Peritumoural brain oedema in intracranial meningiomas: Influence of tumour size, location and histology

Summary Peritumoural brain oedema was examined retrospectively in 175 patients with 179 intracranial meningiomas. The influence of tumour size, location and histology were investigated.Tumour volume and localization, and the presence of peritumoural brain oedema (PTBOe) were determined by computed tomography (CT). The oedema-tumour volume ratio was defined as Oedema Index (Oel). All patients underwent microsurgical removal of the tumour. Surgically resected meningiomas were classified histopathologically based on criteria of the new World Health Organization (WHO) classification. A close relationship was found between the tumour size and the incidence of peritumoural oedema: with increasing size of the tumour the incidence of oedema also rises, the oedema index, however decreases. Frontobasal and temporobasal meningiomas showed a significant increase in the oedema incidence and the mean oedema index. If major parts of the surface of meningiomas were adjacent to subarachnoid cisterns only a slight tendency for the development of oedema was observed. WHO-III-meningiomas showed a significantly higher oedema incidence (61.1% vs. 94.4%; p<0.004) and mean oedema index (Oel=2.7 vs. 3.7; p<0.0009) than WHO-I-meningiomas. Brain tissue was affected in 59 cases. 19 meningiomas with infiltration into adjacent brain parenchyma revealed a statistically significant increase in oedema incidence (94.7% vs. 51.7%; p<0.0003) and mean oedema index (Oel=3.9 vs. Oel=2.2; p<0.0001) when compared to tumours without any brain tissue involvement in the histopathological specimens. Tumours with large volume, fronto-temporo-basal location and anaplastic histology were not only associated with the highest incidence of oedema formation but also presented with an overproportionate infiltrative growth. Thus, a disruption of the arachnoid or a true brain infiltration may be an essential factor for the development of a PTBOe.     

Cerebral oedema associated with WHO-I,WHO-II,and WHO-III-meningiomas: Correlation of clinical,computed tomographic,operative and histological findings

Summary Meningiomas were studied in 60 patients retrospectively. Clinical, operative and histological findings were correlated with the occurrence and extension of peritumoural oedema as measured by computerized tomography. A relationship was found between both oedema and seizures and between oedema and tumour location. No relationship between tumour size, arachnoid breaching, WHO-grade or tumour vascularity and oedema was detected. In four patients with severe pre-operative oedema, cerebral signs and symptoms persisted despite uncomplicated tumour removal.The present study shows that peritumoural oedema is not only epileptogenic but that it can also cause irreversible cerebral damage as well. Since this study purports to demonstrate that meningiomas with intact leptomeninges can show severe peritumoural oedema, the blood barrier breakdown theory cannot be considered as the only aetiological factor.     

Role of ischaemia in the genesis of oedema surrounding meningiomas assessed using magnetic resonance imaging and spectroscopy

Oedema surrounding meningiomas is well known, but its pathogenesis remains obscure. Perfusion and metabolism in this peritumoural parenchyma were studied preoperatively in eight patients using magnetic resonance imaging, dynamic perfusion scanning and proton spectroscopy. Relative cerebral blood volumes (CBV) and metabolite ratios were calculated for the tumour and peritumoural brain. All meningiomas showed gadolinium enhancement, high choline (Ch), low creatine (Cr) and low N-acetyl aspartate (NAA) [Ch: (Ch + Cr) 0.67, SD 0.13, NAA: (Ch + Cr) 0.18, SD 0.15]. Lactate was present in four tumours [lactate: (Ch + Cr) 0.32, SD 0.27]. Extremely low gadolinium passage and low CBV were seen in the 2 cm peritumoural region, with elevated lactate [lactate: (Ch + Cr) 0.26, SD 0.18]. Four centimetres from tumour margin the CBV was still reduced (65, SD 20% with less lactate [lactate: (Ch + Cr) 0.12, SD 0.01]. Relative CBV is reduced around meningiomas and is associated with lactate, suggesting that oligaemia and altered metabolism may be part of the pathology in peritumoural oedema. Such changes may be important in determining functional recovery after surgery.     

