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Anatomical implications of posterior cephaloceles in the dural venous sinuses

November 2020
Child's Nervous System 36(1)

November 2020
36(1)

DOI:10.1007/s00381-020-04525-6

Authors:

Anderson Alexsander Rodrigues Teixeira

Universidade Federal do Ceará

Daniel Aguiar Dias

Universidade Federal do Ceará

Show all 5 authorsHide

Objective To analyze the venous anatomy of the dural sinuses of patients with posterior encephaloceles, in order to formulate anatomical patterns which can ensure safer surgery.Methods This is a retrospective study, analyzing eight patients diagnosed with posterior encephalocele throughout 1 year.ResultsEight patients with cephaloceles were evaluated in our study from January 2017 to January 2018. The most common alteration was dysgenesis of the straight sinus (n = 7), followed by venous anomalies in the encephalocele and alterations in the SSS (superior sagittal sinus) (n = 4), and the occurrence of a falcine sinus (FC) in 3 patients.Conclusion Anatomical variations are frequent in patients with cephaloceles. Therefore, an understanding of them is necessary for safe and effective treatment.

a Intraoperative image shows the occipital encephalocele. b MRI T2-weighted sagittal image. Shows agenesis of corpus callosum. c Venous phase of angiography in parietal cephalocele (oblique view). The superior sagittal sinus forms a high-positioned confluence

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a Intraoperative image shows occipital encephalocele. b, c Post-contrast CT image (sagittal plane reconstruction) showing concomitant presence of straight sinus and falcine sinus

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a CT of encephalocele. b, c Post-contrast CT image shows bifurcation of superior sagittal sinus

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MRA. a Sagittal MRI T1-W1 sequence with gadolinium contrast. b Sagittal MRI T2-W1. c Coronal MRI T1-W1 sequence with gadolinium contrast. Shows medial occipital encephalocele, with a shallow posterior fossa and reduced volume. Associated with these findings are dysgenesis of the corpus callosum, dilatation of the ventricular system, and hydrocephalus, best visualized in this image by dimensions of the III ventricle. Injection of contrast provided analysis of possible venous content bypassing and enveloping of the hernial sac

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a Posterior view of normal sinus development, in the absence of neural tube defects. b Posterior view of an encephalocele associated with an elevation of the torcular herophili and premature division of the superior sagittal sinus. c Posterior view of the elevated confluence of sinuses, above the encephalocele. d Oblique view of a total division of the superior sagittal sinus associated with an encephalocele. This case resembles the sinus during its embryological development (at the beginning of formation there are bilateral plexuses), showing the non-fusion possibly due to the encephalocele and the adaptation to the neural tube defect

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CASE REPORT

Anatomical implications of posterior cephaloceles in the dural

venous sinuses

Anderson Alexsander Rodrigues Teixeira

&Fernando Furtado de Melo Neto

&Nina Maia Pinheiro de Abreu

Daniel Aguiar Dias

&Moyses Loiola Ponte Souza

Received: 23 October 2019 / Accepted: 25 January 2020

#Springer-Verlag GmbH Germany, part of Springer Nature 2020

Abstract

Objective To analyze the venous anatomy of the dural sinuses of patients with posterior encephaloceles, in order to formulate

anatomical patterns which can ensure safer surgery.

Methods This is a retrospective study, analyzing eight patients diagnosed with posterior encephalocele throughout 1 year.

Results Eight patients with cephaloceles were evaluated in our study from January 2017 to January 2018. The most common

alteration was dysgenesis of the straight sinus (n= 7), followed by venous anomalies in the encephalocele and alterations in the

SSS (superior sagittal sinus) (n= 4), and the occurrence of a falcine sinus (FC) in 3 patients.

Conclusion Anatomical variations are frequent in patients with cephaloceles. Therefore, an understanding of them is necessary

for safe and effective treatment.

Keywords Encephalocele .Nervous system malformations .Dural venous sinuses .Anomalous venous system

Introduction

A cephalocele is the herniation of one or more intracranial

structures through a congenital cranial bone defect or, more

rarely, through normal foramen or fissures in the skull. It can

also be called cranial dysraphism [9,10].

One hypothesis is that both encephalocele and

meningocele develop due to a failure of fusion of the

paraxial mesoderm of the dura mater and the cranium

along the midline, secondary to an adhesion between

the neural and cutaneous ectoderm, before their

disjunction.

The classification of encephaloceles is based on the ana-

tomical location of the skull defect, and the two main groups

are anterior and posterior: anterior encephaloceles are divided

into sincipital (sinciput or forehead) and basal, while posterior

encephaloceles are divided into occipital, occipitocervical,

and parietal [28].

The prevalence of encephaloceles may range from 0.08 to

0.5/1000 live births [1,11,24,27]. Occipital encephaloceles

are more common in the west, while in Asia, frontal or sincip-

ital variations are more prevalent [5,24].

