Surgical Strategy in Modification of the Transpetrosal Approach to Avoid Postoperative Venous Complications: A Report of 74 Consecutive Cases.

BACKGROUND: The transpetrosal approach is a complex skull base procedure with a high risk of complications, particularly caused by injury of the venous system. It is in part related to variability of blood outflow pathways and their distinctive patterns in each individual patient. OBJECTIVE: To evaluate outcomes and complications after skull base surgery with use of the petrosal approach modifications, which selection was based on the detailed preoperative assessment of venous drainage patterns. METHODS: Overall, 74 patients, who underwent surgery via the transpetrosal approach at our institution between 2000 and 2017, were included in this study. In all cases, the venous drainage pattern was assessed preoperatively and categorized according to the predominant blood outflow pathway into four types as previously suggested by Hacker: (1) sphenoparietal sinus (SpPrt), (2) sphenobasal vein (SpB), (3) sphenopetrosal sinus (SpPS), and (4) cortical. The blood outflow through the bridging petrosal vein and the vein of Labbé was also taken into consideration. In patients with SpPrt- and a cortical-type venous drainage, the transpetrosal approach was used in a standard way. In patients with SpB-type venous drainage, limited extradural anterior petrosectomy was combined with intradural anterior petrosectomy after dural opening, superior petrosal sinus transection, tentorial cutting, Meckel's cave opening, and trigeminal nerve mobilization. In patients with SpPS-type venous drainage, after standard petrosectomy, dural opening, and tentorial cutting, SpPS ligation was done followed by 2-week interval before staged definitive tumor resection. RESULTS: Gross total, near-total, and subtotal resection of the lesion (meningioma, 48 cases; retrochiasmatic craniopharyngioma, 11 cases; brain stem cavernoma, 7 cases; other tumors, 8 cases) was achieved in 30 (40.5%), 24 (32.4%), and 20 (27.0%) patients, respectively. Postoperative complications that were possibly related to venous compromise were noted in 18 patients (24.3%), but neither one was major. Of these 18 patients, 9 were symptomatic, but all symptoms-aphasia (4 cases), seizures (2 cases), and confusion (3 cases)-fully resolved after conservative treatment. Overall, 13 patients, including 4 symptomatic, had signal changes on T2-weighted brain MRI, which were permanent only in 3 cases (all asymptomatic). CONCLUSION: Our suggested surgical strategy can be applied to any type of the venous drainage pattern. Preoperative evaluation and intraoperative preservation of the blood outflow pathways are crucial means for safe and effective application of the transpetrosal approach.

Meningioma assessment: Kinetic parameters in dynamic contrast-enhanced MRI appear independent from microvascular anatomy and VEGF expression.

BACKGROUND AND PURPOSE: Kinetic parameters of T1-weighted dynamic contrast-enhanced magnetic resonance imaging (DCE-MRI) are considered to be influenced by microvessel environment. This study was performed to explore the extent of this association for meningiomas. MATERIALS AND METHODS: DCE-MRI kinetic parameters (contrast agent transfer constants Ktrans and kep, volume fractions vp and ve) were determined in pre-operative 3T MRI of meningioma patients for later biopsy sites (19 patients; 15 WHO Io, no previous radiation, and 4 WHO IIIo pre-radiated recurrent tumors). Sixty-three navigated biopsies were consecutively retrieved. Biopsies were immunohistochemically investigated with endothelial marker CD34 and VEGF antibodies, stratified in a total of 4383 analysis units and computationally assessed for VEGF expression and vascular parameters (vessel density, vessel quantity, vascular fraction within tissue [vascular area ratio], vessel wall thickness). Derivability of kinetic parameters from VEGF expression or microvascularization was determined by mixed linear regression analysis. Tissue kinetic and microvascular parameters were tested for their capacity to identify the radiation status in a subanalysis. RESULTS: Kinetic parameters were neither significantly related to the corresponding microvascular parameters nor to tissue VEGF expression. There was no significant association between microvessel density and its presumed correlate vp (P=0.07). The subgroup analysis of high-grade radiated meningiomas showed a significantly reduced microvascular density (AUC 0.91; P<0.0001) and smaller total vascular fraction (AUC 0.73; P=0.01). CONCLUSIONS: In meningioma, DCE-MRI kinetic parameters neither allow for a reliable prediction of tumor microvascularization, nor for a prediction of VEGF expression. Kinetic parameters seem to be determined from different independent factors.

