Not Dandy Walker variant: a review of prominent retrocerebellar CSF space in children

The prominent retrocerebellar cerebrospinal fluid (CSF) space can be frequently encountered on paediatric neuroimaging studies. In cases involving abnormal vermian development where imaging does not align with the established criteria of Dandy-Walker malformation (DWM), the term "Dandy-Walker variant or continuum" has been historically employed to describe the aberrant posterior fossa development. Instead, the emphasis is on a more elaborate description of the findings in the posterior fossa. Moreover, combining the findings in the supratentorial brain can occasionally predict certain neurogenetic disorders that mimic Dandy-Walker phenotype. The present review demonstrates and differentiates the imaging features of various entities that result in an enlarged retrocerebellar CSF space, such as inferior vermian hypoplasia (IVH) and several neurogenetic conditions.

Fetal and neonatal outcomes of posterior fossa anomalies: a retrospective cohort study

The primary aim of this study was to estimate the incidence of posterior fossa anomalies (PFA) and assess the associated outcomes in King Abdulaziz Medical City (KAMC), Riyadh. All fetuses diagnosed by prenatal ultrasound with PFA from 2017 to 2021 in KAMC were analyzed retrospectively. PFA included Dandy-Walker malformation (DWM), mega cisterna magna (MCM), Blake's pouch cyst (BPC), and isolated vermian hypoplasia (VH). The 65 cases of PFA were 41.5% DWM, 46.2% MCM, 10.8% VH, and 1.5% BPC. The annual incidence rates were 2.48, 2.64, 4.41, 8.75, and 1.71 per 1000 anatomy scans for 2017, 2018, 2019, 2020, and 2021, respectively. Infants with DWM appeared to have a higher proportion of associated central nervous system (CNS) abnormalities (70.4% vs. 39.5%; p-value = 0.014) and seizures than others (45% vs. 17.9%; p-value = 0.041). Ten patients with abnormal genetic testing showed a single gene mutation causing CNS abnormalities, including a pathogenic variant in MPL, C5orf42, ISPD, PDHA1, PNPLA8, JAM3, COL18A1, and a variant of uncertain significance in the PNPLA8 gene. Our result showed that the most common PFA is DWM and MCM. The autosomal recessive pathogenic mutation is the major cause of genetic disease in Saudi patients diagnosed with PFA.

Meckel-Gruber syndrome together with Dandy-Walker malformation: an atypical case report of a 2nd recurrence in a consanguine marriage

Meckel-Gruber syndrome is a lethal disorder characterized by occipital encephalocele, polycystic kidneys, and polydactyly. In most cases, it is identified and terminated antenatally. In this report, the authors present a case of Meckel-Gruber syndrome together with Dandy-Walker malformation. A pregnant woman referred at the 28th week of gestation with an abnormal ultrasound scan showing posterior encephalocele and bilaterally enlarged kidneys. Further imaging also indicated communication between the 4th ventricle and posterior cerebellar cerebrospinal fluid space, after which the fetus was diagnosed with Meckel-Gruber syndrome and Dandy-Walker malformation. Pregnancy termination was refused by the parents and the offspring was prematurely born to be the 2nd recurrence of Meckel-Gruber syndrome in this consanguine family. Remarkably, at the 3 different pregnancies, ultrasound was inconclusive before the 7th month of gestation. Though up to date Meckel-Gruber syndrome is ultimately lethal, the lifespan of affected newborns varied greatly. We suggest developing a severity classification to estimate life expectancy in unterminated cases.

PHACE syndrome: not always 'tilting telephones' and Dandy-Walker malformations…

Linked article: This Editorial comments on Pomar et al. Click here to view the article.

Dandy-Walker Phenotype with Brainstem Involvement: 2 Distinct Subgroups with Different Prognosis

BACKGROUND AND PURPOSE

Although cardinal imaging features for the diagnostic criteria of the Dandy-Walker phenotype have been recently defined, there is a large range of unreported malformations among these patients. The brainstem, in particular, deserves careful attention because malformations in this region have potentially important implications for clinical outcomes. In this article, we offer detailed information on the association of brainstem dysgenesis in a large, multicentric cohort of patients with the Dandy-Walker phenotype, defining different subtypes of involvement and their potential clinical impact.

MATERIALS AND METHODS

In this established multicenter cohort of 329 patients with the Dandy-Walker phenotype, we include and retrospectively review the MR imaging studies and clinical records of 73 subjects with additional brainstem malformations. Detailed evaluation of the different patterns of brainstem involvement and their potential clinical implications, along with comparisons between posterior fossa measurements for the diagnosis of the Dandy-Walker phenotype, was performed among the different subgroups of patients with brainstem involvement.

RESULTS

There were 2 major forms of brainstem involvement in patients with Dandy-Walker phenotype including the following: 1) the mild form with anteroposterior disproportions of the brainstem structures "only" (57/73; 78%), most frequently with pontine hypoplasia (44/57; 77%), and 2) the severe form with patients with tegmental dysplasia with folding, bumps, and/or clefts (16/73; 22%). Patients with severe forms of brainstem malformation had significantly increased rates of massive ventriculomegaly, additional malformations involving the corpus callosum and gray matter, and interhemispheric cysts. Clinically, patients with the severe form had significantly increased rates of bulbar dysfunction, seizures, and mortality.

CONCLUSIONS

Additional brainstem malformations in patients with the Dandy-Walker phenotype can be divided into 2 major subgroups: mild and severe. The severe form, though less prevalent, has characteristic imaging features, including tegmental folding, bumps, and clefts, and is directly associated with a more severe clinical presentation and increased mortality.

The Management of Hydrocephalus in Midline Posterior Fossa Cystic Collections: Surgical Outcome From a Retrospective Single-Center Case Series of 54 Consecutive Pediatric Patients

BACKGROUND

Hydrocephalus frequently occurs with midline posterior fossa cystic collections. The classification of this heterogeneous group of developmental anomalies, including Dandy-Walker malformation, persisting Blake's pouch, retrocerebellar arachnoid cysts, and mega cisterna magna, is subject of debate. The absence of diagnostic criteria is confusing regarding the ideal management of PFCC-related hydrocephalus.

OBJECTIVE

To decipher the surgical strategy for the treatment of children with PFCC-related hydrocephalus through a retrospective analysis of the surgical outcome driven by their clinical and radiological presentation.

METHODS

This study enrolled patients operated of symptomatic PFCC-related hydrocephalus. Clinical and MRI features were examined, as well as the surgical outcome. Unbiased subgroup classification of the patients was performed with multiple component analysis as a function of imaging characteristics and hierarchical clustering on principal component. Outcome was assessed with binomial logistic regression and Kaplan-Meier analysis.

RESULTS

Fifty-four patients were included between 2007 and 2021. Multiple component analysis suggested that cerebellar and vermian hypoplasia, vermian rotation, basal-tentorial angle, and fastigial angle were strongly correlated. Hierarchical clustering and the distribution of the patients in the bidimensional plot showed the clear segregation of 3 major clusters, which correlated with the radiological diagnosis ( P < .01). Binomial logistic regression and survival analysis showed that endoscopic third ventriculostomy was an effective treatment for patients with persisting Blake's pouch, while failing to control hydrocephalus in most of patients with Dandy-Walker malformation.

