Histologically classified venous angiomas of the brain: a controversy

An Illustrative Review of the Pathomechanisms of Symptomatic Developmental Venous Anomalies

OBJECTIVE

Symptomatic developmental venous anomalies (DVAs) are rare. Here, we illustrate the varied clinicoradiologic profiles of symptomatic DVAs and contemplate the mechanisms that render these (allegedly) benign entities symptomatic supported by a review of literature.

METHODS

Institutional databases were searched to identify cases of symptomatic DVAs. Clinical and imaging (angiographic and cross-sectional) data of 9 cases with 11 neurovascular symptoms consequent to inflow/outflow perturbations and mechanical obstruction that manifested because of the strategic topography of underlying DVAs were analyzed. A review of the existing literature on DVAs in agreement with our case series was performed on publications retrieved from the PubMed database.

RESULTS

Symptoms secondary to venous hypertension arising from flow-related perturbations were broadly divided into those arising from restricted outflow and increased inflow. Restricted outflow occurred because of collector vein stenosis (n = 2) and collector vein/DVA thrombosis (n = 3), whereas the latter pathomechanism was initiated by arterialized/transitional DVAs (n = 2). A mechanical/obstructive pathomechanism culminating in moderate supratentorial ventriculomegaly was noted in 1 case. One patient was given a diagnosis of hemorrhage associated with a cavernoma.

CONCLUSIONS

Awareness and contextualization of potential flow-related perturbations and mechanical insults that render DVAs symptomatic aid in accurate diagnosis, management, and prognostication.

Case report: Delayed outflow obstruction of a DVA: A rare complication of brainstem cavernoma surgery

Introduction

Developmental venous anomalies (DVAs) are considered variants of normal transmedullary veins. Their association with cavernous malformations is reported to increase the risk of hemorrhage. Expert consensus recommends meticulous planning with MR imaging, use of anatomical “safe zones”, intraoperative monitoring of long tracts and cranial nerve nuclei, and preservation of the DVA as key to avoiding complications in brainstem cavernoma microsurgery. Symptomatic outflow restriction of DVA is rare, with the few reported cases in the literature restricted to DVAs in the supratentorial compartment.

Case

We present a case report of the resection of a pontine cavernoma complicated by delayed outflow obstruction of the associated DVA. A female patient in her 20's presented with progressive left-sided hemisensory disturbance and mild hemiparesis. MRI revealed two pontine cavernomas associated with interconnected DVA and hematoma. The symptomatic cavernoma was resected via the infrafacial corridor. Despite the preservation of the DVA, the patient developed delayed deterioration secondary to venous hemorrhagic infarction. We discuss the imaging and surgical anatomy pertinent to brainstem cavernoma surgery, as well as the literature exploring the management of symptomatic infratentorial DVA occlusion.

Conclusion

Delayed symptomatic pontine venous congestive edema is extremely rare following cavernoma surgery. DVA outflow restriction from a post-operative cavity, intraoperative manipulation, and intrinsic hypercoagulability from COVID-10 infection are potential pathophysiological factors. Improved knowledge of DVAs, brainstem venous anatomy, and “safe entry zones” will further elucidate the etiology of and the efficacious treatment for this complication.

Different Aspects on Clinical Presentation of Developmental Venous Anomalies: Are They as Benign as Known? A Single Center Experience

BACKGROUND

Cerebral developmental venous anomalies (DVAs) are frequently diagnosed incidentally owing to the advances in neuroimaging. They are regarded as clinically insignificant due to their supposed quiescent existence which the authors aimed to contradict in this paper.

AIM

In the aim of constituting a better understanding of clinical presentation of DVAs and making an estimation regarding the probability of resulting in a hemorrhage, the authors presented their experiences with a case series of DVAs.

METHODS

A retrospective analysis was carried out among patients who underwent brain MRI in a radiology department of a university between January of 2019 and January of 2020.

RESULTS

A total of 101 patients with DVA were extracted. 38 patients had isolated DVAs, while 63 patients had various accompanying cerebral pathologies, mostly cavernomas (39 patients) and AVMs (11 patients). The main complaints leading investigation were headache, dizziness, ataxia, nausea\vomiting, seizures and focal neurological deficits. 41 patients were truly symptomatic with indicative findings of seizures, neurological deficits or intracranial hemorrhages, and 12 of them had solitary DVAs. 22 patients presented with hemorrhages, and of them, 10 had only DVA, while the rest had some associated lesions, most often cavernoma. Of 22 patients with hemorrhage, 5 were operated, 5 were applied radiosurgery; while the rest were followed without any intervention.

CONCLUSION

Although the symptoms in patients with DVA are generally charged on other associated pathologies, the fact that isolated DVAs may occasionally be problematic in the range of minor symptoms and severe hemorrhage should not be underestimated.

Surgically Treated Epilepsy due to Developmental Venous Anomaly of the Brain: Case Report and Review of the Literature

BACKGROUND

A congenital malformation of the brain vessels, developmental venous anomaly (DVA) is considered a benign lesion, requiring no intervention unless symptomatic. Epilepsy is a well-known clinical manifestation of DVA. Successful surgery for DVA-associated epilepsy with has been sporadically reported in the literature; however, in all published cases, the anomaly was left intact along with the accompanying lesion. Here we present a surgical case of DVA located in the vicinity of the motor cortex causing drug-resistant simple partial epilepsy.

CASE DESCRIPTION

A 34-year-old man was referred due to medically intractable simple partial seizures. He was found to have DVA anterior to the motor cortex that was surgically removed. Following the surgical resection, the patient's seizures stopped, and there were no long-term complications of the procedure.

CONCLUSIONS

DVA removal can be performed in selected cases, but more studies are needed to assess the complication rate.

