateral), or pterional approach. We report on the clinical outcome and recurrence rate after surgical treatment of olfactory groove meningiomas in our neurosurgical department., Methods: A retrospective study was conducted by analyzing the charts of the patients, including surgical records, discharge letters, histological records, follow-up records, and imaging studies., Results: A total of 1800 meningiomas were operated on between 1978 and 2002 in our department. There were 82 patients with olfactory groove meningiomas, including 63 women and 19 men with a mean age of 57.8 years (age range, 33-91 yr). Most patients presented with mental disturbance. Tumors were operated through the bifrontal (n = 46), frontolateral (n = 34), and pterional (n = 2) approaches. Total tumor removal (Simpson Grade 1 or 2) was achieved in most cases (91.2% frontolateral, 93.5% bifrontal). Perioperative mortality was 4.9% (four out of 82 patients, all operated through the bifrontal approach). The overall recurrence rate was 4.9%, with four patients requiring surgery. The mean follow-up period was 63.4 months (range, 4-270 mo)., Conclusion: Olfactory groove meningiomas were removed mainly through two different surgical approaches. Even in large tumors, high rates of total tumor resection could also be achieved with low recurrence rates using the simple and minimally invasive frontolateral approach. In recent years, we have preferred to use the frontolateral approach, which provides quick access to the tumor with less brain exposure while still enabling total tumor removal with a low morbidity rate and no mortality.

Objective: We present an unusual dural-based follicular lymphoma with radiological and macroscopic features similar to a meningioma. The unusual location of this tumor and its distinction from meningioma, mucosa-associated lymphoid tissue-type marginal zone B-cell lymphoma of the dura, and intraparenchymal central nervous system lymphoma, dramatically alters the patient's postoperative treatment. The case illustrates the clinical, radiological, and histological relevance of this rare entity., Clinical Presentation: A 41-year-old Caucasian man with chronic bifrontal headaches and a raised area over his left frontal cranium that persisted for 1 year presented to the emergency room with nausea and vomiting. His family reported that the patient demonstrated increased irritability and aggressive behavior. A computed tomographic scan revealed a large mass of the left frontal convexity with edema and mass effect. Magnetic resonance imaging scans showed a 5-cm homogeneously enhancing mass in the left posterior frontal lobe., Intervention: Preoperatively, the patient underwent angiography and embolization of the tumor. The patient underwent gross total resection of tumor. The dural-based tumor invaded the cranium and scalp. Neuropathological findings were consistent with low-grade follicular lymphoma. The patient is currently undergoing radiation and chemotherapy., Conclusion: The current case represents the first report of extensive intracranial dural involvement by a follicular lymphoma that shows a classic immunophenotype by immunohistochemistry and flow cytometry. The case illustrates the clinical and radiographic similarities between dural-based lymphoma and meningioma. Distinguishing dural-based follicular lymphoma from mucosa-associated lymphoid tissue-type lymphoma and from intraparenchymal primary central nervous system lymphomas, which are more often large cell lymphomas with more aggressive biological behavior, is essential for proper clinical management.

Objective: To provide clinical data concerning the visual outcome and recurrence rate of medial sphenoid wing meningiomas in consideration of two different subgroups of this tumor entity., Methods: Among 256 sphenoid wing meningiomas, there were 108 medial sphenoid wing meningiomas of globoid shape. They were classified into Group 1 (without cavernous sinus involvement) and Group 2 (with cavernous sinus involvement). En plaque meningiomas were excluded from the analysis. The charts of the patients including surgical records, discharge letters, follow-up records, and imaging studies were analyzed retrospectively., Results: There were 39 Group 1 tumors and 69 Group 2 tumors. For microsurgical tumor removal, the frontolateral (15.7%) or the pterional approach (84.3%) was performed. Total resection was achieved in 92.3% of patients with Group 1 tumors and 14.5% of those with Group 2 tumors. Radiological recurrence was observed in 7.7% (Group 1 tumors) and 27.5% (Group 2 tumors). The mean follow-up time was 79.04 months (6.59 yr). Improvement of visual function (or stable visual function) was observed in 56% (44%) of patients with Group 1 tumors, in 30% (60%) with newly diagnosed Group 2 tumors, and 10% (70%) undergoing recurrent surgery for Group 2 tumors., Conclusion: Group 1 meningiomas present a more favorable subgroup with fortunate visual outcome. In Group 2 tumors, visual improvement was less favorable and radical removal is limited because of cavernous sinus infiltration, with consequential higher recurrence rates. Patients harboring recurrent Group 2 tumors with deteriorating visual function profit from microsurgery because vision can be preserved on the same preoperative level in the majority.