[COMPARATIVE ESTIMATION OF THE SURGICAL TREATMENT RESULTS IN CYSTIC MENINGIOMAS OF THE BRAIN, USING THE STANDARD METHODS AND NEW TECHNOLOGIES].

The results of surgical treatment of 54 patients, suffering the brain cystic meningiomas of various localization, were analyzed. The patients were operated on in universal conditions by neurosurgeons of one operative team, of them 24 ­ using new technologies. Wide application of new technologies in surgery of the brain cystic meningiomas have permitted to reduce the surgical intervention invasiveness essentially, and, as a consequence, to reduce trustworthily the operation time essentially, as well as the intraoperative blood loss severity.

Comparative efficacy of Glubran and polyvinyl-alcohol particles in the embolization of meningiomas.

PURPOSE: Preoperative embolization of meningiomas decreases intraoperative bleeding and shortens operation time. However, in meningiomas predominantly vascularized by the internal carotid artery (ICA) or vertebral artery (VA) branches, embolization of external carotid artery feeder branches may lead to a hemodynamic increase in blood supply from the ICA or VA, whereas embolization of ICA or VA feeder branches with particle embolic agents may be associated with complications. This study investigated the safety and efficacy of Glubran, a liquid embolic agent, for the embolization of this type of meningioma compared with polyvinyl-alcohol (PVA) particles. MATERIALS AND METHODS: From January 2006 to June 2015, 157 consecutive patients (98 females; mean age = 48.3 years) who suffered from meningiomas and were preoperatively referred for embolization were retrospectively analyzed. Glubran (n = 40) and PVA (n = 55) were used to devascularize tumors. Sixty-two patients were not embolized because of dangerous anastomosis or other tumor characteristics. Intraoperative blood loss, intraoperative time, degree of angiographic devascularization and embolization-related complications were analyzed. RESULTS: The intraoperative blood loss and operative time were significantly lower in the Glubran-embolized versus non-embolized group. Furthermore, Glubran embolization significantly reduced intraoperative blood loss and operative time for meningiomas that received their primary blood supply from the ICA and/or VA compared with PVA embolization. CONCLUSIONS: Preoperative meningioma embolization with Glubran decreases intraoperative blood loss and operative time. Furthermore, embolization with Glubran produces more effective devascularization compared with PVA for meningiomas supplied by the ICA and/or VA. Thus, Glubran may represent a better embolic agent for this meningioma subtype.

Role of intratumoral flow void signs in the differential diagnosis of intracranial solitary fibrous tumors and meningiomas.

BACKGROUND AND OBJECTIVE: An absence of signal on magnetic resonance (MR) images caused by blood or cerebral spinal fluid flow is known as a flow void, and may be related to intracranial tumors such as intracranial solitary fibrous tumor (SFT) or meningioma. However, the differential diagnosis of these neoplasms based on flow void configuration is controversial. This study investigated common intratumoral flow void patterns for differentiating intracranial SFT from meningioma. METHODS: From May 2008 to May 2015, 14 patients (10 men, 4 women; 14-63y) received a pathologic diagnosis of primary intracranial SFT, and in 85 patients (23 men, 62 women; 20-76y) a pathologic diagnosis of meningioma was made. Intratumoral flow void signs were retrospectively observed on MR images of all these patients and classified by radiologists blinded to the pathology findings. Statistical significance was established by chi-squared tests. RESULTS: In intracranial SFT patients, the sunburst flow void was detected in 1 case (7.1%) and the serpentine in 13 cases (92.9%). In meningioma patients, the sunburst flow void was detected in 82 cases (96.5%) and the serpentine in 3 cases (3.5%). The differences in the prevalence of the flow void types between the 2 groups were significant (χ(2)=64.348; P<0.01). CONCLUSION: Intracranial SFTs on MR images were more likely to show a serpentine than a sunburst flow void, while the sunburst pattern was far more typical of meningioma. Thus, the pattern of the intratumoral flow void sign may be a useful tool to assist in differentiating these tumors.