CONCLUSION

Preoperative MRI in patients with PFCC-related hydrocephalus is essential to better define the diagnosis. The choice of treatment strategy notably relies on correct radiological diagnosis.

Refining the Neuroimaging Definition of the Dandy-Walker Phenotype

BACKGROUND AND PURPOSE

The traditionally described Dandy-Walker malformation comprises a range of cerebellar and posterior fossa abnormalities with variable clinical severity. We aimed to establish updated imaging criteria for Dandy-Walker malformation on the basis of cerebellar development.

MATERIALS AND METHODS

In this multicenter study, retrospective MR imaging examinations from fetuses and children previously diagnosed with Dandy-Walker malformation or vermian hypoplasia were re-evaluated, using the choroid plexus/tela choroidea location and the fastigial recess shape to differentiate Dandy-Walker malformation from vermian hypoplasia. Multiple additional measures of the posterior fossa and cerebellum were also obtained and compared between Dandy-Walker malformation and other diagnoses.

RESULTS

Four hundred forty-six examinations were analyzed (174 fetal and 272 postnatal). The most common diagnoses were Dandy-Walker malformation (78%), vermian hypoplasia (14%), vermian hypoplasia with Blake pouch cyst (9%), and Blake pouch cyst (4%). Most measures were significant differentiators of Dandy-Walker malformation from non-Dandy-Walker malformation both pre- and postnatally (P < .01); the tegmentovermian and fastigial recess angles were the most significant quantitative measures. Posterior fossa perimeter and vascular injury evidence were not significant differentiators pre- or postnatally (P > .3). The superior posterior fossa angle, torcular location, and vermian height differentiated groups postnatally (P < .01), but not prenatally (P > .07).

CONCLUSIONS

As confirmed by objective measures, the modern Dandy-Walker malformation phenotype is best defined by inferior predominant vermian hypoplasia, an enlarged tegmentovermian angle, inferolateral displacement of the tela choroidea/choroid plexus, an obtuse fastigial recess, and an unpaired caudal lobule. Posterior fossa size and torcular location should be eliminated from the diagnostic criteria. This refined phenotype may help guide future study of the numerous etiologies and varied clinical outcomes.

Regional brain development in fetuses with Dandy-Walker malformation: A volumetric fetal brain magnetic resonance imaging study

Dandy-Walker malformation (DWM) is a common prenatally diagnosed cerebellar malformation, characterized by cystic dilatation of the fourth ventricle, upward rotation of the hypoplastic vermis, and posterior fossa enlargement with torcular elevation. DWM is associated with a broad spectrum of neurodevelopmental abnormalities such as cognitive, motor, and behavioral impairments, which cannot be explained solely by cerebellar malformations. Notably, the pathogenesis of these symptoms remains poorly understood. This study investigated whether fetal structural developmental abnormalities in DWM extended beyond the posterior fossa to the cerebrum even in fetuses without apparent cerebral anomalies. Post-acquisition volumetric fetal magnetic resonance imaging (MRI) analysis was performed in 12 fetuses with DWM and 14 control fetuses. Growth trajectories of the volumes of the cortical plate, subcortical parenchyma, cerebellar hemispheres, and vermis between 18 and 33 weeks of gestation were compared. The median (interquartile range) gestational ages at the time of MRI were 22.4 (19.4–24.0) and 23.9 (20.6–29.2) weeks in the DWM and control groups, respectively (p = 0.269). Eight of the 12 fetuses with DWM presented with associated cerebral anomalies, including hydrocephalus (n = 3), cerebral ventriculomegaly (n = 3), and complete (n = 2) and partial (n = 2) agenesis of the corpus callosum (ACC); 7 presented with extracerebral abnormalities. Chromosomal abnormalities were detected by microarray analysis in 4 of 11 fetuses with DWM, using amniocentesis. Volumetric analysis revealed that the cortical plate was significantly larger in fetuses with DWM than in controls (p = 0.040). Even without ACC, the subcortical parenchyma, whole cerebrum, cerebellar hemispheres, and whole brain were significantly larger in fetuses with DWM (n = 8) than in controls (p = 0.004, 0.025, 0.033, and 0.026, respectively). In conclusion, volumetric fetal MRI analysis demonstrated that the development of DWM extends throughout the brain during the fetal period, even without apparent cerebral anomalies.

Position of the choroid plexus of the fourth ventricle in first- and second-trimester fetuses: a novel approach to early diagnosis of cystic posterior fossa anomalies

OBJECTIVE

To describe the sonographic appearance and position of the choroid plexus of the fourth ventricle (4V-CP) between 12 and 21 weeks' gestation in normal fetuses and in fetuses with Dandy-Walker malformation (DWM) or Blake's pouch cyst (BPC).

METHODS

The study population comprised 90 prospectively recruited normal singleton pregnancies and 41 pregnancies identified retrospectively from our institutional database that had a suspected posterior fossa anomaly at 12-13 weeks' gestation based on the ultrasound finding of abnormal hindbrain spaces. In all cases the final diagnosis was confirmed by prenatal and/or postnatal magnetic resonance imaging or postmortem examination. All pregnancies underwent a detailed ultrasound assessment, including a dedicated examination of the posterior fossa, at 12-13 weeks, 15-16 weeks and 20-21 weeks of gestation. Two-dimensional ultrasound images of the midsagittal and coronal views of the brain through the posterior fontanelle and three-dimensional volume datasets were obtained. Multiplanar orthogonal image correlation with volume contrast imaging was used as the reference visualization mode. Two independent operators, blinded to the fetal outcome, were asked to classify the 4V-CP as visible or not visible in both normal and abnormal cases, and to assess if the 4V-CP was positioned inside or outside the cyst in fetuses with DWM and BPC.

RESULTS

Of the 41 fetuses with apparently isolated cystic posterior fossa anomaly in the first trimester, eight were diagnosed with DWM, 29 were diagnosed with BPC and four were found to be normal in the second trimester. The position of the 4V-CP differed between DWM, BPC and normal cases in the first- and second-trimester ultrasound examinations. In particular, in normal fetuses, no cyst was present and, in the midsagittal and coronal planes of the posterior fossa, the 4V-CP appeared as an echogenic oval-shaped structure located inside the 4V apparently attached to the cerebellar vermis. In fetuses with DWM, the 4V-CP was not visible in the midsagittal view because it was displaced inferolaterally by the cyst. In contrast, in the coronal view of the posterior brain, the 4V-CP was visualized in all cases with DWM at 12-13 weeks, with a moderate decrease in the visualization rate at 15-16 weeks (87.5%) and at 20-21 weeks (75%). In the coronal view, the 4V-CP was classified as being outside the cyst in all DWM cases at 12-13 weeks and in 87.5% and 75% of cases at 15-16 and 20-21 weeks, respectively. In fetuses with BPC, the 4V-CP was visualized in all cases in both the midsagittal and coronal views at 12-13 weeks and in 100% and 96.6% of cases, respectively, at 15-16 weeks. In the coronal view, the 4V-CP was classified as being inside the cyst in 28 (96.6%), 27 (93.1%) and 25 (86.2%) cases at 12-13, 15-16 and 20-21 weeks, respectively. The medial segment of the 4V-CP was visualized near the inferior part of the vermis.