Isolated hemorrhagic arterialized DVAs: revisiting symptomatic DVAs

We aim to present here a small case series of symptomatic isolated hemorrhagic arterialized developmental venous anomalies (sDVAs) with a larger goal of revisiting the classification based on patho-mechanisms plus emphasizing angiographic features coupled with CT and MRI. Typically, DVA is an incidental and silent abnormality on neuroimaging. Understanding its morphology in terms of arterialization and relationship with other entities is crucial for management. One adult and two pediatric cases presented with acute or sub-acute hemorrhage in the cerebellum or thalamus. Morphologic characterization on cross-sectional imaging and catheter angiography confirmed the integrated diagnosis of "symptomatic isolated hemorrhagic arterialized DVAs with deeper or superficial venous drainage". Conservative management was adopted in all cases. We emphasize the following classification and approach for symptomatic DVAs: (1) congestive isolated arterialized sDVAs, (2) congestive isolated resistive sDVAs, (3) coexisting sDVAs (with AVM or cavernous malformation), (4) compressive sDVAs (compressive effects), and (5) idiopathic DVAs. Like our three cases, ganglionic and infratentorial DVAs have higher propensity of hemorrhage, compressive effects, and usually harbor deeper venous drainage. Typical "caput medusae" as dominant collector vein on cross-sectional imaging is crucial to complement and even confirm the diagnosis of DVA before catheter angiography in sDVAs. Capillary stain or early opacification of DVAs is a marker of arteriovenous shunting in arterialized sDVAs. Recognition of this entity is crucial as treatment is usually conservative.

Metabolic Changes of Brain Developmental Venous Anomalies on 18F-FDG-PET

RATIONALE AND OBJECTIVES

To determine the metabolic effects of developmental venous anomalies (DVAs) and to correlate those effects with conventional magnetic resonance imaging (MRI) findings.

MATERIALS AND METHODS

We conducted a retrospective review of MRI and brain 18F-fluorodeoxyglucose positron emission tomography (¹⁸F-FDG-PET) examinations in subjects with DVAs. Conventional MRI was used to determine DVA number, location, size, and associated parenchymal findings such as atrophy, hemorrhage, cavernoma, capillary telangiectasia, cortical dysplasia/polymicrogyria, and white matter signal abnormality. Qualitative and quantitative measures of relative metabolism in the drainage territory of the DVA were measured on ¹⁸F-FDG-PET.

RESULTS

Fifty-four subjects with 57 DVAs were included in the analysis. 38% were associated with qualitative and quantitative metabolic abnormalities on ¹⁸F-FDG-PET, with decreased metabolism in the parenchyma surrounding all but one of these DVAs. DVAs draining gray matter were significantly more likely to be hypometabolic than those draining only white matter, suggesting that the metabolic effects of DVAs may be underestimated on ¹⁸F-FDG-PET.

CONCLUSION

Altered metabolism is seen in the drainage territory of a significant proportion of DVAs, suggesting that these anomalies are vascular lesions with abnormal physiologic features.

Coexistent Cerebral Cavernous Malformation and Developmental Venous Anomaly: Does an Aggressive Natural History Always Call for Surgical Intervention?

Coexistence of cerebral cavernous malformations (CMs) and developmental venous anomaly (DVA) represents the most common form of mixed intracranial vascular malformations. Existing literature supports not only a possible causative role of DVA for de novo CMs but also a potentially detrimental effect on an associated CM, increasing the chances of hemorrhagic complications and growth in the latter. A 52-year-old gentleman presented to us with a 17-year long history of simple motor seizures on the left faciobrachial region. On magnetic resonance imaging (MRI) of the head, a 1.5 cm × 1.5 cm CM without any evidence of recent hemorrhage was identified in the left high frontal premotor area. There was a linear enhancement in the adjoining superior frontal sulcus on contrast MRI. On intra-arterial angiogram, this hyperintensity was confirmed to be a venous channel draining into the superior sagittal sinus. Thus, a diagnosis of cavernoma associated with a DVA was made. The patient was advised conservative treatment and he was doing well at follow-up. Unless diligently looked for, DVA associated with CM may be easily missed. The coexistence has pathophysiological and management implications. Despite the reported aggressive natural history, there is a scope for conservative treatment for these complex vascular malformations.

Endoscopic management of a cavernous malformation on the floor of third ventricle and aqueduct of Sylvius: Technical case report and review of the literature

Background:

Intraventricular cavernous malformations are unusual intracranial vascular malformations; their deep anatomical location complicates their surgical management. Microsurgical approaches are the gold standard approaches for the resection of ventricular lesions, however, they imply considerable neurovascular risks.

Case Description:

A 51-year-old patient presented with acute headache, diplopia, vertigo, blurred vision, and a depressed level of consciousness. A ventricular hemorrhage was treated with a ventriculostomy and the patient was discharged without hydrocephalus. After 11 days, he developed ataxia, diplopia, and a depressed level of consciousness. The patient was diagnosed with hydrocephalus secondary to the previous third ventricle hemorrhage. An endoscopic exploration using a 30° rigid ventricular endoscope was performed; after the third ventriculostomy, an intraventricular cavernous malformation located on the floor of the third ventricle and the aqueduct of Sylvius was resected.

Conclusions:

Three days after the surgery, magnetic resonance imaging demonstrated a gross total resection and adequate third ventriculostomy flow. One year after the surgery, the patient was asymptomatic. Neuroendoscopy has evolved towards minimally invasiveness, and in selected cases is an equally effective surgical approach to ventricular lesions. It provides minimal cerebral cortex disruption and vascular manipulation.

Novel functions of CCM1 delimit the relationship of PTB/PH domains

BACKGROUND

Three NPXY motifs and one FERM domain in CCM1 makes it a versatile scaffold protein for tethering the signaling components together within the CCM signaling complex (CSC). The cellular role of CCM1 protein remains inadequately expounded. Both phosphotyrosine binding (PTB) and pleckstrin homology (PH) domains were recognized as structurally related but functionally distinct domains.

METHODS

By utilizing molecular cloning, protein binding assays and RT-qPCR to identify novel cellular partners of CCM1 and its cellular expression patterns; by screening candidate PTB/PH proteins and subsequently structurally simulation in combining with current X-ray crystallography and NMR data to defined the essential structure of PTB/PH domain for NPXY-binding and the relationship among PTB, PH and FERM domain(s).

RESULTS

We identified a group of 28 novel cellular partners of CCM1, all of which contain either PTB or PH domain(s), and developed a novel classification system for these PTB/PH proteins based on their relationship with different NPXY motifs of CCM1. Our results demonstrated that CCM1 has a wide spectrum of binding to different PTB/PH proteins and perpetuates their specificity to interact with certain PTB/PH domains through selective combination of three NPXY motifs. We also demonstrated that CCM1 can be assembled into oligomers through intermolecular interaction between its F3 lobe in FERM domain and one of the three NPXY motifs. Despite being embedded in FERM domain as F3 lobe, F3 module acts as a fully functional PH domain to interact with NPXY motif. The most salient feature of the study was that both PTB and PH domains are structurally and functionally comparable, suggesting that PTB domain is likely evolved from PH domain with polymorphic structural additions at its N-terminus.