The Possible Role of Mast Cells and VEGF in Peritumoural Oedema of Secretory Meningioma.

Objective: Secretory meningiomas constitute a relatively rare subtype of meningiomas and present often with massive peritumoural oedema. From our previous report, a high number of mast cells were demonstrable in this subtype of meningiomas. The present study aimed to obtain more information about mast cell derived progangiogenic factors and mediators as well as VEGF receptors in secretory meningioma. Additionally, the correlation of histological factors such as the presence of mast cells and the radiological evidence of surrounding tumour oedema was analysed. Material and Method: Sixteen cases of secretory meningioma were examined. Relevant clinical information was obtained from the patient files. The peritumoural oedema was determined either by CT or MRI scans and graded as mild, moderate and severe. Immunohistochemical studies of histamine, substance P, serotonin, VEGF and VEGF receptors were performed. A double-blind quantitative evaluation of mast cells staining positively for VEGF in a comparison with total mast cells in secretory meningiomas was made by two histopathologists. Results: There was no immunoreactivity against histamine or substance P within the tumour tissue or in mast cells. Fine granules of serotonin were demonstrated within the mast cells and a coarse granular expression of VEGF was found within the mast cells. Our preliminary data demonstrated that tumours with moderate to severe degree of peritumoural oedema usually contained more than 50% of VEGF-staining positive mast cells. Conclusion: Secretory meningiomas are characterized by a significantly increased number of mast cells. VEGF and serotonin might be involved in the pathophysiological process of this vasogenic brain oedema. The preliminary data demonstrated the potential relation between the radiological evidence of increasing oedema and the high numbers of mast cell staining positively for VEGF.

Correlations of magnetic resonance, perfusion-weighed imaging parameters and microvessel density in meningioma.

PURPOSE: To investigate the correlations of magnetic resonance, perfusion-weighed imaging (PWI) parameters and microvessel density (MVD) in meningioma. METHODS: 48 patients with pathologically confirmed meningioma (grade I, 38 cases; grade II+III, 10 cases) completed preoperative routine magnetic resonance imaging (MRI) and PWI. The cerebral blood volume (CBV) map of solid tumor region and the mean of maximum relative cerebral blood volume (rCBV) were then calculated. Immunohistochemical staining was performed in all specimens to measure the MVD. RESULTS: On the CBV map, benign meningiomas showed a high perfusion signal, while malignant meningiomas exhibited a slightly higher one. The rCBV of benign meningiomas was 9.61±4.76, which was significantly higher than 3.61±0.25 of malignant meningiomas (t=7.165, p=0.000). The MVD of benign meningioma strips was 21.16 ± 11.32, which was also significantly higher than 10.71 ± 5.53 strips of malignant meningiomas (t=2.325, p=0.026). The correlation analysis showed that the mean of maximum rCBV and MVD of meningiomas had significant positive correlations (r=0.718, p=0.000). CONCLUSIONS: The CBV map of benign meningiomas is different to that of malignant meningiomas, and the mean of maximum rCBV and MVD have significant positive correlations.

Pseudo-continuous arterial spin labeling reflects vascular density and differentiates angiomatous meningiomas from non-angiomatous meningiomas.