Only 50% of fetuses with encephalocele survive until birth,

with occipital encephaloceles being almost exclusively asso-

ciated with the highest mortality rates [11,13]. Children with

meningocele (a defect that does not contain nervous tissue, but

only the leptomeninges) tend to be neurologically normal

[24], unlike with encephaloceles, which present a higher inci-

dence of seizures and spasticity, and more commonly possess

chromosomal abnormalities (up to 50% of cases). Most have

hydrocephalus and cognitive deficits [5,8,11]. The occipital

variation of these defects is more associated with hydroceph-

alus [7,24](Figs.1,2,and3).

Surgical correction of these defects is important and

diagnostic imaging is required to assess whether struc-

tures that will be reduced or resected contain dural si-

nuses, thus preventing injury or subsequent venous con-

gestion [19]. In light of this, it is necessary to know the

vascular anatomical variations, in order to avoid surgical

complications.

*Anderson Alexsander Rodrigues Teixeira

andersonalexrteixeira@gmail.com

Department of Neurosurgery, Federal University of Ceará - UFC,

Fortaleza, CE, Brazil

Department of Diagnostic Imaging, Federal University of São Paulo -

UNIFESP, São Paulo, SP, Brazil

Department of Diagnostic Imaging, Federal University of Ceará -

UFC, Fortaleza, CE, Brazil

https://doi.org/10.1007/s00381-020-04525-6

/ Published online: 30 January 2020

Child's Nervous System (2020) 36:2857–2862

Content courtesy of Springer Nature, terms of use apply. Rights reserved.

A Topographical Analysis of Encephalocele Locations: Generation of a Standardised Atlas and Cluster Analysis

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CHILD NERV SYST

Objective Encephaloceles are considered to result from defects in the developing skull through which meninges, and potentially brain tissue, herniate. The pathological mechanism underlying this process is incompletely understood. We aimed to describe the location of encephaloceles through the generation of a group atlas to determine whether they occur at random sites or clusters within distinct anatomical regions. Methods Patients diagnosed with cranial encephaloceles or meningoceles were identified from a prospectively maintained database between 1984 and 2021. Images were transformed to atlas space using non-linear registration. The bone defect, encephalocele and herniated brain contents were manually segmented allowing for a 3-dimensional heat map of encephalocele locations to be generated. The centroids of the bone defects were clustered utilising a K-mean clustering machine learning algorithm in which the elbow method was used to identify the optimal number of clusters. Results Of the 124 patients identified, 55 had volumetric imaging in the form of MRI (48/55) or CT (7/55) that could be used for atlas generation. Median encephalocele volume was 14,704 (IQR 3655–86,746) mm³ and the median surface area of the skull defect was 679 (IQR 374–765) mm². Brain herniation into the encephalocele was found in 45% (25/55) with a median volume of 7433 (IQR 3123–14,237) mm³. Application of the elbow method revealed 3 discrete clusters: (1) anterior skull base (22%; 12/55), (2) parieto-occipital junction (45%; 25/55) and (3) peri-torcular (33%; 18/55). Cluster analysis revealed no correlation between the location of the encephalocele with gender (χ² (2, n = 91) = 3.86, p = 0.15). Compared to expected population frequencies, encephaloceles were relatively more common in Black, Asian and Other compared to White ethnicities. A falcine sinus was identified in 51% (28/55) of cases. Falcine sinuses were more common (χ² (2, n = 55) = 6.09, p = 0.05) whilst brain herniation was less common (χ² (2, n = 55) = .16.24, p < 0.0003) in the parieto-occipital location. Conclusion This analysis revealed three predominant clusters for the location of encephaloceles, with the parieto-occipital junction being the most common. The stereotypic location of encephaloceles into anatomically distinct clusters and the coexistence of distinct venous malformations at certain sites suggests that their location is not random and raises the possibility of distinct pathogenic mechanisms unique to each of these regions.

Persistent falcine sinus with temporo-occipital schizencephaly: case report with a review of literature in relation to the undeveloped vein of Galen and/or straight sinus

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CHILD NERV SYST

Falcine sinus is a normal midline embryonic venous sinus present in the fetal brain and usually disappears by birth. Persistent falcine sinus (PFS) has been reported as a normal variant or along with vein of Galen (VOG) malformation, encephalocele, and other abnormalities. Schizencephaly, either closed or open type, has been reported with other associated vascular anomalies. We report a 22-month-old child, who presented with delayed milestones and referred for magnetic resonance (MR) imaging, and the child was found to have PFS with associated bilateral temporo-occipital closed-lip schizencephaly, hippocampal abnormalities, falco-tentorial dehiscence, and white matter abnormalities. The vein of Galen and straight sinus were absent, and the internal cerebral veins were seen draining into superior sagittal sinus via the falcine sinus. These set of abnormalities are unique from abnormalities reported previously in association with the falcine sinus.