CONCLUSIONS

A new β1A-strand of the PTB domain was discovered and new minimum structural requirement of PTB/PH domain for NPXY motif-binding was determined. Based on our data, a novel theory of structure, function and relationship of PTB, PH and FERM domains has been proposed, which extends the importance of the NPXY-PTB/PH interaction on the CSC signaling and/or other cell receptors with great potential pointing to new therapeutic strategies.

GENERAL SIGNIFICANCE

The study provides new insight into the structural characteristics of PTB/PH domains, essential structural elements of PTB/PH domain required for NPXY motif-binding, and function and relationship among PTB, PH and FERM domains.

The Management of Symptomatic Cerebral Developmental Venous Anomalies: A Clinical Experience of 43 Cases

Background

Developmental venous anomalies (DVAs) are rare vascular diseases becoming more frequently diagnosed. Most patients with DVAs have no clinical symptoms with the exception of a few patients with epilepsy, intracranial hemorrhage, or neuro-function deficit. There is still controversy with respect to treatment strategies for symptomatic DVAs.

Material/Methods

Forty-three cases of symptomatic DVAs from January 2006 to October 2015 were retrospectively reviewed and the imaging characteristics of DVAs by CT, MRI, and DSA and the treatment modalities for DVAs were studied.

Results

Typical imaging characteristics of symptomatic DVAs were wedge or umbrella-shaped collections of dilated medullary veins converging in an enlarged subependymal or transcortical collecting vein, draining to the superficial or deep vein system. Based on location and draining vein features, symptomatic DVAs were tentatively classified into six different subtypes. Of the 43 cases, 19 were treated by surgical methods and 24 were treated conservatively.

Conclusions

We concluded that the rate of accompanying abnormalities in cases of symptomatic DVAs was high. Intracerebral hemorrhage was usually attributed to associated CMs or AVMs. The associated lesions and the branches responsible for bleeding could be resected while preserving the collecting vein as far as possible.

Developmental Venous Anomaly: Benign or Not Benign

Developmental venous anomalies (DVAs), previously called venous angiomas, are the most frequently encountered cerebral vascular malformations. However, DVA is considered to be rather an extreme developmental anatomical variation of medullary veins than true malformation. DVAs are composed of dilated medullary veins converging centripetally into a large collecting venous system that drains into the superficial or deep venous system. Their etiology and mechanism are generally accepted that DVAs result from the focal arrest of the normal parenchymal vein development or occlusion of the medullary veins as a compensatory venous system. DVAs per se are benign and asymptomatic except for under certain unusual conditions. The pathomechanisms of symptomatic DVAs are divided into mechanical, flow-related causes, and idiopathic. However, in cases of DVAs associated with hemorrhage, cavernous malformations (CMs) are most often the cause rather than DVAs themselves. The coexistence of CM and DVA is common. There are some possibilities that DVA affects the formation and clinical course of CM because CM related to DVA is generally located within the drainage territory of DVA and is more aggressive than isolated CM in the literature. Brain parenchymal abnormalities surrounding DVA and cerebral varix have also been reported. These phenomena are considered to be the result of venous hypertension associated with DVAs. With the advance of diagnostic imagings, perfusion study supports this hypothesis demonstrating that some DVAs have venous congestion pattern. Although DVAs should be considered benign and clinically silent, they can have potential venous hypertension and can be vulnerable to hemodynamic changes.

The Associated Venous Anomalies Variant and Adjacent Brain Function on Iron Sensitive Image Indicate Surgical Risk of Cavernous Malformation

The cavernous malformations (CMs) associated with venous anomalies (VAs) are now being described with increasing frequency. Assessment of the associated VAs is overlooked in surgical management of the CM. The clinical profiles of CMs with VAs were reviewed to investigate the value of T₂*gradient echo (GRE)/susceptibility weighted imaging (SWI) in surgical risk evaluation. Twenty-six patients with symptomatic CMs associated with VAs between 2008 and 2013 were identified. Demographic, clinical, and radiological data were reviewed and functional outcomes were assessed using the modified Rankin Scale (mRS). The T₂*GRE/SWI could allow more accurate evaluation of the boundary and drainage vicinity of VAs than contrast-enhanced images (6 vs. 2 patients with VAs on the eloquent region). Patients with VAs adjacent to eloquent brain showed poorer outcomes than those who had VAs in non-eloquent areas (P = 0.005), while the CMs adjacent to eloquent brain did not correlated with poor outcomes (P = 0.15). Type I and III variants of VAs were also significantly associated with poor outcomes, compared with type II variant (P = 0.002). Careful evaluation of VAs variant type and the association between VAs and eloquent brain is helpful for the management of CMs associated with VAs. We recommend T₂*GRE/SWI in patients with CMs to assess the associated VAs. The evaluation of VA drainage vicinity on T₂*GRE/SWI would be more useful for designing treatment strategies and risk stratification.

Neuroimaging diagnosis of pineal region tumors-quest for pathognomonic finding of germinoma

INTRODUCTION

Our study aimed to elucidate the imaging features for the differentiation of pineal germinoma and other pineal region tumors.

METHODS

Image data sets of computed tomographic (CT) scan and magnetic resonance imaging (MRI) data of 93 pineal region tumors including 33 germinomas, 30 nongerminomatous germ cell tumors (NGGCTs), 20 pineal parenchymal tumors (PPTs), and 10 miscellaneous tumors of pineal region were reviewed. Imaging features on CT and MRI were qualitatively assessed by three readers. To know the reasons for morphological differences between germinomas and NGGCTs, histological investigation was done.

RESULTS

Localized calcification was seen in more than 70 % of germ cells tumors (GCTs: germinomas and NGGCTs) while it was scattered in more than half of PPTs. Cystic components in tumors were most frequent in NGGCTs (62 %). Multiplicity of lesion was restricted to GCTs: 39.4 % in germinoma and 10.0 % in NGGCTs. Thick peritumoral edema was more frequent in germinoma than in NGGCT: 40.6 vs. 14.8 % (p=0.0433, Fisher's test). Bithalamic extension of tumor was seen in 78.8 % of germinomas. It was significantly rare in other groups of tumors (p<0.0001, Fisher's test). The relative collagen amount per unit area was significantly lower in germinoma than in NGGCTs.

CONCLUSION

By paying attention to characteristic features as bithalamic extension, thick peritumoral edema, calcification pattern, multiplicity, and their combination, the preoperative differential diagnosis of pineal germinoma will become more accurate.