Pseudo-continuous arterial spin labeling (PCASL) can measure tumor blood flow (TBF) reliably. We investigated meningioma TBF using PCASL and assessed for any correlation with histopathological microvascular density (MVD) and the World Health Organization (WHO) classification. Conventional MRI with contrast T1-weighted images and PCASL were acquired with a 3 T scanner before surgery in 25 consecutive patients with meningiomas. Using the PCASL perfusion map, the mean and maximum TBF were calculated from regions of interest placed in the largest cross-sectional plane of each tumor. Tissue sections from 16 patients were stained with CD31 to evaluate MVD and were assigned a WHO classification. The TBFs were statistically compared with MVD and the histopathological meningioma subtypes. There were 16 meningothelial meningiomas, four angiomatous meningiomas, two fibrous meningiomas, one transitional meningioma, and two atypical meningiomas. We observed significant correlation between MVD and both mean and maximum TBF (p < 0.05). The mean and maximum TBF ((mean)TBF, (max)TBF) in angiomatous meningiomas are significantly higher than that in non-angiomatous meningiomas (p < 0.05). PCASL is useful in assessing meningioma vascularity, and in differentiating angiomatous meningiomas from non-angiomatous meningiomas.

p-CREB expression in human meningiomas: correlation with angiogenesis and recurrence risk.

Despite total surgical resection, a percentage of meningiomas do unexpectedly recur. At present the prediction of recurrence risk and the management of recurrent tumours represent major issues in the patients affected by meningiomas. The present study aims at investigating the prognostic value of the expression of the phosphorylated transcription factor cyclic AMP responsive element binding protein (p-CREB) in a series of meningiomas of different histotype and grade. While no p-CREB expression was found in specimens of normal leptomeninges, 71 % of meningiomas in our cohort expressed p-CREB. In addition, nuclear expression of p-CREB was present in the endothelia of tumor vessels in all of the meningiomas, but not in the vessels of the non-neoplastic meninges. High expression of p-CREB was significantly more frequent in meningiomas showing atypical, chordoid or microcystic histotype (P = 0.0003), high histological grade (P < 0.0001), high Ki-67 labeling index (P = 0.0001), high microvessel density counts (P < 0.0001) and high vascular endothelial growth factor expression (P = 0.0113). In addition, high p-CREB expression was significantly associated with the development of recurrences (P = 0.0031) and it was a significant negative, albeit not independent, prognostic factor for disease free survival in patients with meningiomas submitted to complete surgical removal (P = 0.0019). In conclusion, we showed that p-CREB is expressed in human meningiomas and that it represents a significant predictor of recurrence risk in these tumors. Due to its high expression in more aggressive tumors and in the tumor vessels, it may represent a novel therapeutic target in meningiomas.

Time-Resolved Magnetic Resonance Angiography in the Evaluation of Intracranial Vascular Lesions and Tumors: A Pictorial Essay of Our Experience.

Time-resolved magnetic resonance angiography (TR MRA) is a promising less invasive technique for the diagnosis of intracranial vascular lesions and hypervascular tumors. Similar to 4-dimensional computed tomographic angiography obtaining high frame rate images, TR MRA utilizes acceleration techniques to acquire sequential arterial and venous phase images for identifying, localizing, and classifying vascular lesions. Because of the good agreement with digital subtraction angiography for grading brain arteriovenous malformations with the Spetzler-Martin classification and the good sensitivity for visualizing arteriovenous fistulas, studies have suggested that TR MRA could serve as a screening or routine follow-up tool for diagnosing intracranial vascular disorders. In this pictorial essay, we report on the use of TR MRA at 3.0 T to diagnose intracranial vascular lesions and hypervascular tumors, employing DSA as the reference technique.

Staged 'intentional' bridging vein ligation: a safe strategy in gaining wide access to skull base tumors.