A study on peritumoural brain oedema around meningiomas by CT and MRI scanning

Summary There is a great variability in the amount of peritumoural brain oedema accompanying meningiomas. In a previous study it was found that the degree of brain oedema in the white matter around meningiomas correlated with disruption of the layers (especially the cerebral cortex), which separate the tumour from the white matter, as well as with the size and histological subtype of the tumour.In the present study comprising 9 meningiomas, the volume of oedema was calculated by integration of the cross-sectional oedematous areas on serial MRI slices. The volume of oedema was zero in 3 cases and ranged from 11 to 176.4 ml in the other 6 cases. The MRI-scans also showed disruption of the cortex in all cases, ranging from slight to severe. T₁ and T₂ measurements were made at the level of maximum extension, using a mixed sequence at a field strength of 1.5 T. From the T₂ values tissue water content in % was calculated using the equations: WC=39.36/(R₂ + 37.2) for cortex, and WC=29.63/(R₂ + 27.8) for white matter. These had been obtained by correlating water content with relaxation rates, measured in vitro on human brain autopsy specimens which were subjected to hydration with distilled water or dehydration by hyperosmolar solutions. Mean water content amounted to 82.53% for normal cortex, 74.72% for normal white matter, and 84.59% for oedematous white matter around the tumour.On the assumption that the spread of contrast agent marks the advancement of the front of oedema produced by the tumour, CT-studies were made before, and at 1 1/2, 3 and 6h after contrast infusion. The increase in diameter of the contrast-stained area on the CT-scan allows calculation of the excess of oedema production per unit tumour volume. Of 6 tumours with oedema (mean peritumoural water content of 91% and mean volume of oedema of 69.2 ml) the production excess at the steady-state was 0.18–1.08 ml/h/cm³ tumour volume, whereas 3 tumours without associated oedema had a production excess of 0.03–0.12 ml/h/cm³. Moreover, penetration of the cortex seems to constitute a separate factor determinig the spread of oedema.     

Cystic meningioma

Summary Meningiomas are usually solid tumours. Cystic changes in meningiomas are rare. These cysts may occur extratumoural, peritumoural or intratumoural. Diagnostic difficulties arise in cases of cystic meningiomas. Nine cases of cystic meningiomas were operated on in the past 6 years at the department of neurosurgery, University of Alexandra. The mean age of patients was 46.2 years. Male to female ratio was 1/2. Less oedema was observed in extratumoural cysts, and more oedema in intratumoural cysts. The fluid contained was dark brown or dirty yellow in intratumoural cysts (type C), xanthochromic in peritumoural cysts surrounded by tumour tissue (Type B), or clear fluid in extratumoural cysts (Type A). Based on these two observations it is proposed that the cyst fluid and peritumoural oedema may represent variable degrees of degeneration or secretion by tumour cells. Pre-operatively diagnostic criteria are presented.     

Proliferation rate of intracranial meningiomas as defined by the monoclonal antibody MIB-1

Paraffin-embedded surgical specimens from 55 meningiomas were immunostained after microwave processing using the streptavidin/peroxidase method and the monoclonal antibody (moAb) MIB-1 to the Ki-67 antigen. The authors assessed proliferative labelling index (LI) from a series of surgically removed meningiomas using immunohistochemical methods and MIB-1, and they correlated this index with clinical, radiological, and histological factors. No relationship was found between LI, sex, age, resection and histological grades, or volume. Symptoms, location, and peritumoural oedema did have a significant relationship to the MIB-1 LI. The symptomatic patients, i.e. those with tumours at the base of the skull and with GR3 peritumoural oedema (grade 3), had a greater chance of higher MIB-1 LI. It was proven that the increase of one unit in peritumoural oedema classification gave an increased risk of 3.312 and an LI greater than 3%. The authors also discuss the different methods of evaluating LIs in meningiomas, based on the available literature.     