Diffusion and perfusion MRI findings of the signal-intensity abnormalities of brain associated with developmental venous anomaly

BACKGROUND AND PURPOSE

Developmental venous anomalies are the most common intracranial vascular malformation. Increased signal-intensity on T2-FLAIR images in the areas drained by developmental venous anomalies are encountered occasionally on brain imaging studies. We evaluated diffusion and perfusion MR imaging findings of the abnormally high signal intensity associated with developmental venous anomalies to describe their pathophysiologic nature.

MATERIALS AND METHODS

We retrospectively reviewed imaging findings of 34 subjects with signal-intensity abnormalities associated with developmental venous anomalies. All subjects underwent brain MR imaging with contrast and diffusion and perfusion MR imaging. Regions of interest were placed covering abnormally high signal intensity around developmental venous anomalies on fluid-attenuated inversion recovery imaging, and the same ROIs were drawn on the corresponding sections of the diffusion and perfusion MR imaging. We measured the apparent diffusion coefficient, relative cerebral blood volume, relative mean transit time, and time-to-peak of the signal-intensity abnormalities around developmental venous anomalies and compared them with the contralateral normal white matter. The Mann-Whitney U test was used for statistical analysis.

RESULTS

The means of ADC, relative cerebral blood volume, relative mean transit time, and TTP of signal-intensity abnormalities around developmental venous anomalies were calculated as follows: 0.98 ± 0.13 10(-3)mm(2)/s, 195.67 ± 102.18 mL/100 g, 16.74 ± 7.38 seconds, and 11.65 ± 7.49 seconds, respectively. The values of normal WM were as follows: 0.74 ± 0.08 10(-3)mm(2)/s for ADC, 48.53 ± 22.85 mL/100 g for relative cerebral blood volume, 12.12 ± 4.27 seconds for relative mean transit time, and 8.35 ± 3.89 seconds for TTP. All values of ADC, relative cerebral blood volume, relative mean transit time, and TTP in the signal-intensity abnormalities around developmental venous anomalies were statistically higher than those of normal WM (All P < .001, respectively).

CONCLUSIONS

The diffusion and perfusion MR imaging findings of the signal-intensity abnormalities associated with developmental venous anomaly suggest that the nature of the lesion is vasogenic edema with congestion and delayed perfusion.

Cerebral vascular malformations in hereditary hemorrhagic telangiectasia

Object

Hereditary hemorrhagic telangiectasia (HHT) is a hereditary disorder characterized by mucocutaneous telangiectasias, frequent nosebleeds, and visceral arteriovenous malformations (AVMs). Few reports have outlined the prevalence of the various cerebral vascular malformations found in patients with HHT. The authors set out to define the prevalence of cerebral vascular malformations in a population of HHT patients who underwent imaging with 3-T imaging (MRI/MR angiography [MRA]) of the brain.

Methods

A retrospective review of prospectively collected data was carried out using a database of 372 HHT patients who were seen and examined at the Georgia Regents University HHT Center and screened with 3-T MRI/MRA. Data were tabulated for numbers and types of vascular malformations in this population.

Results

Arteriovenous malformations were identified in 7.7%, developmental venous anomalies in 4.3%, and cerebral aneurysms in 2.4% of HHT patients. The HHT AVMs tended to be supratentorial, small, and cortical in this series, findings consistent with other recent studies in the literature. An arteriovenous fistula, cavernous malformation, and capillary telangiectasia were identified in 0.5%, 1%, and 1.9% of HHT patients, respectively.

Conclusions

Few studies have investigated the prevalence of the various vascular malformations found in HHT patients screened with 3-T MRI/MRA of the brain. Hereditary hemorrhagic telangiectasia AVMs are more likely to be multiple and have a tendency toward small size and cortical location. As such, they are often treated using a single-modality therapy.

Neuropsychological functions and quality of life in survived patients with intracranial germ cell tumors after treatment

BACKGROUND

The notable survival chances of intracranial germ cell tumors (icGCTs) lead to a rising concern over long-term neurocognitive outcome. Yet, prior evidence related to this issue fails to provide a comprehensive examination of the effects of tumor location and radiotherapy. We attempt to explore their impacts on the neuropsychological functions and life quality in children with icGCT after multimodality treatments.

METHODS

A retrospective review of 56 patients diagnosed with icGCTs at age <20 and treated at the Taipei Veterans General Hospital was provided. Intelligence, memory, visual organization, attention, and executive function were assessed by neurocognitive tests; adaptation to life, emotional and behavioral changes, interpersonal relationships, and impact on the family were evaluated by parent-report instruments. Effects of tumor locations (germinomas and nongerminomatous malignant germ cell tumors in the pineal, suprasellar, and basal ganglia) and irradiation on these measurements were examined.

RESULTS

Patients with tumors in the basal ganglia region had lower full-scale IQs than those with tumors in the pineal or suprasellar regions. Subscores of intelligence scale and short-term retention of verbal and visual stimuli showed evident group differences, as did the quality of life and adaptive skills, particularly in psychosocial domains. Patients treated with whole-ventricular irradiation had better outcomes. Extensive irradiation field and high irradiation dosage influenced intellectual functions, concept crystallization, executive function, and memory.

CONCLUSIONS

Tumor location and irradiation field/dosage appear to be the crucial factors related to certain neuropsychological, emotional, and behavioral dysfunctions that in turn alter the quality of life in children with icGCTs who survive after treatment.

Hemodynamic effects of developmental venous anomalies with and without cavernous malformations

BACKGROUND AND PURPOSE

Association between developmental venous anomalies is well known, but remains unexplained. Our aim was to study possible hemodynamic differences around developmental venous anomalies with and without cavernous malformations.

MATERIALS AND METHODS

In this prospective study approved by the institutional review board, PWI was performed in 24 patients with 25 DVAs (10 with and 15 without CMs) who consented to participate. We calculated relative cerebral blood volume, relative cerebral blood flow, and relative mean transit time for the brain surrounding the DVA tributaries in reference to contralateral mirror image locations. Corresponding control values (cCBV, cCBF, and cMTT) were generated in a similar fashion for remote ipsilateral regions with normal venous drainage, also in reference to contralateral mirror image locations. Perfusion parameters for DVAs and control regions were tested for differences between groups with the t test for independent or paired samples (or the nonparametric equivalents). Similar testing was done for perfusion parameters for DVAs with and without CMs.