BACKGROUND: The venous drainage of the temporal lobe, through bridging veins to the middle cranial fossa, is pivotal in determining the surgical corridor for skull base lesions. In dealing with select cases, where venous drainage was an obstacle in the surgical approach, we hypothesized that staged 'intentional' ligation of the dominant pathway of venous drainage would provide a safer and wider access to skull base tumors. We study the indications and safety of this surgical strategy in the management of skull base lesions. MATERIALS AND METHODS: From 1995 to 2012, 318 patients with skull base tumors were treated at our institute by the fronto-orbito-zygomatic (FOZ) or transpetrosal approaches, eight of whom we planned for staged 'intentional' bridging vein ligation. Seven patients underwent planned ligation of the bridging veins from the temporal lobe to the middle cranial fossa floor in the first stage, followed by definitive surgery through the desired skull base approach, in the second stage, while in one patient the strategy was abandoned. These patients were evaluated with respect to their clinical presentation, pre- and post-operative radiology including venogram, intra-operative findings and post-operative course. RESULTS: Seven patients, four males and three females, with ages ranging from 16 to 63 years, underwent staged 'intentional' bridging vein ligation. The diagnoses were recurrent craniopharyngioma in four, and petroclival meningioma, sphenopetroclival meningioma and spheno-orbital meningioma in one each. Six of these lesions were approached from the dominant (left) side, while one lesion was on the right side. Venograms done after the first-stage procedure showed obliteration of the dominant venous drainage with opening up of anastomotic venous channels in all patients. All patients tolerated the first-stage procedure well; only one patient showed asymptomatic mild temporal lobe edema on MRI, which resolved in 3 weeks. None of the patients had venous complications after definitive surgery. One patient with recurrent chordoma, who was planned for staged ligation, did not undergo ligation as, intra-operatively, the draining channel turned out to be a cortical vein, which could be mobilized without ligation. CONCLUSION: In an attempt to detether the temporal lobe, the disconnection of the bridging veins from the temporal lobe to the middle cranial fossa floor in the first stage may lead to re-direction of the venous outflow over time. This may allow skull base surgeons a better surgical corridor and ensure safety of venous structures during the definitive surgery.

[Transient charles bonnet syndrome after excision of a right occipital meningioma: a case report].

Charles Bonnet syndrome is a condition characterized by visual hallucinations. These simple or complex visual hallucinations are more common in elderly individuals with impaired peripheral vision. The current report describes a case of transient Charles Bonnet syndrome appearing after the removal of a meningioma. The patient was a 61-year-old man who already had impaired visual acuity due to diabetic retinopathy. Brain MRI revealed a cystic tumor severely compressing the right occipital lobe. Starting on day 2 postoperatively, the patient was troubled by recurring visual hallucinations involving people, flowers, pictures, and familiar settings(the train and a coffee shop). These continued for 3.5 months. This period roughly coincided with the time for the occipital lobe to recover from the compression caused by the tumor, a fact that was confirmed by several MRI scans. ¹²³I-IMP SPECT performed 1 month after the surgical operation showed an area of hypoperfusion in the right parieto-occipital lobe. Based on the patient's clinical course and MRI findings, the mechanism of onset of visual hallucinations in this patient was put forward. The release of pressure in the brain by tumor removal and subsequent recovery changed the blood flow to the brain. This triggered visual hallucinations in the patient, who was already predisposed to developing Charles Bonnet syndrome because of diabetic retinopathy. This case is interesting since it indicates that central neurological factors, as well as visual deficits, may induce the appearance of visual hallucinations in Charles Bonnet syndrome.

Falcotentorial and velum interpositum meningiomas: two distinct entities of the pineal region.