A review of extraaxial developmental venous anomalies of the brain involving dural venous flow or sinuses: Persistent embryonic sinuses, sinus pericranii, venous varices or aneurysmal malformations, and enlarged emissary veins

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Neurosurg Focus

This paper is a narrative review of extraaxial developmental venous anomalies (eDVAs) of the brain involving dural venous flow or sinuses: persistent embryonic sinuses, sinus pericranii, enlarged emissary veins, and venous varices or aneurysmal malformations. The article highlights the natural history, anatomy, embryology, imaging, clinical implications, and neurosurgical significance of these lesions, which the authors believe represent a continuum, with different entities characterized by distinct embryopathologic features. The indications and surgical management options are discussed for these individual intracranial pathologies with relevant illustrations, and a novel classification is proposed for persistent falcine sinus (PFS). The role of neurointervention and/or microsurgery in specific cases such as sinus pericranii and enlarged emissary veins of the skull is highlighted. A better understanding of the pathophysiology and developmental anatomy of these lesions can reduce treatment morbidity and mortality. Some patients, including those with vein of Galen malformations (VOGMs), can present with the added systemic morbidity of a high-output cardiac failure. Although VOGM is the most studied and classified of the above-mentioned eDVAs, the authors believe that grouping the former with the other venous anomalies/abnormalities listed above would enable the clinician to convey the exact morphophysiological configuration of these lesions, predict their natural history with respect to evolving venous hypertension or stroke, and extrapolate invaluable insights from VOGM treatment to the treatment of other eDVAs. In recent years, many of these symptomatic venous malformations have been treated with endovascular interventions, although these techniques are still being refined. The authors highlight the broad concept of eDVAs and hope that this work will serve as a basis for future studies investigating the role of evolving focal venous hypertension/global intracranial hypertension and possibilities of fetal surgical intervention in these cases.

Fate of the three embryonic dural sinuses in infants: the primitive tentorial sinus, occipital sinus, and falcine sinus

Article

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Mar 2018
NEURORADIOLOGY

Purpose: The primitive tentorial, occipital, and falcine sinuses are thought to attain the adult pattern or regress between the fetal stage and adulthood. The anatomy of these three primitive dural sinuses has seldom been studied in the infant population, and it remains unclear when these dural sinuses reach the adult condition. Using computed tomography digital subtraction venography (CT-DSV), we analyzed the anatomy of these embryonic dural sinuses in infants. Methods: We included 13 infants who underwent CT-DSV prior to neurosurgery and 35 cases with unruptured cerebral aneurysms as normal adult controls. Three embryonic dural sinuses, i.e., the primitive tentorial, occipital, and falcine sinuses, were retrospectively analyzed in CT-DSV images of infants and adults. We also analyzed the drainage patterns of the superficial middle cerebral vein (SMCV), determined by the connection between the primitive tentorial sinus and the cavernous sinus. Results: The primitive tentorial, occipital, and falcine sinuses were present in 15.4%, 46.2%, and none of the infants, respectively, and in 10.0, 8.6, and 2.9% of the adults, respectively. The difference in SMCV draining pattern between infants and adults was insignificant. The incidence of the occipital sinus was significantly higher in infants than in adults. Conclusions: The connection between the primitive tentorial sinus and the cavernous sinus appears to be established before birth. The occipital sinus is formed at the embryonic stage and mostly regresses after infancy. The falcine sinus is usually obliterated prenatally. Our findings form the basis for interventions by pediatric interventional neuroradiologists and neurosurgeons.

Surgical resection of large encephalocele: a report of two cases and consideration of resectability based on developmental morphology

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Introduction: The first-line treatment of encephalocele is reduction of herniated structures. Large irreducible encephalocele entails resection of the lesion. In such case, it is essential to ascertain preoperatively if the herniated structure encloses critical venous drainage. Case reports: Two cases of encephalocele presenting with large occipital mass underwent magnetic resonance (MR) imaging. In first case, the skin mass enclosed the broad space containing cerebrospinal fluid and a part of occipital lobe and cerebellum. The second case had occipital mass harboring a large portion of cerebrum enclosing dilated ventricular space. Both cases had common venous anomalies such as split superior sagittal sinus and high-positioned torcular herophili. They underwent resection of encephalocele without subsequent venous congestion. We could explain the pattern of venous anomalies in encephalocele based on normal developmental theory. Conclusion: Developmental theory connotes that major dural sinuses cannot herniate into the sac of encephalocele. Irrespective to its size, encephalocele can be resected safely at the neck without subsequent venous congestion.