Objective: Meningiomas arising from the petroclival region remain a challenging surgical problem. Because of the substantial risk of neurological morbidity, uniformly pursuing a gross total resection (GTR) to minimize tumor recurrence rates may not be justified. We sought to define optimal resection goals based on risk factors for postoperative neurological morbidity and tumor recurrence rates., Methods: This series represents our experience with 137 meningiomas arising from the petroclival region resected between June 1993 and October 2002. There were 38 male and 99 female patients with a mean age of 53 years., Results: GTR was achieved in 40% of patients, and near total resection (NTR) was achieved in 40% of patients. One operative death occurred. Twenty-six percent of patients experienced new postoperative cranial nerve deficits, paresis, or ataxia when assessed at a mean follow-up of 8.3 months. The risk of cranial nerve deficits increased with prior resection (P < 0.001), preoperative cranial nerve deficit (P = 0.005), tumor adherence to neurovascular structures (P = 0.046), and fibrous tumor consistency (P = 0.005). The risk of paresis or ataxia increased with prior resection (P = 0.001) and tumor adherence (P = 0.045). Selective NTR rather than GTR in patients with adherent or fibrous tumors significantly reduced the rate of neurological deficits. Radiographic recurrence or progression occurred in 17.6% of patients at a mean follow-up of 29.8 months. Tumor recurrence rates after GTR and NTR did not differ significantly (P = 0.111)., Conclusion: Intraoperatively defined tumor characteristics played a critical role in identifying the subset of patients with an increased risk of postoperative deficits. By selectively pursuing an NTR rather than a GTR, neurological morbidity was reduced significantly without significantly increasing the rate of tumor recurrence.

Objective: Despite apparent gross total resection, olfactory groove meningiomas have a high rate of late recurrence (average, 23%). In this retrospective study, we confirmed that the sites of these recurrences are the cranial base and paranasal sinuses. We postulated that these recurrences stem from conservative handling of the underlying invaded bone. Therefore, we analyzed patient outcomes according to the radicality of surgical resection., Methods: Fifteen consecutive patients with a diagnosis of olfactory groove meningioma were treated surgically between 1992 and 2001 (nine new cases, six recurrent). Only patients with benign meningiomas were included; atypical and malignant meningiomas were excluded. Surgical resection included the dura and drilling of the underlying bone and resection of involved mucosa. We reviewed each patient's clinical records, radiological studies, sites of recurrence, grade of previous resection, and complications., Results: Olfactory groove meningiomas invaded the underlying bone in 13 cases. All patients with recurrence had previously undergone a surgical resection corresponding only to Simpson Grade 2, which does not include the removal of underlying invaded bone. The sites of recurrence were in the cranial base or adjacent paranasal sinuses. The time to recurrence varied from 1 to 12 years (average, 7 yr; mean, 8 yr). Three patients had undergone one previous resection, two had undergone two previous resections, and one had undergone four previous operations. The ethmoid sinus was involved in all cases of recurrence, either with the sphenoid sinus or with an intracranial recurrence. Thirteen patients underwent complete resection of underlying bone and the invaded paranasal sinuses, then reconstruction of the anterior fossa. No patient died. There were three instances of cerebrospinal fluid leakage (one requiring operative repair), one case of delayed worsening vision after initial improvement, and two cases of transient cranial nerve palsy (Cranial Nerves III and IV). There was no recurrence at follow-up (average, 3.7 yr; range, 1-7.3 yr)., Conclusion: The cranial base and paranasal sinuses are sites of predilection for recurrence of olfactory groove meningiomas. Recurrence is the result of a direct extension attributable to incomplete resection of involved bone and regrowth at the edge of a previous surgical field. Extensive resection of all suspicious underlying bone is a complement to radical removal of these lesions. Reconstruction with a vascularized pericranial flap to prevent cerebrospinal fluid leakage is crucial.