CONCLUSIONS

Our study shows that longitudinal ultrasound assessment of the 4V-CP and its temporal changes from 12 to 21 weeks is feasible. The 4V-CP is located inside the cyst, just below the vermis, in BPC and outside the cyst, inferolaterally displaced and distant from the vermian margin, in DWM, consistent with the pathogenesis of the two conditions. The position of the 4V-CP is a useful sonographic marker that can help differentiate between DWM and BPC as early as in the first trimester of pregnancy. © 2021 International Society of Ultrasound in Obstetrics and Gynecology.

An incidental finding of Dandy-Walker malformation

ABSTRACT

Dandy-Walker malformation is a rare congenital anomaly affecting the posterior fossa, occurring in one in 30,000 births. Its hallmark characteristics include hypoplasia of the vermis, dilation of the fourth ventricle, and an enlarged posterior fossa. This case study describes a finding of Dandy-Walker malformation during a workup of encephalopathy in a patient on veno-venous extracorporeal membrane oxygenation for acute respiratory distress syndrome.

Clinical Follow-Up of Patients with Neurocutaneous Melanosis in a Tertiary Center; Proposed Modification in Diagnostic Criteria

INTRODUCTION

Neurocutaneous melanosis (NCM) is a rare congenital syndrome. Except for some retrospective studies, information on clinical follow-up and management of these patients are limited. This study aimed to review our experience on diagnostic protocol and clinical follow-up of patients with NCM in a referral children's hospital in Iran.

METHODS

Between 2012 and 2019, eight patients with NCM were consecutively managed in our center. Brain magnetic resonance imaging and cutaneous biopsy were done in all patients at diagnosis. Follow-up surveillance and characteristics of the disease are described.

RESULTS

The mean follow-up period was 25.75 ± 13.81 months, and 75% of patients were male. Most magnetic resonance imaging findings were hypersignal lesions in the temporal lobe (75%), cerebellum (62.5%), brainstem (50%), and thalamus (12.5%). Dandy-Walker syndrome was found in 4 patients (50%), and shunt-dependent hydrocephalus was found in 3 patients (37.5%). Cutaneous malignant melanoma and malignant involvement of the central nervous system were found in 2 (25%) and 3 cases (37.5%), respectively. The mortality rate was 37.5%.

CONCLUSIONS

There are no specific guidelines for management of NCM due to the rarity of the disease. This study proposed modifications in diagnostic criteria, as well as recommendations for follow-up surveillance.

Quantitative fetal magnetic resonance imaging assessment of cystic posterior fossa malformations

OBJECTIVE

Normal cognitive development usually requires a structurally intact and complete cerebellar vermis. The aim of this study was to evaluate whether quantification by fetal magnetic resonance imaging (MRI) of vermis- and brainstem-specific imaging markers improves the definition of cystic posterior fossa malformations (cPFM).

METHODS

Fetuses diagnosed with cPFM that had an available midsagittal plane on T2-weighted MRI were identified retrospectively and compared with gestational-age (GA) matched brain-normal controls. Fetuses with cPFM were assigned to three groups, according to standard criteria (vermian size and brainstem-vermis (BV) angle): normal vermian area and BV angle < 25° (Group 1); reduced vermian area and/or BV angle of 25-45° (Group 2); and reduced vermian area and BV angle > 45° (Group 3; Dandy-Walker malformation (DWM) group). The number of differentiable vermian lobules and the areas of the vermis, mesencephalon, pons and medulla oblongata were quantified, correlated with and controlled for GA, and compared between the study groups.

RESULTS

In total, 142 cases of cPFM were included, with a mean GA of 25.20 ± 5.11 weeks. Cases comprised Blake's pouch cyst (n = 46), arachnoid cyst (n = 12), inferior vermian hypoplasia (n = 5), megacisterna magna (n = 35) and classic DWM (n = 44). In the control group, 148 fetuses were included, with a mean GA of 25.26 ± 4.12 weeks. All quantified areas and the number of differentiable vermian lobules had a significant positive correlation with GA. The number of vermian lobules and the areas of all quantified regions, except for that of the medulla oblongata, differed significantly between the study groups (P ≤ 0.015 for all). The control group had the highest number of differentiable vermian lobules and the DWM group had the lowest (P < 0.01).

CONCLUSIONS

Prenatal MRI assessment of vermian lobules is a useful addition to standard neuroradiological and neurosonographic techniques. The quantification of vermian lobules using fetal MRI allows further differentiation of cPFM into subgroups and thereby improves the classification of hindbrain malformations. © 2019 The Authors. Ultrasound in Obstetrics & Gynecology published by John Wiley & Sons Ltd on behalf of the International Society of Ultrasound in Obstetrics and Gynecology.

Prenatal sonographic diagnosis of Dandy-Walker malformation and type III lissencephaly: A novel association

Dandy-Walker malformation (DWM) may occur as part of Mendelian disorders such as Walker-Warburg and Meckel-Gruber syndromes. We report a novel association with type III lissencephaly in a 22-week male fetus. Ultrasound showed fetal akinesia deformation sequence, single umbilical artery, microlissencephaly, hydranencephaly with cerebral lamination, DWM, and pontocerebellar hypoplasia. These abnormalities were confirmed by magnetic resonance imaging and autopsy, which also revealed pulmonary and adrenal hypoplasia, common mesentery and bilateral uretero-pyelo-calyceal dilatation. Neuropathological examination showed brain calcifications and diffuse neuronal degeneration. We conclude that DWM may be a feature of type III lissencephaly and that this association can be easily diagnosed by ultrasound.

The Fetal Posterior Fossa on Prenatal Ultrasound Imaging: Normal Longitudinal Development and Posterior Fossa Anomalies

Fetal neurosonography and the assessment of the posterior fossa have gained in importance during the last 2 decades primarily due to the development of high-resolution ultrasound probes and the introduction of 3 D sonography. The anatomical development of the posterior fossa can be visualized well with the newest ultrasound technologies. This allows better knowledge of the anatomical structures and helps with understanding of the development of malformations of the posterior fossa. In this article the longitudinal development of the posterior fossa structures will be reviewed. The embryologic description will be compared with ultrasound descriptions. These embryologic and anatomic illustrations form the basis for the screening and diagnosis of malformations of the posterior fossa. During the first trimester, screening for open spina bifida as well as cystic malformations of the posterior fossa is possible. In the second and third trimester, malformations of the posterior fossa can be subdivided into 3 groups: fluid accumulation in the posterior fossa (Dandy-Walker malformation, Blake's pouch cyst, mega cisterna magna, arachnoid cyst, vermian hypoplasia), decreased cerebellar biometrics (volume) (cerebellar hypoplasia, pontocerebellar hypoplasia) and suspicious cerebellar anatomy (Arnold-Chiari malformation, rhombencephalosynapsis, Joubert syndrome). This algorithm, in combination with knowledge of normal development, facilitates the diagnostic workup of malformations of the posterior fossa.

Hindbrain morphometry and choroid plexus position in differential diagnosis of posterior fossa cystic malformations

OBJECTIVE

To assess the differential diagnostic significance of a series of quantitative and qualitative variables of the cerebellar vermis in fetuses with posterior fossa cystic malformation, including Dandy-Walker malformation (DWM), vermian hypoplasia (VH) and Blake's pouch cyst (BPC).