Proliferation rate of intracranial meningiomas as defined by the monoclonal antibody MIB-1: correlation with peritumoural oedema and other clinicoradiological and histological characteristics

Paraffin-embedded surgical specimens from 55 meningiomas were immunostained after microwave processing using the streptavidin/peroxidase method and the monoclonal antibody (moAb) MIB-1 to the Ki-67 antigen. The authors assessed proliferative labelling index (LI) from a series of surgically removed meningiomas using immunohistochemical methods and MIB-1, and they correlated this index with clinical, radiological, and histological factors. No relationship was found between LI, sex, age, resection and histological grades, or volume. Symptoms, location, and peritumoural oedema did have a significant relationship to the MIB-1 LI. The symptomatic patients, i.e. those with tumours at the base of the skull and with GR3 peritumoural oedema (grade 3), had a greater chance of higher MIB-1 LI. It was proven that the increase of one unit in peritumoural oedema classification gave an increased risk of 3.312 and an LI greater than 3%. The authors also discuss the different methods of evaluating LIs in meningiomas, based on the available literature.     

Measurement of changes in brain water in man by magnetic resonance imaging

John Hunter was undoubtedly aware of the water content of normal brain tissue, and described cerebral oedema. The advent of nuclear magnetic resonance (NMR) shed new light on brain water, and the derivation of spatial information and hence images from NMR signals, has permitted studies of regional brain water in man in vivo. The initial study described here tested whether NMR longitudinal relaxation time (T1) correlates with brain water content in the cerebral cortex and white matter in man, and significant relationships have been demonstrated in cortex (r = 0.65, P less than 0.002) and white matter (r = 0.94, P less than 0.0001), the latter having narrow 95% confidence limits. The residual variance allows the prediction of water content from the T1 of white matter, measured from the image of a single patient, with an accuracy of +/- 4% of total tissue water with 95% confidence. In the further study described, the effects of dexamethasone and an infusion of 20% mannitol on brain water content has been assessed in patients with intrinsic cerebral tumours. Dexamethasone had no significant effect on the T1 of normal brain, oedematous peritumoural white matter, or tumour tissue. It must be concluded that the water content of these tissues is not changed by dexamethasone and that the clinical improvement seen in patients with cerebral tumours immediately after dexamethasone has to be explained by some mechanism other than a reduction in cerebral oedema. Mannitol did reduce the T1 of oedematous peritumoural white matter, and the T1 of tumour tissue, but did not change the T1 of normal brain significantly.(ABSTRACT TRUNCATED AT 250 WORDS)     

Predictive factors related to symptomatic venous infarction after meningioma surgery

Abstract Introduction. The incidence of venous infarction after surgical resection of meningioma is low, but its occurrence can necessitate additional surgical procedures and long hospital stay. In this study, we evaluated variables associated with venous infarction after meningioma surgery. Methods. Among 825 patients with intracranial meningiomas who underwent microsurgical resection between January 1993 and March 2011, 27 (3.3%) presented with neurological deterioration due to postoperative venous infarction. The following factors were included in the statistical analysis to determine their association with venous infarction: sex, age, location, relation to venous sinus, peritumoural oedema, size and degree of resection. Results. Incidence of venous infarction was 6.8% with large meningiomas (size ≥?4 cm), but with small (size 相似文献   

Defining the Role of Stereotactic Radiosurgery Versus Microsurgery in the Treatment of Single Brain Metastases