RESULTS

Normal-appearing brain surrounding DVAs showed increased rCBV (median = 2.98; range = 1.39-6.61), increased rCBF (median = 2.00, range = 0.79-4.43), and increased rMTT (mean = 1.46; 95% confidence interval, 1.32-1.59). These were significantly higher than median cCBV (0.99; 95% confidence interval, 0.89-1.06; P < .01), median cCBF (1.00; 95% confidence interval, 0.94-1.27; P < .01), and mean cMTT (1.00; 95% confidence interval, 0.98-1.02; P < .01), respectively. Mean rMTT (1.70; 95% confidence interval, 1.46-1.93) for DVAs with CMs was higher than mean rMTT (1.29; 95% confidence interval, 1.19-1.40; P < .01) for DVAs without CMs.

CONCLUSIONS

DVAs are strongly associated with altered hemodynamics. Significant differences in these hemodynamic alterations for DVAs with and without CMs suggest their possible role in the formation of CMs.

Developmental venous anomaly with contralateral impaired venous drainage in a 17-year-old male. A case report

Developmental venous anomalies (DVA) drain normal neural tissue and are mostly discovered incidentally. We describe a young patient with a left hemisphere superficial to deep DVA and right hemisphere venous outflow restriction presenting with a seizure. The right hemisphere drainage variation is not typical of a DVA but represents another drainage pattern on the border of normality.

Thrombosis of a developmental venous anomaly in inflammatory bowel disease: case report and radiologic follow-up

Developmental venous anomalies (DVAs) are benign embryologic vascular variants, and before the advent of computed tomography and magnetic resonance imaging were supposed to be rare conditions. Usually, DVAs are asymptomatic and accidentally discovered during routine brain imaging studies, but sometimes they can be the cause of disabling neurologic symptoms. We describe the clinical and neuroradiologic follow-up of a 62-year-old man with a history of inflammatory bowel disease (IBD) presenting with new onset epilepsy and intracranial hemorrhage caused by thrombosis of a DVA who fully recovered after treatment with oral anticoagulant therapy. Patients with IBD have an increased risk of thrombosis because of inflammatory activity and the hypercoagulable state. Here we describe the first case of DVA thrombosis in a patient with IBD, and we show clinical and neuroradiologic follow-up after anticoagulant therapy.

[Venous angioma with associated cerebellar haemorrhage]

Venous angiomas are a developmental anomaly in which embryonic venous drainage is still present into adulthood. They are usually asymptomatic and benign course but they can cause seizures and less commonly bleeding, usually associated to cavernous malformation. Normally, treatment is not necessary although bleeding, severe clinical and lesions in which it is possible a favourable approach, we can consider treatment. We show a case of a 11 years old boy with acute decrease level of consciousness. We observed hematoma in the right cerebellar hemisphere with radial tubular structures consistent with developmental venous anomaly. The hematoma was evacuated without a demonstrable other reason justifying the bleeding.

Medulloblastoma manifesting as sudden sensorineural hearing loss

We present a rare case of medulloblastoma which presented with unilateral sudden sensorineural hearing loss as an initial symptom. A 19-year-old man was admitted to our hospital with a chief complaint of dizziness and facial numbness on the right side. His illness had begun two years previously with sudden hearing loss on the right side, for which he had been treated as an idiopathic sudden hearing loss. Magnetic resonance imaging demonstrated abnormal signals located mainly in the right middle cerebellar peduncle. We performed partial resection of the tumor by suboccipital craniotomy. The histopathological diagnosis was medulloblastoma. Intrinsic brain tumor is an extremely rare cause of sudden sensorineural hearing loss and is therefore easily overlooked as was in the present case. The present case highlights not only the need to evaluate patients with sudden sensorineural hearing loss by magnetic resonance imaging but also the importance of paying attention to intrinsic lesions involving the brainstem. Although this condition like the presented case might be rare, intrinsic brain tumor should be considered as a potential cause of sudden sensorineural hearing loss, as it may be easily missed leading to a delay in appropriate treatment.

Descriptive epidemiology of pediatric intracranial neoplasms in Egypt

OBJECTIVE

The characteristics of 451 Egyptian children (aged 0-14 years) with primary intracranial neoplasms were investigated for demographic, clinical, topographical and pathological features using the most recent 2007 Classification of Central Nervous System Tumors.

PATIENTS AND METHODS

This was a retrospective study performed in the Departments of Pediatric Neurosurgery of the Cairo University Hospitals from 2005 to 2008.

RESULTS

There was a slight male predominance (51.4%) observed in our study, and the most affected age group was 5-9 years old (43.2%). Most of the tumors were confined to a single compartment (infratentorial in 49.7%, supratentorial in 46.6%), while 3.8% of the tumors involved multiple compartments. The most common intracranial tumors were astrocytomas (35%), medulloblastomas (18.8%), craniopharyngiomas (11.3%) and ependymomas (10%). Pilocytic astrocytomas constituted 55% of all astrocytomas and 19.3% of all brain tumors, only slightly ahead of medulloblastomas. Less common types were primitive neuroectodermal tumors (2.7%), followed by meningiomas, germ cell tumors and choroid plexus tumors (2.4% each). According to the International Classification of Diseases for Oncology Coding (ICD-O-4), benign, borderline and malignant tumors constituted 7.54, 36.14 and 56.32%, respectively.

CONCLUSION

The characteristics of pediatric intracranial tumors in Egypt are generally similar to those reported in the literature, with only minor differences.

Transcallosal interforniceal approach to pineal region tumors in 150 children

OBJECT

Pediatric pineal region tumors are very difficult to cure surgically. The authors used the transcallosal interforniceal approach in patients with these lesions.

METHODS

One hundred fifty children, 98 boys and 52 girls, with pineal region tumors underwent tumor resection via the transcallosal interforniceal approach in the pediatric neurosurgery ward of TianTan Hospital. The patients ranged in age from 1 to 15 years. Fifty-eight patients had mature teratomas; 57, immature teratomas; 14, astrocytomas; 3, glioblastomas; 4, pineoblastomas; 2, pineocytomas; 4, choriocarcinomas; 4, cavernous hemangiomas; 2, germ cell tumors; and 2, epidermoid cysts.