Objective and Importance: Surgical sacrifice of the straight sinus may be performed during intracranial tumor resection. Sacrifice of the straight sinus is associated with an unpredictable risk of venous infarction. We describe a patient with a falcine meningioma who underwent endovascular balloon test occlusion of the straight sinus before surgical resection., Clinical Presentation: A 48-year-old woman presented with symptoms resulting from a 4-cm-diameter meningioma in the left occipital region. Along its inferior margin, the tumor abutted the straight sinus. Cerebral angiography demonstrated occlusion of the posterior one-third of the superior sagittal sinus but patency of the straight sinus., Technique: A 4-mm angioplasty balloon was directed into the straight sinus via the right jugular vein. In addition to clinical assessments, the pressure within the proximal straight sinus, upstream from the balloon, was measured before and during inflation. Severe headaches followed balloon inflation, and the pressure in the proximal straight sinus increased 18 mm Hg. With balloon deflation, the clinical and hemodynamic findings immediately returned to normal. On the basis of these findings, the straight sinus was preserved during surgery., Conclusion: This technique is straightforward and allows some assessment of the physiological responses and individual tolerance to sinus occlusion before surgery.

Objective: The preoperative localization of superficial intracranial lesions is often necessary for accurate burr hole placement or craniotomy siting. It is not always easy, however, to localize the lesions over the scalp working only from computed tomographic images. We developed a simple method for such localization using a laser pointer during the preoperative computed tomographic examination., Methods: The angle of incidence, extending from a point on the scalp to the center of the computed tomographic image, is measured by the software included with the scanner. In the gantry, at the same angle as on the image, a laser is beamed from a handmade projector onto the patient's scalp toward the center of the gantry. The point illuminated on the patient's head corresponds to that on the image. The device and the method are described in detail herein., Results: We applied this technique to mark the area for the craniotomy before surgery in five patients with superficial brain tumors. At the time of surgery, it was confirmed that the tumors were circumscribed precisely., Conclusion: The technique is easy to perform and useful in the preoperative planning for a craniotomy. In addition, the device is easily constructed and inexpensive.

Objective: The statement that intracranial meningiomas are cleavable tumors has to be seriously questioned from a surgical standpoint. The purpose of this study was 1) to analyze the operative reports of a personal series of meningiomas to evaluate the percentages of the tumors that could be dissected by passing in the extrapial plane (i.e., "cleavable") and of those in which the dissection had to be subpial (i.e., "noncleavable") and 2) to see whether preoperative angiography could help in predicting cleavability., Methods: The series includes 150 consecutive patients with intracranial meningiomas diagnosed with computed tomographic scans and explored preoperatively by selective external/internal carotid angiography, operated on using microsurgical techniques, and followed for more than 4 years., Results: Dissection between tumor and underlying cortex could be achieved in the extrapial plane predominantly (i.e., on more than two-thirds of the interface) in only 54.6% of patients. On angiography, the pial-cortical arterial supply participated in at least equal part with the meningeal-dural arterial supply in vascularization of the tumor in 59.4% of patients. In this group, dissection could pass through the extrapial plane in only 34.8% of patients. Conversely, when meningeal-dural arterial supply was predominant on angiography, which occurred in 40.6% of patients, dissection could be achieved in the extrapial plane in 83.6% of patients. This difference is statistically significant (P < 0.001)., Conclusion: Participation of pia mater in the vascular supply of intracranial meningiomas, and consequently, difficulty of dissection, can be predicted preoperatively on angiography. Knowledge of the arterial supply of the tumor before surgery is an important aid to the surgeon in preparing for and performing the operation.