Summary  Stereotactic radiosurgery (RS) and surgery have proved to be effective treatment modalities for brain metastasis. We followed 133 patients whose treatment for intracranial disease was either RS or a single surgical resection at the University of Vienna from August 1992 through October 1996. All patients who received additional Whole Brain Radiotherapy were included. This was a retrospective, case-control study comparing these treatment modalities.  Sixty-seven patients were treated by RS and 66 patients were treated by microsurgery. The median size of the treated lesions for RS patients was 7800 mm³, and 12500 mm³ for microsurgery patients, respectively. The median dose delivered to the tumour margin for RS patients was 17 gray.  The median survival for patients after RS was 12 months, and 9 months for patients after microsurgery. This difference was not statistically significant (p=0.19). Comparison of local tumour control, defined as absence of regrowth of a treated lesion, showed that tumours following RS had a preferred local control rate (p<0.05). Univariate and multivariate analysis showed that this fact was due to a greater response rate of “radioresistant” metastasis to RS (p<0.005). Postradiosurgical complications included the onset of peritumoural oedema (n=5) and radiation necrosis (n=1). Two patients after microsurgery experienced local wound infection. One postoperative death occurred due to pulmonary embolism in this group.  On the basis of our data we conclude that RS and microsurgery combined with Whole Brain Radiotherapy are comparable modalities in treating single brain metastasis. Concerning morbidity and local tumour control, in particular in cases of “radioresistant” primary tumours, RS is superior. Therefore we advocate RS except for cases of large tumours (>3 cm in maximum diameter) and for those with mass effect.     

Elevated peritumoural rCBV values as a mean to differentiate metastases from high-grade gliomas

Purpose  

Increased relative cerebral blood volume (rCBV) was previously found in peritumoural oedema of glioblastomas (GBM). Supposing that peritumoural rCBV is not increased in metastases, we aimed to evaluate whether rCBV values of the whole peritumoural area are accurate to differentiate solitary metastasis from GBM irrespective of the peritumoural oedema.     

Formation and propagation of brain oedema fluid around human brain metastases. A CT study

Summary Computerized tomography (CT) was used to examine the timecourse of the propagation of extravasated contrast medium from small brain metastases into the peritumoural oedematous white matter, following infusion of 200 ml of meglumine amidtrizoate for 3 hours. Four patients with a metastatic brain tumour were examined. CT scans at identical levels were taken 1.5, 3, 6, 9, and 12 hours after start of contrast infusion. Following 4–7 days of dexamethasone treatment (8–12mg/day i.v.) the examination was repeated. A contrast-enhanced area was observed surrounding the clearly delineated tumours, expanding gradually in a circular fashion into the peritumoural white matter oedema. The expanding circular enhancement was measured planimetrically on the various scans. From these values, the increase in radius/hr respectively in volume/hr was calculated, assuming a spherical geometry. This enabled a determination of the rate of oedema fluid formation and of the speed of oedema fluid propagation. The formation rate of oedema fluid amounted to 0.5–3.2ml/hour and the speed of oedema fluid spreading to 1.9 mm/hour. Following treatment with dexamethasone the formation rate of oedema fluid is reduced by 30–50%. The important clinical implications of these new findings are discussed.     

Effect of Hyperosmotic Solutions on Human Brain Tumour Vasculature

Summary  Reversible opening of the blood-brain barrier (BBB) has been used to increase delivery of chemotherapeutic agents into brain tumours, but it is complicated and requires general anaesthesia. Without affecting the normal BBB, and avoiding the complications of BBB modification by hyperosmotic solution, we tried an adequate minimal BBB disruption in brain tumours. Although the effect of BBB disruption on normal brain has been described, there are no reports of the effect of an impaired BBB on microcirculation. In this study, four patients underwent surgical resection of a glioblastoma multiforme (GM; n=1), astrocytoma (n=2), or metastatic brain tumour (n=1). Epicerebral microcirculation was observed in the operative field. Serial fluorescein microangiograms of the tumour and peritumoural area were obtained before and after BBB disruption was introduced intra-operatively by retrograde infusion of mannitol introducing a catheter via the temporal superficial artery back to the carotid bifurcation. On the initial microangiogram, staining by the fluorescein dye was observed in the GM and metastatic tumour but not in the astrocytoma; no extravasation of fluorescein dye was observed in the peritumoural areas. After BBB disruption, fluorescein perfusion increased and extravasation of fluorescein dye from the venules was observed in the GM and the metastatic tumour and in the peritumoural area of both lesions; BBB disruption started from venules in the peritumoural area without affecting the normal brain. However, such effects were not observed in the astrocytomas after BBB disruption nor in normal brain tissue in any patient. It appears that the integrity of the BBB is less stable in the peritumoural area of GM and metastatic brain tumours than it is in astrocytomas or normal brain. Osmotic BBB disruption may offer a method for achieving global delivery of therapeutic agents to brain tumours and peritumoural areas.     