RESULTS

One hundred twenty-nine tumors were totally removed, 15 were subtotally removed, and 6 were partly removed. There were no deaths and no subsequent instances of disconnection syndrome. Short-term memory deficits appeared in 94 patients but resolved within 6 months in most; only a few patients retained persistent deficits. There were 2 patients with mutism that resolved within 10 days. Parinaud syndrome was observed in 45 patients after surgery; 21 of these cases had appeared preoperatively. The syndrome resolved within 6 months in 31 patients, while it remained in the other 14.

CONCLUSIONS

The transcallosal interforniceal approach appears to be a safe route for pineal region tumors in children, and complete resection can be achieved in the majority of patients.

Cerebral developmental venous anomalies

INTRODUCTION

Cerebral developmental venous anomalies (DVAs) are the most frequently encountered cerebral vascular malformation. As such, they are often observed incidentally during routine CT and MRI studies. Yet, what DVAs represent from a clinical perspective is frequently not common knowledge and DVAs, therefore, still generate uncertainty and concern amongst physicians. This article reviews our current understanding of developmental venous anomalies.

RESULTS

In the majority of cases, DVAs follow a benign clinical course. On rare occasions, DVAs become symptomatic generally due to an underlying associated vascular malformation such as cavernous malformations or thrombosis of the collecting vein. Rare forms of DVAs include arterialized DVAs and DVAs involved in the drainage of sinus pericranii, which warrant additional investigation by digital subtraction angiography. Cerebral abnormalities such as atrophy, white matter lesions and calcifications within the drainage territory of asymptomatic DVAs, are often identified on CT or MR imaging studies and likely represent secondary changes due to venous hypertension. There is increasing evidence that DVAs have a propensity for developing venous hypertension, which is thought to be the cause of associated cavernous malformations and parenchymal abnormalities.

CONCLUSIONS

DVAs represent variations of the normal cerebral venous angioarchitecture and by enlargement follow an uneventful clinical course. Complications can, however, occur and their management requires a thorough understanding of the nature of DVAs, including their frequent coexistence with other types of vascular malformation, and the existence of more complex but rare forms of presentation, such as the arterialized DVAs.

Epidemiology of primary brain and central nervous system tumors in Korea

OBJECTIVE

The aim of this report is to provide accurate nationwide epidemiologic data on primary central nervous system (CNS) tumors in Korea. Despite its importance, there are no accurate statistics on primary CNS tumors in Korea. We analyzed primary CNS tumors diagnosed in 2005 from the nationwide registry.

METHODS

Data on primary CNS tumors diagnosed in 2005 were collected from the Korean Central Cancer Registry and the Korean Brain Tumor Society. Crude and age-standardized rates were calculated in terms of gender, age, and histological type. Tumors of uncertain histology were investigated individually at the corresponding hospitals and had their diagnoses confirmed.

RESULTS

A total of 5,692 patients diagnosed with primary CNS tumors in 2005 were included in this study. CNS tumors occurred in females more often than in males (female to male, 1.43 : 1). The most common tumor was meningioma (31.2%). Glioblastoma accounted for 30.7% of all gliomas, and 19.3% of all malignant primary CNS tumors. In children under 19 years of age, both germ cell tumor and embryonal/primitive/medulloblastoma were the most common tumors.

CONCLUSION

This article is the first nationwide primary CNS tumor epidemiology report in Korea. Data from this study should provide valuable information regarding the understanding of primary CNS tumors epidemiology in Korea.

Developmental venous anomalies: appearance on whole-brain CT digital subtraction angiography and CT perfusion

Introduction

Developmental venous anomalies (DVA) consist of dilated intramedullary veins that converge into a large collecting vein. The appearance of these anomalies was evaluated on whole-brain computed tomography (CT) digital subtraction angiography (DSA) and CT perfusion (CTP) studies.

Methods

CT data sets of ten anonymized patients were retrospectively analyzed. Five patients had evidence of DVA and five age- and sex-matched controls were without known neurovascular abnormalities. CT angiograms, CT arterial-venous views, 4-D CT DSA and CTP maps were acquired on a dynamic volume imaging protocol on a 320-detector row CT scanner. Whole-brain CTP parameters were evaluated for cerebral blood flow (CBF), cerebral blood volume (CBV), time to peak (TTP), mean transit time (MTT), and delay. DSA was utilized to visualize DVA anatomy. Radiation dose was recorded from the scanner console.

Results

Increased CTP values were present in the DVA relative to the unaffected contralateral hemisphere of 48%, 32%, and 26%; and for the control group with matched hemispheric comparisons of 2%, −10%, and 9% for CBF, CBV, and MTT, respectively. Average effective radiation dose was 4.4 mSv.

Conclusion

Whole-brain DSA and CTP imaging can demonstrate a characteristic appearance of altered DVA hemodynamic parameters and capture the anomalies in superior cortices of the cerebrum and the cerebellum. Future research may identify the rare subsets of patients at increased risk of adverse outcomes secondary to the altered hemodynamics to facilitate tailored imaging surveillance and application of appropriate preventive therapeutic measures.

Cerebellar hemangioblastoma manifesting as hearing disturbance

A 49-year-old man presented with a rare case of cerebellar hemangioblastoma manifesting as only hearing disturbance. He had suffered from hearing difficulty in the right ear for a few months. Magnetic resonance imaging revealed a cystic mass lesion with an internal fluid level and surrounding flow voids in the right cerebellopontine (CP) angle. Cerebral angiography disclosed a vascular-rich tumor fed by both the superior cerebellar and anterior inferior cerebellar arteries. En bloc resection of the tumor was planned under a preoperative diagnosis of cerebellar hemangioblastoma. The tumor protruded into the CP cistern and compressed cranial nerve VIII. The feeding arteries were meticulously coagulated and the tumor was successfully removed. The histological diagnosis was hemangioblastoma. After the operation, the patient's hearing acuity improved dramatically. Cerebellar hemangioblastoma should be considered in the differential diagnosis of CP angle tumors associated with hearing disturbance.

Perfusion-CT of developmental venous anomalies: typical and atypical hemodynamic patterns

This article reports perfusion-CT patterns that can be observed in patients with DVAs. In atypical DVAs, an abnormal venous congestion pattern with increased CBV, CBF and MTT can be observed in the vicinity of a DVA, and needs to be recognized and differentiated from other entities such as cerebral neoplasms or stroke. This pattern might help to stratify risks of associated complications such as hemorrhage.