Objective: Radiosurgery is increasingly being used to treat cranial base tumors. Since 1989, 55 patients with cranial base meningiomas were treated at Stanford University Medical Center with linear accelerator radiosurgery. An analysis of the clinical and radiographic results of this patient population was the focus of this study., Methods: The mean patient age was 55.1 years (range, 28-82 yr). The mean tumor volume was 7.33 cm3 (range, 0.45-27.65 cm3). The radiation dose averaged 18.3 Gy (range, 12-25 Gy), delivered with an average of 2.2 isocenters (range, 1-5). Patients were evaluated retrospectively through clinic notes from follow-up examinations, and residual tumor volume was measured during follow-up imaging studies. The length of follow-up averaged 48.4 months (range, 17-81 mo)., Results: Tumor stabilization after radiosurgery was noted in 38 patients (69%), shrinkage in 16 patients (29%), and enlargement in only 1 patient (2%). The results of follow-up magnetic resonance imaging demonstrated decreased central contrast uptake in 11 meningiomas (20%), possibly indicating evidence of central tumor necrosis or tumor vessel obliteration. Neurological status was improved in 15 patients in the series (27%) and unchanged in 34 patients (62%). Three patients (5%) died during the follow-up period, all as a result of causes other than tumor progression. Three patients (5%) developed new permanent symptoms (one patient with seizures, one patient with mild right hemiparesis, and one patient with both vagal and hypoglossal nerve palsy). All other complications were transient, including partial trigeminal nerve palsy in seven patients and diplopia in three patients. The 2-year actuarial tumor control rate was 98%., Conclusions: Although our follow-up period is short, this experience corroborates previous reports that radiosurgery can be used to ablate selected small cranial base meningiomas, with good clinical results and modest morbidity.

Objective: We report a group of eight patients with a distinctive histological variant of meningioma that is associated with severe peritumoral edema. The clinical presentation, radiographic findings, and histology of this type of tumor may lead to misdiagnosis as an aggressive or malignant process., Methods: We reviewed the histology from patients who had removal of meningiomas performed in our institution between 1978 and 1992. Tumors having abnormal proliferation of cells in the intramural vascular spaces were selected for study; case histories and radiographs were reviewed. Tumor material was subjected to special stains, immunocytochemical examination, and election microscopy., Results: Several lesions were misread radiographically as being malignant. Patients underwent craniotomy with complete excision of the tumor. All lesions were small (< or = 3 cm), and no brain invasion, unusual tumor vascularity, or dural sinus involvement was noted in any case. Histologically, the meningioma pattern in each case was meningothelial and benign in appearance. The immunocytochemical and electron microscopic features of the unusual cells in the blood vessel walls are most consistent with their being of pericytic origin. All patients have remained asymptomatic and without evidence of tumor recurrence with follow-up from 3 to 12 years., Conclusion: These tumors showed proliferation of pericytes in blood vessel walls and represent a new subtype of meningothelial meningioma. The apparently benign nature of these lesions necessitates their recognition. Characteristic findings of pericytic proliferation associated with edema generation have led us to descriptively term this the PEG variant of meningioma.

We examined the proliferative potentials of meningiomas in 120 patients using the MIB-1 antibody against the Ki-67 antigen and compared them with the clinicoradiological features. The Ki-67 staining index (SI) did not relate to the age and sex of the patients or the location of the tumors. Asymptomatic meningiomas showed significantly lower SIs (mean +/- standard deviation [SD], 0.87 +/- 0.56%) than symptomatic meningiomas (mean +/- SD, 1.63 +/- 2.17%). We found no relation between SIs and clinical symptoms and signs in the symptomatic meningiomas. A weak correlation was found between the size of tumors and Ki-67 SIs (r = 0.21; P = 0.024). There were significant differences in SIs between calcified (mean +/- SD, 0.77 +/- 0.41%) and noncalcified tumor (mean +/- SD, 1.75 +/- 2.25%). Diffusely calcified tumors (mean +/- SD, 0.57 +/- 0.34%) showed lower SIs than focally calcified tumors (mean +/- SD, 0.92 +/- 0.41%). Lobulated tumors showed higher SIs (mean +/- SD, 2.85 +/- 3.68%) than round tumors (mean +/- SD, 1.06 +/- 0.67%). Tumors with perifocal edema or unclear borders had higher SIs than did those without such features. Signal intensities on T1-weighted magnetic resonance images had no relation to SIs, whereas low-intensity tumors on T2-weighted images, most of which presented diffuse calcification on computed tomographic scans, showed lower SIs. This study indicates that several clinicoradiological features relate to the proliferative potential of meningiomas and that they may contribute to the management of patients.