Factors affecting the extension of peritumoural brain oedema. A CT-study

Summary In human brain tumours the extension of peritumoural brain oedema may vary considerably. 37 brain tumours of various pathology and 2 abscesses were examined to identify the factors and mechanisms responsible for the oedema spreading. Peritumoural oedema profiles were determined towards the white matter and ventricle by measuring the CT-numbers of consecutive tissue blocks of 3.0–3.6 mm from the tumour to the normal white matter or the ventricle. It was found that neither the size of the tumour nor the histology has a close relationship to the amount of peritumoural oedema. The distance of oedema spreading rather is determined by the amount of fluid accumulation in the white matter immediately bordering the tumour. This relationship corresponds to a semilogarithmic function and represents the relation between the tumour-adjacent accumulation of extracellular fluid volume and the distance of extracellular fluid movement. The analysis of this relation leads to the suggestion that pressure gradients and bulk flow are involved in the development of human peritumoural oedema.     

Prognostic Value of Vascular Endothelial Growth Factor and its Receptors Flt-1 and Flk-1 in Astrocytic Tumours

Summary  Background. Vascular endothelial growth factor (VEGF)/vascular permeability factor (VPF) is an important regulator of angiogenesis and vascular permeability.  Method. We examined immunohistochemically expressions of VEGF and its corresponding receptors Flt-1 and Flk-1 in a series of 50 astrocytic tumours, and correlated their expressions with the degree of angiogenesis, brain edema and prognosis.  Findings. There were significant relationships between VEGF, Flk-1 expressions and glioma malignancy grading, intratumoural vascularity and peritumoural brain edema, respectively. Patients with VEGF positive low grade astrocytoma and glioblastoma multiforme had a significantly shorter mean overall survival time than those with negative tumours (P=0.0010 and 0.0180, respectively). Flk-1 is also a significant prognostic factor within each tumour grade, which has a negative impact on overall survival. Additionally, overexpression of VEGF and Flk-1 were significantly associated with earlier recurrence in patients with low grade astrocytomas (P=0.0018 and 0.0240, respectively).  Interpretation. It is possible to subcategorize each grade of astrocytic tumours based on their VEGF and Flk-1 staining pattern, which may be crucial in predicting the biological behavior of tumours and thus provide useful information with regard to adequate treatment.     

Corticosteroid therapy of experimental tumour oedema

Summary Experimental brain tumours were produced in cats by stereotactic implantation of 4 million suspended cells of a rat glioma clone into the internal capsule. Three weeks after implantation a spherical tumour developed with a diameter of up to 10 mm which was surrounded by vasogenic white matter oedema. In untreated animals water content in the peritumoural white matter increased from 69.1 ± 0.9 to 80.0 ± 0.8 ml/100 g w. w., and regional blood flow reciprocally decreased from 32.2. ± 5.6 to 18.9 ± 0.05 ml/100 g/min. A single injection of a crystalline suspension of 10 mg/kg dexamethasone given intramuscularly one week before the animals were killed, led to a significant amelioration of brain oedema. Peritumoural white matter water content decreased to 73.0 ± 0.5 ml/100 g w. w. and blood flow rose to 35.7 ± 2.8 ml/100 g/min. These changes were accompanied by parallel shifts of electrolyte content but they did not correlate with EEG activity, as assessed by Fourier frequency analysis. Corticosteroids did not prevent extravasation of peroxidase or Evans blue across the tumour vessels. The beneficial effect, therefore, is attributed to either an acceleration of resorption or an inhibition of the spread of oedema from the tumour into the peritumoural brain tissue.     