METHODS

This was a retrospective study of confirmed cases of DWM, VH and BPC, diagnosed at the Fetal Medicine and Surgery Unit of the Federico II University between January 2005 and June 2013 or the Fetal Medicine and Surgery Unit of G. Gaslini Hospital between July 2013 and September 2017. All included cases had good-quality three-dimensional (3D) volume datasets of the posterior fossa, acquired by transvaginal ultrasound through the posterior fontanelle. The midsagittal view of the posterior fossa was the reference view for the study. We assessed brainstem-tentorium angle and brainstem-vermis angle (BVA), as well as craniocaudal (CCVD) and anteroposterior (APVD) vermian diameters and vermian area (VA), which were normalized by biparietal diameter (BPD) to take into account gestational age (CCVD/BPD × 100, APVD/BPD × 100 and VA/BPD × 100, respectively). Finally, the position of the fourth ventricular choroid plexus (4VCP) was defined as normal ('up') or abnormal ('down'), relative to the roof/cyst inlet of the fourth ventricle.

RESULTS

We analyzed 67 fetuses with posterior fossa malformations (24 cases of DWM, 13 of VH and 30 of BPC). The mean gestational age at diagnosis was 23.6 weeks. Regardless of gestational age, the BVA differed significantly between the three groups, and the VA/BPD was able to differentiate between VH and BPC. In differentiating between VH and BPC, the greatest areas under the receiver-operating characteristics curve were those for VA/BPD ratio. The 4VCP position was down in all cases of DWM and VH, while it was up in all cases of BPC.

CONCLUSIONS

Our data support the concept that VA/BPD ratio and 4VCP position may be used to differentiate between DWM, VH and BPC in the fetus. In our series, the position of the 4VCP had the highest accuracy, but a larger number of VH cases should be evaluated to confirm that an up position of the 4VCP indicates BPC while a down position indicates DWM or VH. Copyright © 2018 ISUOG. Published by John Wiley & Sons Ltd.

Long Survival of a Patient with Trisomy 18 and Dandy-Walker Syndrome

Trisomy 18 is a genetic disease resulting from an extra chromosome 18, characterized by a broad clinical spectrum, poor prognosis and low rates of survival. This is the case of a 12 year-old girl diagnosed with full trisomy 18, and multiple malformations, including Dandy-Walker Syndrome and congenital heart defects on long term survival. At nine months, a new echocardiogram showed a double outlet right ventricle, significant pulmonary stenosis, patent ductus arteriosus and ventricular septal defect. Cardiac surgery was performed at one year and seven months. Early surgical intervention and multidisciplinary follow-up may change the clinical outcome of the disease. Further studies are required to evaluate the benefit of invasive procedures such as cardiac surgery on survival of patients with trisomy 18.

Prenatal diagnosis of cervical ribs by three-dimensional ultrasound in a foetus with a herniated Dandy-Walker cyst

We present a case report of a foetus with a herniated Dandy-Walker cyst and bilateral rudimentary cervical ribs. The cervical ribs were visualised prenatally by three-dimensional ultrasound and confirmed by post-termination radiography. The prevalence of cervical ribs is higher in deceased fetuses and neonates with or without structural abnormalities compared with healthy individuals and might be regarded as a marker of disadvantageous fetal development. We demonstrate that evaluation of the fetal vertebral pattern by three-dimensional ultrasonography, including the cervical region, is feasible and could provide valuable information regarding fetal and neonatal prognosis.

Dandy-Walker syndrome with duplex kidney abnormalities in trisomy 18 - A rare case report

OBJECTIVE

Trisomy 18 is one of the major numerical chromosomal disorders. The incidence of trisomy 18 is approximately one in 6000 live births. Dandy-Walker malformation (DWM) is the most common congenital malformation of the cerebellum, with an incidence of about one in 5000 live births. The incidence of trisomy 18 associated with DWM is rare and long-term survival rate is very low.

CASE REPORT

A case involving a 39-year-old pregnant female with a case of trisomy 18 associated with DWM.

CONCLUSION

The incidence of trisomy 18 associated with DWM is rare, and our report presents an unusual case that supplements our knowledge of this condition. We report a case involving a 39-year-old pregnant female with a case of trisomy 18 associated with Dandy-Walker malformation (DWM). Fetal ultrasonography showed hypoplasia of the cerebellar vermis and dilatation of the fourth ventricle and was characterized by an enlarged posterior fossa. Fetal magnetic resonance imaging showed inferior vermian hypoplasia and a large posterior fossa cyst communicating with the fourth ventricle causing high insertion of the torcular herophili, which was compatible with DWM. Furthermore, the karyotyping report revealed trisomy 18. The incidence of trisomy 18 associated with DWM is rare, and our report presents an unusual case that supplements our knowledge of this condition.

Prenatal diagnosis of Joubert syndrome: A case report and literature review

INTRODUCTION

Joubert syndrome (JS) is a rare autosomal recessive inherited disease belonging to ciliopathy with the causative mutation of genes. Except for X-linked inheritance, the high recurrence rate of a family is about 25%. After birth, it may cause a series of neurological symptoms, even with retina, kidney, liver, and other organ abnormalities, which is defined as Joubert syndrome and related disorders (JSRD). Molecular genetics research contributes to disease prediction and genetic counseling. Prenatal diagnosis is rare. Magnetic resonance imaging (MRI) is usually the first-choice diagnostic modality with typical brain images characterized by the molar tooth sign. We describe a case of JS prenatally and Dandy-Walker malformation for the differential diagnosis based on ultrasonograms. We also review the etiology, imaging features, clinical symptoms, and diagnosis of JSRD.

CASE PRESENTATION

A 22-year-old woman was pregnant at 27 1/7 weeks' gestation with fetal cerebellar vermis hypoplasia. Fetal ultrasonography and MRI confirmed a diagnosis of JS at our center. The couple finally opted to terminate the fetus, which had a normal appearance and growth parameters. The couple also had an AHI1 gene mutation on chromosome 6.

CONCLUSIONS

Currently, a diagnosis of JS is commonly made after birth. Fewer cases of prenatal diagnosis by ultrasonography have been made, and they are more liable to be misdirected because of some nonspecial features that also manifest in Dandy-Walker malformation, cranio-cerebello-cardiac syndrome, and so on.

[Dandy-Walker variant: Case report]

INTRODUCTION

Dandy Walker variant is defined by a variable hypoplasia of the cerebellar vermix with or without posterior fossa increase and without tentorium elevation.

OBJECTIVE

describe the case of a rare disease and emphasise the need to clarify the aetiology of prenatal malformations, as well as its multidisciplinary management.

CASE REPORT

A male patient, 8 years of age, with a history of Infantile Cerebral Palsy and epilepsy, who was admitted with a history of tonic-clonic seizures. He was admitted due to psycho-motor developmental delay. During his hospitalisation, he had multiple seizure episodes, controlled with anticonvulsants. A computerized tomography was performed, in which communication was observed between the cisterna magna and fourth ventricle (the latter increased in size). In addition, the cerebellar vermix showed a partial hypoplasia. All these findings were compatible with a variant of the Dandy Walker syndrome.

CONCLUSION

Dandy Walker variant may be asymptomatic and the images found may not indicate them as the cause of developmental disorders, due to its association with multiple syndromes and chromosomal abnormalities. Clinical presentation and prognosis depends on the related disorders, and a multidisciplinary approach is important, because the treatment depends on the symptoms presented.