Although generally benign tumors, meningiomas may be associated with extensive peritumoral brain edema as seen on computed tomographic scans. Fifty-two patients with intracranial meningiomas were studied, and the hypodense areas on computed tomographic scans were related to the intraoperative microsurgical findings and to the sizes of the tumors. We have identified three kinds of tumor-brain interfaces characterized by different difficulties in microsurgical dissection: smooth type, transitional type, and invasive type. These different microsurgical interfaces seem to correlate very precisely with computed tomographic images of halo-like and finger-like hypodense areas, allowing prediction of the microsurgical effort to be made in the surgery of meningiomas. The size of the tumor seems to be important in our subjects in determining the amount of edema produced. Indeed, a positive correlation (P < 0.001) was found between the sizes of the tumors and the extent of peritumoral hypodensity. A positive correlation (P < 0.002) also has been found between grade of edema and cortical penetration. Cerebral cortex disruption was systematically observed by us in invasive-type meningiomas and in 3 of 21 cases (14.3%) in transitional-type meningiomas. No penetration was observed in smooth-type meningiomas.

To evaluate the response of cavernous sinus meningiomas to stereotactic radiosurgery, we reviewed our 54-month experience with 34 patients. All patients underwent radiosurgery with a 201-source cobalt-60 gamma unit. Twenty-eight patients (82%) had previous histological confirmation of a meningioma (1 to 5 cranial base craniotomies per patient); 6 (18%) were treated on the basis of neuroimaging criteria alone. The single-fraction radiation tumor margin dose (10 to 20 Gy) was designed to conform to the irregular tumor volumes in all patients. The maximum radiation dose to the optic nerve or tract was reduced to 9 Gy in 31 patients. No patient had tumor growth (100% tumor control) during the follow-up interval (median, 26 mo). Tumor regression was observed in 56% of patients imaged at an average of 18 months. Eight patients (24%) improved clinically at follow-up examinations. Four patients developed new or worsened cranial nerve deficits during the follow-up interval; two had subsequent full improvement. No patient developed an endocrinopathy or new extraocular muscle paresis. Stereotactic radiosurgery, using multiple isocenter dosimetry facilitated by the gamma unit, is an accurate, safe, and effective technique to prevent the growth of tumors involving the cavernous sinus. Despite the proximity of such tumors to adjacent cranial nerves, complications were rare. The maximum length of hospital stay was 36 hours, and all patients returned to their preoperative employment status within 3 to 5 days.(ABSTRACT TRUNCATED AT 250 WORDS)

We studied a patient with a falx meningioma in the right supplementary motor area and a left-sided hemiparkinsonism that resolved after the tumor was removed. Because there was no evidence of distortion of the basal ganglia and midbrain by the tumor on neuroradiological examination, the possible mechanism of parkinsonism is an impairment of the basal ganglia output to the supplementary motor area. Positron emission tomography scans with 2-[18F]fluoro-2-doxy-D-glucose and 6-L-[18F]fluorodopa were performed to measure regional cerebral glucose metabolism and striatal dopamine metabolism, respectively. Regional cerebral glucose metabolism was decreased in the striatum of the side of the lesion, although dopamine metabolism was normal. These data suggest that the tumor may have impaired synaptic function of the striatum as a whole, giving rise to contralateral hemiparkinsonism without an impairment of the presynaptic dopaminergic nerve terminals in the striatum.