Spinal meningiomas: a 20-year review

The long-term outcome of 78 patients with spinal meningiomas operated on over 20 years at a single neurosurgical unit was analysed. Age, sex and tumour location were similar to those reported by others. Overall, 95% of our patents were independently mobile postoperatively, despite 25% of the group being unable to walk before operation, including four paraplegic patients. Only two tumours were entirely extradural, and a further two were both intra- and extradural. In all cases, tumour exposure was by posterior laminectomy, without recourse to more complex approaches. Complete tumour resection was achieved in 77 (98%) of cases. The dural attachment was excised in 20 cases and diathermy was applied in 58. There was one recurrence, 14 years after the original surgery. Complex and technically challenging surgical approaches are unnecessary to obtain complete removal even for anteriorly placed tumours. Excision of the dural base would seem unnecessary to attain a low recurrence rate.     

The Pathogenesis of Tumour Associated Epilepsy

Tumour associated epilepsy (TAE) is a poorly understood manifestation of many gliomas, meningiomas and metastatic brain tumours that has important clinical and social implications. Etiological mechanisms underlying tumour associated epilepsy include theories invoking peritumoural amino acid disturbances, local metabolic imbalances, cerebral oedema, pH abnormalities, morphological changes in the neuropil, changes in neuronal and glial enzyme and protein expression and altered immunological activity. It has also been suggested that the pathology involves perturbations in distribution and function of the NMDA subclass of glutamate receptors. The often capricious response of the seizure disorder following removal of the causative neoplasms suggests multiple factors are involved. Further understanding about the pathogenesis of TAE will await the development and characterisation of suitable animal models that demonstrate the clinical manifestations and physiological changes comparable to those seen in human cerebral tumours. With such a model it is hoped that progress may one day be made in understanding and subsequently treating this debilitating clinical problem.     

Microcystic meningiomas: radiological characteristics of 16 cases

Summary Background. As a rare subtype of meningioma, only a few reports deal with radiological characteristics of microcystic meningiomas and the problem remains controversial. The authors have analyzed the radiological findings of a series of microcystic meningiomas with a special focus on magnetic resonance images (MRI) and conventional angiography.Method. Sixteen patients of histologically proven microcystic meningiomas were included. Analysis of preoperative MRI including signal intensity characteristics, enhancement patterns and peritumoural edema were performed and correlated with angiographic and histological findings. Peritumoural edema was graded using edema index (EI) which was defined as the ratio of V_E/V_T.Findings. The tumours were uniformly visualized as a high-signal mass lesion in T2-weighted images and as a low-signal mass lesion in T1-weighted images regardless of tumour vascularity shown by angiography. T2-weighted images revealed that peritumoural brain edema was severe in 11, moderate in 1, mild in 2 and negligible in 2 patients and this was closely related to the co-existence of irregular tumour marginal enhancement. However, other features failed to distinguish these lesions from other subtypes of meningioma.Conclusions. The cases presented demonstrate that characteristic MRI findings suggestive of microcystic meningiomas are; (1) low signal intensity mass in T1- and high signal intensity mass in T2-weighted images; (2) high incidence of peritumoural edema.     

Changes in cerebral tissue oxygen saturation during anaesthetic‐induced hypotension: an interpretation based on neurovascular coupling and cerebral autoregulation

There is currently no consensus regarding how to intervene in anaesthetic‐induced hypotension. Whether or not the balance between cerebral oxygen supply and demand is maintained lacks adequate elucidation. It is thus intriguing to explore how cerebral tissue oxygen saturation is affected by anaesthetic‐induced hypotension. Thirty‐three patients scheduled for elective non‐neurosurgical procedures were included in this study. Physiological measurements were performed immediately before induction with propofol and fentanyl and after tracheal intubation. Mean (SD) Bispectral index decreased from 84.3 (9.3) to 24.4 (8.0) (p < 0.001). Mean arterial pressure decreased from 84.4 (10.6) mmHg to 53.6 (11.4) mmHg (p < 0.001). However, cerebral tissue oxygen saturation remained stable (67.0 (9.4) % vs 67.5 (7.8) %, p = 0.6). These results imply that the fine balance between cerebral oxygen supply and demand is not disrupted by anaesthetic‐induced hypotension. An interpretation based on neurovascular coupling and cerebral autoregulation is proposed.