Systematic review and meta-analysis of isolated posterior fossa malformations on prenatal ultrasound imaging (part 1): nomenclature, diagnostic accuracy and associated anomalies

OBJECTIVE

To explore the outcome in fetuses with prenatal diagnosis of posterior fossa anomalies apparently isolated on ultrasound imaging.

METHODS

MEDLINE and EMBASE were searched electronically utilizing combinations of relevant medical subject headings for 'posterior fossa' and 'outcome'. The posterior fossa anomalies analyzed were Dandy-Walker malformation (DWM), mega cisterna magna (MCM), Blake's pouch cyst (BPC) and vermian hypoplasia (VH). The outcomes observed were rate of chromosomal abnormalities, additional anomalies detected at prenatal magnetic resonance imaging (MRI), additional anomalies detected at postnatal imaging and concordance between prenatal and postnatal diagnoses. Only isolated cases of posterior fossa anomalies - defined as having no cerebral or extracerebral additional anomalies detected on ultrasound examination - were included in the analysis. Quality assessment of the included studies was performed using the Newcastle-Ottawa Scale for cohort studies. We used meta-analyses of proportions to combine data and fixed- or random-effects models according to the heterogeneity of the results.

RESULTS

Twenty-two studies including 531 fetuses with posterior fossa anomalies were included in this systematic review. The prevalence of chromosomal abnormalities in fetuses with isolated DWM was 16.3% (95% CI, 8.7-25.7%). The prevalence of additional central nervous system (CNS) abnormalities that were missed at ultrasound examination and detected only at prenatal MRI was 13.7% (95% CI, 0.2-42.6%), and the prevalence of additional CNS anomalies that were missed at prenatal imaging and detected only after birth was 18.2% (95% CI, 6.2-34.6%). Prenatal diagnosis was not confirmed after birth in 28.2% (95% CI, 8.5-53.9%) of cases. MCM was not significantly associated with additional anomalies detected at prenatal MRI or detected after birth. Prenatal diagnosis was not confirmed postnatally in 7.1% (95% CI, 2.3-14.5%) of cases. The rate of chromosomal anomalies in fetuses with isolated BPC was 5.2% (95% CI, 0.9-12.7%) and there was no associated CNS anomaly detected at prenatal MRI or only after birth. Prenatal diagnosis of BPC was not confirmed after birth in 9.8% (95% CI, 2.9-20.1%) of cases. The rate of chromosomal anomalies in fetuses with isolated VH was 6.5% (95% CI, 0.8-17.1%) and there were no additional anomalies detected at prenatal MRI (0% (95% CI, 0.0-45.9%)). The proportions of cerebral anomalies detected only after birth was 14.2% (95% CI, 2.9-31.9%). Prenatal diagnosis was not confirmed after birth in 32.4% (95% CI, 18.3-48.4%) of cases.

CONCLUSIONS

DWM apparently isolated on ultrasound imaging is a condition with a high risk for chromosomal and associated structural anomalies. Isolated MCM and BPC have a low risk for aneuploidy or associated structural anomalies. The small number of cases with isolated VH prevents robust conclusions regarding their management from being drawn. Copyright © 2015 ISUOG. Published by John Wiley & Sons Ltd.

Appearance of fetal posterior fossa at 11-14 weeks in fetuses with Dandy-Walker malformation or chromosomal anomalies

OBJECTIVE

To describe the sonographic appearance of fetal posterior fossa anatomy at 11-14 weeks of pregnancy and to assess the outcome of fetuses with increased intracranial translucency (IT) and/or brainstem-to-occipital bone (BSOB) diameter.

METHODS

Reference ranges for brainstem (BS), IT and cisterna magna (CM) measurements, BSOB diameter and the BS : BSOB ratio were obtained from the first-trimester ultrasound examination of 233 fetuses with normal postnatal outcome (control group). The intraobserver and interobserver variability of measurements were investigated using 73 stored ultrasound images. In addition, a study group of 17 fetuses with increased IT and/or BSOB diameter was selected to assess outcome.

RESULTS

No significant intraobserver or interobserver variability was found for any measurement in the control group. In the study group, IT was increased in all cases and BSOB diameter was above the 95(th) centile of the calculated normal range in all but two (88%) cases. In 13/17 study cases, only two of the three posterior brain spaces were recognized on ultrasound. These 13 fetuses had a larger BSOB diameter than did the four cases that showed all three posterior brain spaces, and had severe associated anomalies including Dandy-Walker malformation (DWM) and/or chromosomal anomalies.

CONCLUSIONS

Visualization of the fetal posterior fossa anatomy at 11-14 weeks' gestation is feasible. Increased fluid in the posterior brain at 11-14 weeks, particularly in the case of non-visibility of the septation that divides the future fourth ventricle from the CM, is an important risk factor for cystic posterior fossa malformations, in particular DWM, and/or chromosomal aberrations. Copyright © 2015 ISUOG. Published by John Wiley & Sons Ltd.

[Megacisterna magna as incidental finding in a boy with ADHD]

In this case report we describe how a 13-year-old boy with a complex development profile was diagnosed with adhd and who was also found to have a megacisterna magna, a posterior fossa anomaly in the Dandy-Walker continuum. We searched the literature for reports of other patients who had this (mild) brain anomaly along with psychiatric problems in general and attention problems in particular. Our search of the literature suggested a possible link between the two diagnostic entities.

Assessment of fetal midbrain and hindbrain in mid-sagittal cranial plane by three-dimensional multiplanar sonography. Part 2: application of nomograms to fetuses with posterior fossa malformations

OBJECTIVES

To apply fetal midbrain (MB) and hindbrain (HB) nomograms, developed using three-dimensional multiplanar sonographic reconstruction (3D-MPR) in the mid-sagittal cranial plane, to fetuses with known posterior fossa malformations.

METHODS

In this retrospective study we examined sonographic volumes obtained by sagittal acquisition in 43 fetuses diagnosed with posterior fossa abnormalities and evaluated in the mid-sagittal cranial plane, using 3D-MPR, the following: MB parameters tectal length (TL) and anteroposterior midbrain diameter (APMD), and HB parameters anteroposterior pons diameter (APPD), superoinferior vermian diameter (SIVD) and anteroposterior vermian diameter (APVD). Fetuses were grouped, according to malformation, into eight categories: cobblestone malformation complex (CMC, n = 3), Chiari-II malformation (C-II, n = 7), pontocerebellar hypoplasia (PCH, n = 2), rhombencephalosynapsis (RES, n = 4), Dandy-Walker malformation (n = 8), vermian dysgenesis (VD, n = 7), persistent Blake's pouch cyst (n = 6) and megacisterna magna (n = 6). In each case and for each subgroup, the MB-HB biometric parameters and their z-scores were evaluated with reference to our new nomograms.

RESULTS

The new MB-HB nomograms were able to identify the brainstem and vermian anomalies and differentiate fetuses with MB-HB malformations from those with isolated enlarged posterior fossa cerebrospinal fluid spaces. Use of the nomograms enabled detection of an elongated tectum in fetuses with CMC, C-II and RES, and a flattened pontine belly in cases of CMC, PCH and VD. In the fetuses with VD, the nomograms enabled division into three distinctive groups: (1) those with small SIVD and APVD, (2) those with normal SIVD but small APVD, and (3) those with small SIVD but normal APVD.

CONCLUSIONS

Application of our new reference data, that for the first time include the MB, enables accurate diagnosis of brain malformations affecting the MB and HB and makes possible novel characterization of previously described features of posterior fossa anomalies.