OBJECTIVE: Among pineal region lesions meningiomas are extremely rare and include falcotentorial and velum interpositum meningiomas. It is very difficult to discriminate between these two lesions and description of the clinical presentation and the surgical technique in approaching these tumors is limited. We respectively analyzed a series of patients harboring pineal region meningiomas with regard to clinical features, neuroimaging studies, and results of surgical treatment. METHODS: Clinical data of 5 women and 1 man with pineal region meningiomas treated between January 1993 and December 2012 were retrospectively reviewed. All patients were assessed preoperatively with MRI and cerebral angiography. The only surgical approach we used was occipital transtentorial route. RESULTS: There were four falcotentorial and two velum interpositum meningiomas. The main presenting symptom was headache, dizziness and gait disturbance. The angiogram revealed that these tumors were fed by tentorial artery, posterior choroidal arteries, and branches of the posterior cerebral artery and in four cases additional evidence of occlusion of the galenic venous system was seen. Two patients had total resection (Simpson Grade I and Grade II) and in four patients small remnants of tumor were left (Simpson Grade III). No death occurred in this series. The most common complication after surgery was homonymous hemianopsia which fully recovered in all patients in the follow-up. CONCLUSION: The falcotentorial and velum interpositum meningiomas can be safely managed with the use of occipital transtentorial approach. Homonymous hemianopsia is the most common although always transient complication of surgery.

Supracerebellar "Flyover" Approach to Dumbbell Falcotentorial Meningioma Encasing the Galenic Venous System.

Falcotentorial meningiomas involve the tentorial apex and straight sinus, posing challenges when encasing the galenic venous system.1 Microneurosurgery is considered the best treatment option for large falcotentorial meningiomas because it provides a definitive cure.2 In contrast, Gamma Knife surgery mainly allows the control of smaller or residual tumors after microsurgical resection.3 Approach selection between interhemispheric supratentorial versa supracerebellar transtentorial is dictated by the displacement of the Galen vein.1,4-8Video 1 describes the critical surgical steps of the supracerebellar "flyover" approach for a Bassiouni type II dumbbell falcotentorial meningiomas encasing the galenic venous system. Preoperative embolization was ruled out due to potential additional morbidity and mortality risks.9,10 A perimedian supracerebellar infratentorial transtentorial approach was performed with the patient in ¾ prone Concorde position. After early devascularization and division of the tentorium, the meningioma was internally debulked while preserving the arachnoid plane. The posterior choroidal arteries, internal cerebral veins, basal veins of Rosenthal, and vein of Galen were carefully dissected, and the tumor was completely resected. The patient was discharged on postoperative day 3 with no deficits. Postoperative magnetic resonance imaging confirmed a Simpson grade 1 resection. Pathology revealed a grade 2 meningioma. The patient remained asymptomatic with no recurrence at a 10-year follow-up. The reported case demonstrates that the most critical factor in the choice of approach to midline dumbbell falcotentorial meningiomas is the relationship of the tumor to the galenic venous system and its tributaries.

A hypoxia-inducible factor (HIF)-3α splicing variant, HIF-3α4 impairs angiogenesis in hypervascular malignant meningiomas with epigenetically silenced HIF-3α4.

Hypoxia inducible factor is a dominant regulator of adaptive cellular responses to hypoxia and controls the expression of a large number of genes regulating angiogenesis as well as metabolism, cell survival, apoptosis, and other cellular functions in an oxygen level-dependent manner. When a neoplasm is able to induce angiogenesis, tumor progression occurs more rapidly because of the nutrients provided by the neovasculature. Meningioma is one of the most hypervascular brain tumors, making anti-angiogenic therapy an attractive novel therapy for these tumors. HIF-3α has been conventionally regarded as a dominant-negative regulator of HIF-1α, and although alternative HIF-3α splicing variants are extensively reported, their specific functions have not yet been determined. In this study, we found that the transcription of HIF-3α4 was silenced by the promoter DNA methylation in meningiomas, and inducible HIF-3α4 impaired angiogenesis, proliferation, and metabolism/oxidation in hypervascular meningiomas. Thus, HIF-3α4 could be a potential molecular target in meningiomas.

Embolized meningiomas: risk of overgrading and neo-angiogenesis.