DEVELOPMENTAL VENOUS ANOMALIES

DEVELOPMENTAL VENOUS ANOMALIES (DVAs), formerly known as venous angiomas, have become the most frequently diagnosed intracranial vascular malformation. DVAs are currently considered congenital cerebrovascular anomalies with mature venous walls that lack arterial or capillary elements. They are composed of radially arranged medullary veins, which converge in an enlarged transcortical or subependymal collector vein, and have characteristic appearances (caput medusae) on magnetic resonance imaging and angiography. DVAs were once thought to be rare lesions with substantial potential for intracerebral hemorrhage and considerable morbidity. The prevalence of incidental and asymptomatic DVAs has been more apparent since the advent of magnetic resonance imaging; recent cohort studies have challenged the once-held view of isolated DVAs as the cause of major neurological complications. The previously reported high incidence of intracerebral hemorrhage associated with DVAs is currently attributed to coexistent, angiographically occult cavernous malformations. Some patients may still have noteworthy neurological morbidity or die as a result of acute infarction or hemorrhage directly attributed to DVA thrombosis. DVAs can coexist with cavernous malformations and arteriovenous malformations. Such combination or transitional forms of malformations might suggest common pathways in pathogenesis. Recent data support a key role for DVAs in the pathogenesis of mixed vascular malformations.

Pathomechanisms of Symptomatic Developmental Venous Anomalies

Background and Purpose— Although it is generally accepted that developmental venous anomalies (DVAs) are benign vascular malformations, over the past years, we have seen patients with symptomatic DVAs. Therefore, we performed a retrospective study and a literature study to review how, when, and why DVAs can become clinically significant.

Methods— Charts and angiographic films of 17 patients with DVAs whose 18 vascular symptoms could be attributed to a DVA were selected from a neurovascular databank of our hospital. MRI had to be available to rule out any other associated disease. In the literature, 51 cases of well-documented symptomatic DVAs were found. Pathomechanisms were divided into mechanical and flow-related causes.

Results— Mechanical (obstructive or compressive) pathomechanisms accounted for 14 of 69 symptomatic patients resulting in hydrocephalus or nerve compression syndromes. Flow-related pathomechanisms (49 of 69 patients) could be subdivided into complications resulting from an increase of flow into the DVA (owing to an arteriovenous shunt using the DVA as the drainage route; n=19) or a decrease of outflow (n=26) or a remote shunt with increased venous pressure (n=4) leading to symptoms of venous congestion. In 6 cases, no specific pathomechanisms were detected.

Conclusions— Although DVAs should be considered benign, under rare circumstances, they can be symptomatic. DVAs, as extreme variations of normal venous drainage, may represent a more fragile venous drainage system that can be more easily affected by in- and outflow alterations. The integrity of the DVA needs to be preserved irrespective of the treatment that should be tailored to the specific pathomechanism.

Neurohypophyseal granulomatous germinoma invading the right cavernous sinus: case report and review of the literature

We encountered a rare case of neurohypophyseal germinoma with a prominent granulomatous reaction, which invaded the right cavernous sinus. The neuroimaging and histopathology features in this case were unique, distinguishing it from other types of suprasellar lesions. A 13-year-old boy presented with loss of appetite and polyuria; both symptoms were present for 1 year, and headache, general fatigue and blurred vision present for the prior 2 months. On admission, neurological examination indicated bitemporal hemianopsia and optic atrophy. Endocrinological exam showed panhypopituitarism. Tumor markers such as alpha-fetoprotein, human growth hormone, carcinoembryonic antigen, and placental alkaline phosphatase were negative. Brain CT revealed a suprasellar tumor with calcification. MR T(1)-weighted and T(2)-weighted images showed the tumor to be isointense to normal brain parenchyma and to be enhanced densely. The tumor also involved the right cavernous sinus, so that a biopsy was performed by the transsphenoidal approach. On pathologic examination of the specimen, typical large tumor cells with lymphocytic cell infiltration and prominent granulomatous reaction were observed. Neurohypophyseal granulomatous germinoma was diagnosed. Radiotherapy was performed with a total dose of 51 Gy and the tumor shrank remarkably. The patient returned to school under hormone replacement therapy.

Are gliomas preventable?

Gliomas are a family of primary central nervous system tumors of variable malignancy that are derived from supporting glia (astrocytes, oligodendrocytes, ependymal cells) or their progenitors/stem cells. There are two potential strategies to prevention: preventing gliomas from forming and preventing lower-grade gliomas from developing into higher-grade gliomas. Each would lower time-dependent mortality. Each also depends on an understanding of what causes gliomas so that these factors can be modulated. In this presentation, I will discuss primary prevention, chemoprevention, and screening. I will first focus on the known chromosomal, genetic, and protein changes associated with the different histologic varieties of glioma and the environmental, hereditary, and infectious/viral factors that may promote glioma development and malignant progression. I will discuss a number of clinical scenarios that eventuate from the known genetic patterns of these tumors and the changes in genetic patterns that reflect malignant progression. The basic thinking is that if one could prevent specific gene mutations and/or deletions or gains of specific chromosomes that lead to the development of low-grade (WHO 2) gliomas, then theoretically this would reduce the occurrence of high-grade (WHO 3 and 4) gliomas and hence the almost certain death that now is the fate of most patients with these tumors. In the case of de novo WHO 3 and 4 tumors, being able to prevent or counter specific gene mutations and/or the deletion of specific chromosomes would in itself reduce the occurrence of these gliomas and increase survival. Alternatively, a curative treatment for low-grade glioma that prevents these chromosomal/gene changes would prevent some glioblastomas (WHO 4) from forming and would have the same desired effect on survival. Obviously, for the latter to be achieved, we must also be able to diagnose and treat low-grade gliomas earlier.

Effect of gefitinib on brain metastases from non-small cell lung cancer

Two patients with non-small cell lung cancer presented with multiple brain metastases. They received gefitinib orally for the treatment of the primary lung lesions. About one month later, the brain metastases unexpectedly disappeared or became smaller. The patients survived without recurrence of brain metastases and growth of lung lesions for 3-4 years. Gefitinib is a selective epidermal growth factor receptor tyrosine kinase inhibitor and is approved for use in the treatment of non-small cell lung cancer. Gefitinib may be very effective for multiple brain metastases in patients with non-small cell lung cancer.

The association of venous developmental anomalies and cavernous malformations: pathophysiological, diagnostic, and surgical considerations

✓Developmental venous anomalies (DVAs) are often associated with intracranial cavernous malformations (CMs). The frequency of this association and the observation of de novo CMs located near a known, preexisting DVA raise speculations as to the possible etiopathogenetic relationship between the two. In this article, the authors review the recent literature dealing with the potential etiopathogenetic, prognostic, and therapeutic implications of the association between DVAs and CMs.