Open fourth ventricle prior to 20 weeks' gestation: a benign finding?

OBJECTIVE

To evaluate the role of the brainstem-vermis (BV) angle in the diagnosis of fetal posterior fossa abnormalities at 15-18 weeks' gestation.

METHODS

We examined retrospectively three-dimensional (3D) ultrasound volumes acquired at 15-18 gestational weeks in fetuses with normal posterior fossa (controls) and in those with cystic posterior fossa. Whether the fourth ventricle appeared open posteriorly in axial views was noted and the BV angle was measured. A detailed follow-up was obtained in all cases.

RESULTS

Of the 139 controls, 46 cases were excluded because of inadequate quality of the 3D volumes. Of the 93 remaining normal fetuses, 84 (90.3%) had a closed fourth ventricle and a BV angle < 20°, whereas 9/93 (9.7%) had an open fourth ventricle and a BV angle between 20° and 37°. The study group of 11 fetuses included seven with Dandy-Walker malformation and four with Blake's pouch cyst. In abnormal cases as a whole, the BV angle was significantly increased compared with that in controls (P < 0.0001). However, fetuses with Blake's pouch cyst and normal fetuses with an open fourth ventricle had strikingly similar sonograms: the BV angle was between 20° and 37° and the fourth ventricle appeared open only when viewed using a more steeply angulated scanning plane than that of the standard transcerebellar plane; in fetuses with Dandy-Walker malformation the fourth ventricle was widely open posteriorly, even in the standard transcerebellar view, and the BV angle was > 45°, significantly increased compared both with that in normal fetuses (P < 0.0001) and with that in fetuses with Blake's pouch cyst (P = 0.004).

CONCLUSION

An open fourth ventricle is found in about 10% of normal fetuses at 15-18 weeks' gestation. Measurement of the BV angle is useful in such cases, as a value ≥ 45° is associated with a very high risk of severe posterior fossa malformation.

Fetal posterior fossa dimensions: normal and anomalous development assessed in mid-sagittal cranial plane by three-dimensional multiplanar sonography

OBJECTIVES

To construct nomograms of the dimensions of the fetal posterior fossa (PF), assessed in the mid-sagittal plane in the second and third trimesters, and to assess how measurements from fetuses with PF abnormalities deviate from our normal ranges.

METHODS

This was a prospective cross-sectional study of 378 healthy fetuses in low-risk singleton pregnancies between 15 and 35 weeks. PF size was evaluated in the mid-sagittal plane of the fetal head using three-dimensional multiplanar reconstruction (3D-MPR). The borders of the PF were defined from the clivus to the tentorium (clivotentorial distance, CTD) and from the occipital bone to the level of the upper mesencephalic edge (tecto-occipital distance, TOD), and the posterior fossa area (PFA) and perimeter (PFP) were assessed. Growth charts were produced. Thirty-nine fetuses diagnosed with PF malformations were analyzed by calculating the z-scores of PFA, PFP, TOD and CTD, relative to the developed nomograms.

RESULTS

Of the 378 healthy fetuses initially included, there were 281 with adequate visualization of the PF borders; i.e. PF mid-sagittal plane morphometry was feasible in 74.3% of cases. There was a linear relationship between each of PFA, PFP, TOD and CTD, and gestational age, with Pearson correlation coefficients of 0.97, 0.97, 0.96 and 0.95, respectively (P < 0.001 for each). Chiari II malformation (CM-II) and Dandy-Walker malformation (DWM) were associated with the greatest difference in PF size compared with normal; PFA z-scores exceeded 2.6 in all five DWM cases and were below -2.66 in all 11 CM-II cases.

CONCLUSIONS

Sonographic evaluation of fetal PF size in the mid-sagittal plane is feasible. Our constructed nomograms provide reference data that may be helpful when evaluating PF congenital malformations.

[Dandy-Walker complex: a clinicopathologic study of 9 cases]

OBJECTIVE

To investigate the etiology, pathogenesis, clinicopathologic characteristics, clinical prognosis and treatment of Dandy-Walker syndrome.

METHODS

Nine cases of Dandy-Walker syndrome were included in the study. The autopsy findings and clinical history were evaluated along with review of the literature. The causes, pathogenetic mechanism, pathologic features and prognosis of Dandy-Walker syndrome were analyzed.

RESULTS

Among 9 Dandy-Walker syndrome cases, six patients presented with variants of Dandy-Walker complex and 3 cases had classic Dandy-Walker malformation. In addition, 4 patients presented with combined lateral ventricle expansion and multiple malformations were seen in 7 cases. Combined umbilical cord abnormality was noted in 4 patients with variant of Dandy-Walker complex and combined placental abnormality was seen in one classic Dandy-Walker syndrome.

CONCLUSIONS

Dandy-Walker syndrome is a rare disease. In addition to complex pathogenesis with possible genetic and environmental antigenic etiologies, placental and umbilical cord abnormality may be also related to its development.

First-trimester sonographic findings associated with a Dandy-Walker malformation and inferior vermian hypoplasia

We report 2 cases in which first-trimester measurements of the intracranial translucency and the brain stem-to-occipital bone diameter were markedly enlarged. This finding was thought to represent an abnormal fourth ventricle-cisterna magna complex. Subsequently, the diagnoses of a Dandy-Walker malformation with partial vermian agenesis in 1 case and inferior vermian hypoplasia in the other were established and confirmed by either postmortem autopsy or postnatal magnetic resonance imaging. These cases suggest that evaluation of the fourth ventricle-cisterna magna complex, by measuring the intracranial translucency or brain stem-to-occipital bone diameter may identify some cases with structural malformations of the cerebellum as early as the first trimester.

Ultrasound diagnosis of central nervous system anomalies (bifid choroid plexus, ventriculomegaly, Dandy-Walker malformation) associated with multicystic dysplastic kidney disease in a trisomy 9 fetus: case report with literature review

Trisomy 9 is a lethal chromosomal abnormality that rarely progresses beyond the second trimester of pregnancy. Multiple central nervous system anomalies, including bifid choroid plexus, ventriculomegaly, and Dandy-Walker malformation, associated with multicystic dysplastic kidney disease in a trisomy 9 fetus are reported. The prenatal ultrasound diagnosis has been aided by novel three-dimensional ultrasound software.

[Anormalies of the fetal posterior fossa during second trimester--diagnosis and management]

Six cases of Dandy-Walker malformation are presented. Five of them, diagnosed in 18-20 gestation weeks, respectively ended up in intermission of the pregnancy in second trimester and one case, diagnosed in 29-30 gestation weeks ended up in giving birth to a hypotrophical foetus in a good general state. The opportunities for diagnosis by 2D/3D echography have been considered in accordance with the new classification of abnormality of the fetal posterior fossa fluid collections. This is a clinical approach and a possible way out for the pregnancy and the new-born baby.

Brainstem-vermis and brainstem-tentorium angles allow accurate categorization of fetal upward rotation of cerebellar vermis

OBJECTIVE

To evaluate the role of the brainstem-vermis (BV) and brainstem-tentorium (BT) angles in the differential diagnosis of upward rotation of the fetal cerebellar vermis.