Pre-operative embolization (POE) of meningiomas may induce histological changes which simulate malignancy, possibly resulting in overgrading. Aims of the present study were to identify clues to distinguish malignancy-related features from POE-related changes and to test for overgrading the grading scheme currently in use, in embolized meningiomas. In addition, we aimed to analyze whether the POE procedure may stimulate neo-angiogenesis in meningiomas. The histological features of a series of embolized meningiomas were evaluated and considered for grading assessment. In the same cases neo-angiogenesis was quantified by the evaluation of microvessel density (MVD) and correlated with the interval between POE and surgery. Necrosis and macronucleoli represented common findings in embolized meningiomas. Nonetheless, in most of the cases, necrosis showed an abrupt line of demarcation from the viable tumour tissue, and macronucleoli were restricted to peri-necrotic areas. Suggesting that these were POE-associated changes, exclusion of necrotic areas with an abrupt line of transition and focal macronucleoli from grading assessment resulted in increased specificity and positive predictive value in the identification of recurring meningiomas. In our cohort, MVD significantly increased with the time between POE and surgery, suggesting that POE procedure may induce neo-angiogenesis in meningiomas. In conclusion, a risk of overgrading there exists in embolized meningiomas, as a consequence of the frequent evidence of necrosis and prominent nucleoli in these tumours. In order to avoid overgrading, we suggest that necrosis showing an abrupt line of demarcation and focal peri-necrotic macronucleoli are not included in grading assessment. Also, caution should be used in the interpretation of MVD as a prognostic factor in embolized meningioma, as it may also result from POE procedure.

Risks of presurgical embolization of feeding arteries in 137 intracranial meningeal tumors.

BACKGROUND: Embolization of extra-axial tumors has shown its effectiveness in reducing perisurgical blood loss. However, the complication rate of this procedure is poorly reported. We aimed to evaluate the rate of procedure-related complications and their risk factors. METHODS: From 1998 to 2011, 193 consecutive patients (141 females, 52 males; mean age = 52.9 years) were referred to our institution for presurgical embolization of an extra-axial tumor (meningiomas: n = 178; solitary fibrous tumors: n = 3; other: n = 12). Of 193 patients, 137 (71 %) underwent 141 embolizations (by microparticles: n = 133; by glue: n = 8). The remaining 56 patients (29 %) were not embolized due to unstable catheterization or dangerous anastomosis. Occurrence of neurological deficit was systematically assessed during and after embolization. The risk factors of procedure-related neurological complications were evaluated. RESULTS: Neither intratumoral hemorrhage nor procedure-related death was reported. Two of the 137 patients (1.5 %) had ischemic events with permanent neurological deficit after microparticles embolization. One patient had cortical blindness and one had hemiparesis. Both complications involved the vertebrobasilar system. The first patient had direct intratumoral anastomosis between the middle and the posterior meningeal arteries (PMA); the second one had reflux in the vertebral artery during particles injection in the PMA. Occurrence of ischemic complication was not related to the size of the microparticles. CONCLUSIONS: Though embolization of meningeal tumors is considered as a safe technique, serious neurological complications may occur. Opening of dangerous anastomosis or uncontrolled reflux caused two neurological complications (1.5 %). The size of the microparticles was not associated with the occurrence of neurological event.

Expression of VEGF and collagen XVIII in meningiomas: correlations with histopathological and MRI characteristics.

BACKGROUND: The objective of this study was to assess the possibility of predicting histological characteristics of meningiomas on the basis of preoperative MRI and the correlation of the expression of vascular endothelial growth factor (VEGF) and collagen XVIII with histological parameters already established as predictive of the course of these tumors. METHODS: Expression of VEGF and collagen XVIII as well as other histological characteristics was examined in meningioma tissues from 20 patients. Preoperative MRI, including dynamic imaging of contrast enhancement, was analyzed. Times to maximum enhancement and maximum intensity increase were noted from dynamic imaging. The relative intensity of the tumor in fluid-attenuated inversion recovery (FLAIR), T2-weighted and contrast enhanced T1-weighted images, as well as volumes of tumor and edema, was calculated. The edema-tumor volume ratio was defined as the edema index (EI). RESULTS: Both VEGF and collagen XVIII were expressed in all meningioma samples. Edema was present in 60 % of cases. The strongest correlation of VEGF expression was to EI. Among histological parameters, microvessel density (MVD) and cellularity correlated moderately with VEGF. Collagen XVIII expression correlated strongly with the maximal intensity increase after contrast agent administration (ρ = 0.71, P = 0.001) as well as with MVD and intensity of the meningioma on FLAIR images. CONCLUSION: Meningiomas with faster and more intense enhancement in dynamic studies, indicative of good tumor blood supply and permeability of vasculature, are associated with high levels of collagen XVIII and VEGF expression. Occurrence of peritumoral edema in meningiomas is strongly correlated with expression of VEGF.