Venous anomaly analogous to vertical embryonic positioning of the straight sinus associated with atretic cephalocele at the suboccipital region

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Background The coexistence of venous anomalies, such as vertical embryonic positioning of the straight sinus (VEP of SS), has been reported in patients with atretic cephalocele (AC). VEP of SS has been exclusively encountered when the AC is found above the torcular. Clinical presentation We report a patient with suboccipital AC associated with venous anomalies analogous to VEP of SS, consisted of the Galenic venous system which did not drain into the straight sinus in the tentorium, but into the falcine sinus instead. Differences with VEP of SS in our case had no anatomical relationship between the falcine sinus and the suboccipital AC and no large cerebrospinal fluid space around the falcine sinus. A detailed neuroradiological examination was helpful for detecting these minute anomalies.

Parietal atretic cephalocele: Associated cerebral anomalies identified by CT and MR imaging

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We describe a case of atretic cephalocele (AC) characterized by the presence of various cerebral anomalies of different midline structures. In our patient the presence of a parietal AC was associated with an embryonic position of the straight sinus, fenestration of the superior sagittal sinus, an abnormal insertion of the cerebellar tentorium with prominence of the superior cerebellar cistern and a septum pellucidum cyst. These findings, associated with AC, could lead to a worse prognosis with regard to neurodevelopmental milestones. This suggests that even if AC is a benign lesion, a complete evaluation of the brain structures should always be performed in these young patients. © The Author(s) 2015 Reprints and permissions: sagepub.co.uk/journalsPermissions.nav.

Vein of Galen aneurysmal malformations: Critical analysis of the literature with proposal of a new classification system

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Vein of Galen aneurysmal malformations are a rare and diverse group of entities with a complex anatomy, pathophysiology, and serious clinical sequelae. Due to their complexity, there is no uniform treatment paradigm. Furthermore, treatment itself entails the risk of serious complication. Offering the best treatment option is dependent on an understanding of the aberrant anatomy and pathophysiology of these entities, and tailored therapy is recommended. Herein, the authors review the current concepts related to vein of Galen aneurysmal malformations and suggest a new classification system excluding mesodiencephalic plexiform intrinsic arteriovenous malformations from this group of malformations.

Prenatal ultrasonographic detection of regression of an encephalocele.

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Clinical predictors of developmental outcome in patients with cephaloceles: Clinical article

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Nov 2008

Cephaloceles represent primary axial mesodermal defects, occurring in 0.8-4 per 10,000 live births. Prior studies have reported posterior location, hydrocephalus, microcephaly, seizure, and presence of brain tissue as poor prognostic markers for neurological outcome. However, these studies were small and the results were analyzed using univariate tests. The purpose of this study was to investigate the potential risk factors for the occurrence of developmental delay in patients with cephaloceles, using both univariate and multivariable regression techniques. This is a retrospective cohort study of cephalocele cases treated at the Hospital for Sick Children between 1990 and 2006. Two independent investigators collected the data from the Hospital for Sick Children Encephalocele Database and hospital charts. Developmental assessments were made by general pediatricians and neuropsychologists. Both univariate analysis (alpha=0.10) and multivariable logistic regression analysis (alpha=0.05) were performed. Eighty-five cases of cephaloceles were identified. The patient group consisted of 48 boys and 37 girls. Sixty-eight lesions were encephaloceles and 17 were meningoceles. The distribution was as follows: frontal (40 lesions), occipital (33), and parietal (12). Associated conditions included hydrocephalus (23), seizure disorder (17), microcephaly (6), corpus callosal abnormalities (15), heterotopias (9), cerebral dysgenesis (11), and myelomeningocele (1). Evaluation of long-term development revealed that 41 patients (48%) had normal development, 9 (11%) had mild delay, 14 (16%) had moderate delay, and 21 (25%) had severe delay. Hydrocephalus, seizure disorder, microcephaly, presence of associated intracranial abnormalities, and presence of brain tissue were significantly associated with poor outcome on univariate analysis. Multivariable analysis revealed hydrocephalus and presence of intracranial abnormalities to be statistically significant predictors of developmental delay. To the authors' knowledge, this is one of the largest North American cephalocele series documented. Unlike prior studies, location of the cephaloceles is not a significant predictor of outcome. The multivariable regression analysis demonstrates hydrocephalus and the presence of associated intracranial abnormalities as variables with cumulative predictive effects for developmental delay.

The prognosis of occipital encephalocele

Article

Jan 1980

147 cases of occipital cranium bifidum have been followed: 32 had meningoceles and 115 encephaloceles. Females predominated (69%). 90% of the meningocele and 43% of the encephalocele patients survived. Of the former 48% are normal and 16% are both physically and mentally handicapped. Of the latter only 4% are normal and 26% are physically and mentally handicapped. Cerebral tissue in the sac and associated microcephaly are bad prognostic features.

Anatomical implications of posterior cephaloceles in the dural venous sinuses

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