METHODS

The BV and BT angles were measured retrospectively on median sonographic views of the brain in 31 fetuses at 19-28 weeks' gestation with upward rotation of the cerebellar vermis due to Blake's pouch cyst (n = 12), Dandy-Walker malformation (n = 12) and cerebellar vermian hypoplasia (n = 7). Eighty normal fetuses at 20-24 weeks were included as controls.

RESULTS

In the control group, BV and BT angles were 9.1 ± 3.5° (range, 4-17°) and 29.3 ± 5.8° (range, 21-44°), respectively. The BV angle was significantly increased in each of the three subgroups of anomalies: Blake's pouch cyst (23 ± 2.8°; range, 19-26°), vermian hypoplasia (34.9 ± 5.4°; range, 24-40°) and Dandy-Walker malformation (63.5 ± 17.6°; range, 45-112°), the angle increasing with increasing severity of the condition. The BT angle had a similar pattern but there was overlap among the different groups.

CONCLUSION

The BV angle and, to a lesser degree, the BT angle are simple and reproducible measurements that provide valuable additional information for the categorization of upward rotation of the fetal cerebellar vermis. From mid gestation, a BV angle > 45° is strongly suggestive of a Dandy-Walker malformation, while a measurement < 30° favors the diagnosis of a Blake's pouch cyst.

Abnormal or delayed development of the posterior membranous area of the brain: anatomy, ultrasound diagnosis, natural history and outcome of Blake's pouch cyst in the fetus

OBJECTIVES

To review the normal and pathological development of the posterior membranous area (PMA) in the fetal brain, to define sonographic criteria with which to diagnose a Blake's pouch cyst (BPC) in the fetus and to review the ultrasound features, associations and outcome of 19 cases of BPC seen at our center over the last 5 years.

METHODS

We conducted a MEDLINE search using the terms 'Blake's pouch', with or without 'fourth ventricle' or '4(th) ventricle', with or without 'roof' and identified articles describing normal and/or abnormal development of the PMA, whether or not they were cited in the limited clinical literature on BPC. A description of the normal and abnormal development of BPC was derived by collating these articles. The clinical retrospective study included 19 cases of posterior fossa anomalies with a final diagnosis of BPC seen at our institution. The following variables were assessed: referral indication, gestational age at diagnosis, ultrasound and magnetic resonance imaging (MRI) findings, associated anomalies, natural history and pregnancy and neonatal outcome. A transvaginal three-dimensional (3D) ultrasound examination was performed in all cases and 15 cases underwent MRI. To confirm the diagnosis, postnatal MRI, transfontanellar ultrasound or autopsy were available in all cases.

RESULTS

Among the 19 cases reviewed, referral indications were: suspicion of vermian abnormality in 11 (58%) cases and other non-central nervous system anomaly in eight (42%) cases. Sonographically, all cases showed the following three signs: 1) normal anatomy and size of the vermis; 2) mild/moderate anti-clockwise rotation of the vermis; 3) normal size of the cisterna magna. On 3D ultrasound, the upper wall of the cyst was clearly visible in 11/19 cases, with choroid plexuses on the superolateral margin of the cyst roof. On follow-up, the BPC had disappeared by 24-26 gestational weeks in six of the 11 cases which did not undergo termination of pregnancy (TOP), and remained unaltered until birth in the other five cases. There were associated anomalies in eight (42%) cases, in five of which this consisted of or included congenital heart disease. Karyotype was available in 14 cases, two of which were abnormal (both trisomy 21). Regarding pregnancy outcome, there were eight (42%) TOPs, two (10%) neonatal deaths and nine (48%) survivors. One neonate, in whom the BPC had disappeared by the time of birth, had obstructive hydrocephaly confirmed. Another neonate was diagnosed with Down syndrome after birth. Excluding the Down syndrome baby, neurodevelopmental outcome was normal at the time of writing in all eight cases.

CONCLUSIONS

Based on our analysis of ultrasound features, we propose that for BPC to be diagnosed in a fetus the following three criteria should be fulfilled: 1) normal anatomy and size of the vermis; 2) mild/moderate anti-clockwise rotation of the vermis; 3) normal size of the cisterna magna. Furthermore, we found that BPC can undergo delayed fenestration at 24-26 weeks in more than 50% of cases. Finally, it seems that BPC shows a risk of association with extracardiac anomalies (heart defects in particular) and, to a lesser extent, trisomy 21.

Absence of the septum pellucidum associated with a midline fornical nodule and ventriculomegaly: a report of two cases

We report two autopsy cases that revealed the partial absence of the septum pellucidum with ventriculomegaly. In each case, the brain showed mild dilatation of both frontal horns of the lateral ventricles, normal third and fourth ventricles and no aqueductal stenosis. The posterior portion of the septum pellucidum was absent and the fornices were fused in a single midline nodule, abnormally displaced to a caudal position and lodged in the foramina of Monro. The brain base showed no apparent abnormalities; the optic nerves were well developed. We conclude that the caudally displaced fornix in the absence of the septum pellucidum may have intermittently obstructed the foramina of Monro and induced mild ventriculomegaly.

Sonographic findings in a case of tetrasomy 9p associated with increased nuchal translucency and Dandy-Walker malformation

We report a case of a 23-year-old pregnant woman, who underwent amniocentesis after ultrasound (US) examination in the first trimester which revealed a nuchal translucency thickness of 2.9 mm. Cytogenetic analysis revealed complete tetrasomy of the short arm of chromosome 9. Further US evaluation in the second trimester revealed Dandy-Walker malformation, ventriculomegaly, bilateral clubfoot, lip and palate clefts, arthrogryposis and hyperechoic kidneys with bilateral pelvic dilatation. At 30 weeks of gestation, a placental abruption was noted and a Cesarean section was performed. The infant died shortly after birth. A review of previous cases of tetrasomy 9p shows that the remarkable sonographic findings are ventriculomegaly, intrauterine growth restriction, genitourinary anomaly, Dandy-Walker malformation, cleft lip/palate and limb malformation, but the association of tetrasomy 9p and increased nuchal translucency had not been reported.

Sonographic diagnosis of fetal cerebral ventriculomegaly: An update

Dilatation of the fetal cerebral ventricles (ventriculomegaly) is a generic sonographic sign that is common to several pathological entities carrying different prognoses. The main causes of fetal ventriculomegaly are aqueductal stenosis, Chiari II malformation, Dandy-Walker complex, and agenesis of the corpus callosum. Ventriculomegaly is easily recognized by ultrasound by measuring the atrial width. This simple measure allows the recognition of mild forms of ventricular dilatation and is used in screening for ventriculomegaly. However, although the diagnosis of ventriculomegaly is easy, the prenatal identification of the cause of ventricular dilatation is a more difficult task. For this purpose the evaluation of the posterior fossa in association with the visualization of the corpus callosum is useful. Research into the causes of ventriculomegaly is clinically useful, since the prognosis mainly depends on the etiology and on the presence of associated abnormalities. In this article the role of prenatal sonography in determining the cause of the ventriculomegaly is reviewed, as well as the prognostic value of the prenatal sonographic findings.

Occipital intradiploic CSF pseudocyst: an unusual complication of a ventriculoperitoneal shunt malfunction

We report a rare and unique complication of ventriculoperitoneal (VP) shunt malfunction. A progressively expansile, CSF-containing occipital intradiploic cyst developed in a 15-year-old boy at the site of cystoperitoneal shunt draining a Dandy-Walker cyst; the shunt was placed when the boy was 4 years old. A proposed pathogenesis of the lesion is discussed.