Malignancy is rare in intracranial meningiomas. Although the topic is widely discussed, there is little agreement in the literature as to the histological and radiological features that warrant the diagnosis of malignant meningioma. Three patients are described who had soft-tissue masses and underlying osteolytic lesions on computed tomography. All three patients also had a large intracranial component that proved to be a malignant meningioma. Rarely do meningiomas have all three of these features. We propose that a meningioma causing osteolysis and soft-tissue extension should be considered malignant until proven otherwise.

Seven patients with clinically nonsecreting pituitary adenoma and 5 patients with meningioma were examined with positron emission tomography using [11C]-LL-deprenyl and [11C]-LL-methionine. The dynamics of the uptake of [11C]-L-deprenyl in the pituitary adenomas demonstrated a rapid and high uptake immediately after the injection, and, later, an almost constant level was observed that was equal to or higher than that observed in normal brain tissue. In the meningiomas, however, the initially high uptake was followed by a marked decrease with time, reaching a level that was approximately half that observed in brain tissue. The study demonstrated high binding of [11C]-L-deprenyl to monoamine oxidase B in pituitary adenomas, whereas the binding in meningiomas was very low. This fact can be used in the differential diagnosis of pituitary adenoma and parasellar meningioma. Operative samples from 10 patients with meningioma and from 5 patients with pituitary adenoma were analyzed biochemically for activity of monoamine oxidase B, using [14C]-phenyl-ethylamine as substrate. The nonsecreting pituitary adenomas demonstrated high enzyme activity, the secreting adenomas about one-tenth of that of the nonsecreting, and the meningiomas one-thirtieth of that of nonsecreting adenomas.

Two patients with verified meningiomas involving the posterior part of the falx and the midline tentorium extending into the pineal region are reported. Preoperative angiography disclosed occlusion of the straight sinus in both patients. The operative results are described, and the safety of surgical occlusion of the galenic system is discussed.

The rare combination of spinal and intracranial meningeal hemangiopericytomas in the same patient is reported. The coexistence of cerebral and spinal meningiomas of all histological subtypes is distinctly uncommon with only nine cases found in the literature.

Thirteen patients with intracranial meningiomas of the skull base were treated with one or more high-activity iodine-125 seeds. In 11 patients, the seeds were implanted stereotactically under local anesthesia. A minimum dose of 100 to 500 Gy was delivered to the tumor at a dose rate of 5 to 25 cGy/h. Indications for this procedure included recurrence after initial surgery or as the primary modality of treatment in patients who were not candidates for surgery. All 13 patients are alive at a median follow-up of 15 months. Nine of 11 patients (82%) without calcification in their meningiomas achieved complete response. The remaining 4 patients-2 with calcification and 2 without--achieved partial response. No early or late complications were observed. We conclude from our experience that both recurrent and primary meningiomas of the skull base can be treated effectively with permanent iodine-125 brachytherapy.

Radiation-induced meningiomas are becoming increasingly well-recognized. We report a case of a 35-year-old man who developed a suprasellar meningioma 9 years after receiving a radiation dose of 4480 cGy for a pituitary adenoma. The literature is also reviewed.

This study presents 20 cases of meningioma of various intracranial locations, all of which were removed with the carbon dioxide surgical laser system. The carbon dioxide laser is contrasted with other means of meningioma removal to emphasize the advantages of this new technology. These advantages include: (a) the ability to operate with smaller exposures, (b)reduced brain retraction, (c) a reduced amount of mechanical manipulation by vaporizing the tumor mass, (d) vaporization of the dural attachment after the removal of tumor, (e) improved operative precision, and (f) decreased intraoperative significant advancement in the ability to remove meningiomas that might prove difficult to extirpate by conventional means.

A rare case of meningioma located in the 4th ventricle is reported. The mass was successfully removed. The authors also review 14 reported cases of this type of tumor.

We are reporting a case of a ventrally placed intradural meningioma at the C-7, T-1 level that was shown clearly on a computed tomographic scan without the use of metrizamide. This greatly facilitated the planning of our posterolateral approach, which permitted a complete removal of the tumor with minimal manipulation of the spinal cord.