C-kit gene mutation: common and widely distributed in intracranial germinomas

OBJECT

Of the intracranial germ cell tumors (IGCTs), 10% of germinomas and most nongerminomatous tumors remain refractory to multimodality therapy. The authors investigated the mutation of c-kit and the expression of its product KIT in IGCTs to identify tumors susceptible to imatinib mesylate, a synthetic agent targeting KIT.

METHODS

The authors investigated 26 IGCTs, including 13 germinomas, five mixed germ cell tumors (MGCTs), four immature teratomas (ITs), and two each of yolk sac tumors and choriocarcinomas. These tumors were examined for the expression of KIT and CD34 by immunohistochemical analysis, and for mutations in exons 2, 8 to 11, 13, and 17 of c-kit. Strong KIT expression was found in the cell membrane of germinomas (100%) and germinomatous cells of MGCTs (80%), as well as in the cytoplasm of epithelial and smooth-muscle cells of ITs. The membranous expression of CD34 was found in the nongerminomatous tumor cells and the chondrocytes of MGCTs (60%), ITs (100%), and a choriocarcinoma (50%), but not in germinomas and germinomatous cells. A total of five missense mutations distributed in exons 2, 11, 13, and 17 of c-kit were detected in three (23%) of the 13 germinomas. The novel mutations E73K, T96M (both in exon 2), and A636V (in exon 13) were detected in a single tumor. The presence or type of c-kit mutation was not correlated with patient prognosis.

CONCLUSIONS

Immunohistochemical analysis of KIT expression is useful for the diagnosis of germinoma. This study may help in clarifying the pathogenesis of IGCTs and in identifying tumors susceptible to drugs targeting KIT.

Primary pediatric brain tumors: statistics of Taipei VGH, Taiwan (1975-2004)

BACKGROUND

The purpose of the current study was to investigate a hospital series of 986 cases of primary pediatric brain tumors in Taiwan.

METHODS

The authors reviewed the database of primary pediatric brain tumors in patients < 18 years of age collected in Taipei Veterans General Hospital (Taipei VGH) from 1975 to May 2004. Age and gender distribution, location, and classification of brain tumors were analyzed. Intracranial tumors with diagnostic imaging were included. Nontumoral lesions, cysts, and vascular malformations were excluded.

RESULTS

The mean age of these 986 patients was 7.8 years, and the male to female ratio was 1.4:1. Supratentorial (including pineal-quadrigeminal) located tumors (58.3%) was predominant to infratentorial tumors (41.1%). In these series, 886 patients had either histologic diagnosis (842 patients) or clinical diagnosis (44 patients). The most common 5 categories of tumors were astrocytic tumors (31.1%), germ cell tumors (14.0%), medulloblastomas (13.3%), craniopharyngiomas (8.3%), and ependymal tumors (5.8%). Atypical teratoid/rhabdoid tumors (AT/RTs), a rare but highly malignant tumor, were 2.1%. The high incidence of primary intracranial germ cell tumors correlated with reported series from Japan and Korea. For the remaining 100 patients without diagnostic classifications, the majority were most likely astrocytic tumors in brain stem.

CONCLUSIONS

The authors analyzed a large hospital series of primary brain tumors in children. Both histologically verified and unverified tumors were recruited to avoid selective bias. Although it was not a study of a population-based brain tumor registry, it could still be representative of primary pediatric brain tumors in Taiwan.

Cerebral Cavernous Malformations Associated with Venous Anomalies: Surgical Considerations

OBJECTIVE:

Once thought to be rare entities, mixed cerebrovascular malformations with pathological features of more than one type of malformation within the same lesion are now being recognized with increasing frequency. Their identification generates several hypotheses about common pathogenesis or causation-evolution among different types of lesions and leads to controversial discussion on therapeutic strategies.

METHODS:

Fifteen patients drawn from a consecutive series of 58 patients harboring cavernous malformations (25.9%) were found to have an associated venous malformation (VM). Three (33.3%) of the first 9 patients, in whom the large draining vein of the VM had been left untouched at previous interventions, developed recurrent and/or de novo lesions.

RESULTS:

Histopathological analysis, interestingly, revealed that the new lesions were different in nature (three arteriovenous angiomas in two patients, a capillary telangiectasia in one patient). During extirpation of the new malformation, the draining vein of the VM in these three patients could be coagulated without any adverse events. Coagulation and dissection of the draining vein of the associated VM was performed in six more patients of our series, and this has prevented development of new lesions up to now.

CONCLUSION:

Our results are in favor of the hypothesis that the draining vein of a VM is the actual underlying abnormality of mixed vascular malformations. Causing flow disturbances and having the potential for hemorrhages, the VM seems to promote the development of new adjacent malformations. Thus, permanent cure of associated malformations might depend on the surgical treatment of the VM. We present a preliminary personal series and a thorough review of the literature.

Thrombus and encapsulated hematoma in cerebral cavernous malformations

Thrombi, encapsulated hematomas, and granulation tissue are frequently seen in cerebral cavernous malformations (CCMs). We investigated the role that these histological changes play in repeated hemorrhages in CCMs as well as lesion growth, examining specimens of CCMs surgically harvested from 20 patients. The immunohistochemical study included thrombomodulin (TM) and endothelial cell protein C receptor (EPCR), which are important regulators of blood coagulation. Thick capsules, which contained blood degradation product, were seen in cases with encapsulated hematomas. Clusters of sinusoidal vessels were found outside of these thick capsules. Granulation tissue with inflammatory infiltrates and capillaries was seen in 4 cases with non-capsulated hematomas. Organizing thrombi were seen in sinusoidal vessels in 15 out of 20 cases. Factor VIII-related antigen staining demonstrated numerous capillaries in and around organizing thrombi and within the thickened vessel walls as well as in both the inner and outer sides of the hematoma capsule. TM and EPCR were positive in the endothelial cells of these capillaries, whereas they were negative in those of capillaries in the brain surrounding the lesions. Our study suggests that thrombosed sinusoidal blood vessels could gradually expand by repeated bleeding from numerous capillaries inside the wall and become encapsulated hematomas, and capillaries outside the thickened vessel wall could become sinusoidal blood vessels. Thrombosis within cerebral venules could be one of the causal factors of CCMs.