Anatomical variation of superior petrosal vein and its management during surgery for cerebellopontine angle meningiomas.

No systematic study is yet available that focuses on the surgical anatomy of the superior petrosal vein and its significance during surgery for cerebellopontine angle meningiomas. The aim of the present study was to examine the variation of the superior petrosal vein via the retrosigmoid suboccipital approach in relation to the tumor attachment of cerebellopontine angle meningiomas as well as postoperative complications related to venous occlusion. Forty-three patients with cerebellopontine angle meningiomas were analyzed retrospectively. Based on the operative findings, the tumors were classified into four subtypes: the petroclival type, tentorial type, anterior petrous type, and posterior petrous type. According to a previous anatomical report, the superior petrosal veins were divided into three groups: Type I which emptied into the superior petrosal sinus above and lateral to the internal acoustic meatus, Type II which emptied between the lateral limit of the trigeminal nerve at Meckel's cave and the medial limit of the facial nerve at the internal acoustic meatus, and Type III which emptied into the superior petrosal sinus above and medial to Meckel's cave. In both the petroclival and anterior petrous types, the most common vein was Type III which is the ideal vein for a retrosigmoid approach. In contrast, the Type II vein which is at high risk of being sacrificed during a suprameatal approach procedure was most frequent in posterior petrous type, in which the superior petrosal vein was not largely an obstacle. Intraoperative sacrificing of veins was associated with a significantly higher rate of venous-related phenomena, while venous complications occurred even in cases where the superior petrosal vein was absent or compressed by the tumor. The variation in the superior petrosal vein appeared to differ among the tumor attachment subtypes, which could permit a satisfactory surgical exposure without dividing the superior petrosal vein. In cases where the superior petrosal vein was previously occluded, other bridging veins could correspond with implications for the crucial venous drainage system, and should thus be identified and protected whenever possible.

[Embolization of the feeding artery of a meningioma with dangerous vascular anastomosis between the middle meningeal artery and the ophthalmic artery].

Preoperative embolization of intracranial meningioma has been applied to reduce intraoperative blood loss and to facilitate microsurgical removal of a tumor. It is well known that one of the reasons of the neurological risk of embolization is due to dangerous anastomosis between the extracranial and the intracranial arteries. One of the most known and dangerous case of anastomosis is between the middle meningeal artery to the ophthalmic artery. A 48-year-old woman underwent preoperative embolization of a large right middle cranial fossa meningioma. The right external carotid angiogram showed that the tumor was fed by the right middle meningeal artery and there was no branch to the right orbital region. The right internal carotid angiogram showed that the right ophthalmic artery originated from the right internal carotid artery and there was no branch to the tumor. The selective angiogram of the anterior branch of the middle meningeal artery disclosed the anastomosis to the right ophthalmic artery. Following embolization of the anterior branch of the middle meningeal artery, the patient underwent embolization of the main feeding branch of the meningioma. She successfully underwent surgical removal of the tumor without any blood transfusion and was discharged without neurological deficit. In addition, to avoid complication in embolization of the feeding artery of a skull base meningioma, clinicians must be aware of the dangerous anastomosis between the middle meningeal artery and the ophthalmic artery, even if conventional external and internal carotid angiograms do not show any anastomosis.