[Enlargement of the fetal posterior fossa--what is the significance?]

The posterior fossa may be enlarged due to: mega cisterna magna, arachnoid cyst or Dandy Walker malformation. These anomalies can be identified during routine ultrasound screening performed in the beginning of the second half of pregnancy (22nd week). The outcome of these findings is not clear. Therefore, it is difficult to advise the parents how to manage the pregnancy after the discovery of this anomaly. Most of the studies report a good prognosis in cases of mega cisterna magna or arachnoid cyst, as long as this finding is isolated. A Dandy-Walker malformation or non-isolated enlargement of the posterior fossa entail a guarded prognosis. Further studies are needed in order to enable better counseling.

[Quantitative analysis of cerebellar vermis in fetuses with Dandy-Walker syndrome with three-dimensional ultrasonography]

OBJECTIVE

To evaluate the third plane image of the three-dimensional sonography (3D US) for the quantitative analysis of the cerebellar vermis in normal and Dandy-Walker syndrome (DWS) fetuses.

METHODS

The cerebellar vermis was scanned with trans-abdominal 3D US in the second and third trimesters in 571 normal fetuses and 39 fetuses with Dandy-Walker syndrome. The surface area of the vermis in the mid-sagittal view was measured and calculated. The correlation between the vermian area and the pregnant week was analyzed. The data of vermian area between normal and DWS fetuses was compared.

RESULTS

The vermian area was measured in 529 normal fetuses in the third plane of 3D US. The vermis grew in a linear fashion throughout pregnancy and the growth pattern positively correlated with the gestational age (r2 = 0. 854, P < 0.05). In 39 fetuses with DWS, including 14 with Dandy-Walker malformation (DWM) and 25 with Dandy-Walker variant (DWV), no vermian structure was showed in the mid-sagittal plane in 12 fetuses with DWM and 2 fetuses with DWV, whereas a small vermis appeared in other DWSs.

CONCLUSIONS

The third plane image obtained by 3D US is valuable in studying the fetal cerebellar vermis during the middle and late pregnancy. Knowledge of normal and abnormal vermian appearance may help identify developmental anomalies. Measurement of vermian area in the third plane with 3D US provide a quantitative indicator for prenatal diagnosis of DWS.

MRI and multiplanar 3D ultrasound compared in the prenatal assessment of enlarged posterior fossa

Our aim was to compare the diagnostic capabilities of the multiplanar mode of 3D ultrasound (3D US) and MRI in the assessment of a fetal enlarged cisterna magna. Two fetuses showing an enlarged posterior fossa by conventional two-dimensional ultrasound at 24 and 29 weeks of pregnancy were assessed using both diagnostic methods. One fetus was found to have Dandy-Walker syndrome malformation. In the other, the syndrome was ruled out using both methods. Our results suggest that multiplanar 3D US is able to achieve similar results as does MRI when observing the fetal brain.

Dandy-Walker malformation complex: correlation between ultrasonographic diagnosis and postmortem neuropathology

OBJECTIVE

This autopsy-based study was designed to evaluate sonographic and neuropathologic findings of fetuses diagnosed prenatally with Dandy-Walker malformation complex.

METHODS

The retrospective study encompassed a series of 44 autopsy cases from 2 tertiary referral centers with a prenatal ultrasound diagnosis of Dandy-Walker malformation complex between 1995 and 2003. Ultrasound and pathology data from the cases and from age-matched controls were reviewed in a blinded manner. An unequivocal diagnosis of Dandy-Walker malformation complex from ultrasonography or pathology archival images required significant hypoplasia or aplasia of the cerebellar vermis.

RESULTS

Neuropathologic examination failed to confirm the prenatal diagnosis of Dandy-Walker malformation complex in 59% (26/44, 95% confidence interval [CI] 44-72) of the cases. After standardized reevaluation of high quality archival sonograms and pathology images, concordance remained poor at 55% (6/11 cases, 95% CI 28-79). Sonographic features that favored concordance included marked enlargement of the cisterna magna (> or = 10 mm), complete aplasia of the vermis, and a trapezoid-shaped gap between the cerebellar hemispheres. This latter finding contrasted with a keyhole-shaped gap in fetuses with no cerebellar neuropathology.

CONCLUSION

Correlation between a prenatal ultrasound diagnosis of Dandy-Walker malformation complex and autopsy neuropathology findings is poor. Unequivocal prenatal sonographic diagnosis of Dandy-Walker malformation complex should be reserved for cases with the classic findings of Dandy-Walker malformation, including enlargement of the cisterna magna, aplasia of the vermis, and a trapezoid-shaped, rather than keyhole-shaped, interhemispheric gap.

LEVEL OF EVIDENCE

III.

Posterior fossa malformation in fetuses: a report of 56 further cases and a review of the literature

OBJECTIVE

The purposes of this study were to determine the outcome of fetuses diagnosed as having a posterior fossa abnormality (PFA) and to find out if there are associated features helpful in determining the prognosis.

METHODS

This is a retrospective study of all posterior fossa abnormalities detected prenatally in our Units within the last 10 years. Fifty six patients were selected. Outcome data was collected from the Clinical Genetics Department records and the attending obstetrician or pediatrician.

RESULTS

An enlarged cisterna magna (ECM, diameter greater than 10 mm at 18-23 gw) was detected in 22 fetuses, which was isolated in 14 cases. All the patients followed-up (n = 11) with isolated ECM were normal at birth (100%). Non-isolated ECM was present in 8 cases. Further information was available in 7, 5 (71%) of whom had a poor outcome. A Dandy Walker complex abnormality (DWC) was detected in 34 patients. The majority of them had a poor prognosis, 54% if isolated and 84% if non-isolated.

CONCLUSIONS

Isolated ECM detected on prenatal scans has a favourable outcome, while DWC is associated with a very high chance of a poor prognosis.

Clinical significance of isolated mega cisterna magna

OBJECTIVE

The prevalence and clinical significance of isolated mega cisterna magna in both fetuses and adults is not yet well defined. It is therefore difficult to provide reliable parental counseling in cases of a fetal sonographic diagnosis of this anomaly. The aim of the present study was to, determine the cognitive profile of adults with isolated mega cisterna magna.

METHODS

We reviewed 19,301 consecutive CT/MRI of the brain. Isolated mega cisterna magna was observed in 49 cases. A battery of neuropsychological tests was performed in 18 adults with this anomaly and in 18 controls who had no brain anomaly on CT/MRI.

RESULTS

Subjects with isolated mega cisterna magna had a lower performance on memory tasks [RAVLT saving score (0.8 +/- 0.2 vs. 1.02 +/- 0.2, P = 0.003)] and verbal fluency [phonemic fluency (9.4 +/- 4.5 vs. 13.6 +/- 5.3, P = 0.02), semantic fluency (19.8 +/- 5.8 vs. 24.4 +/- 7.5, P = 0.05)]. They did not differ from controls in regard to the Raven similarity tests indicating that this brain anomaly is not associated with impairment of general cognitive abilities.

CONCLUSION

Adults with isolated mega cisterna have an overall normal cognitive functioning but may score inferior to controls on some parameters of memory and verbal fluency. Although application of adult cases to the fetuses is not well established, this information might be of value in parental counseling in cases of a fetus with this anomaly.

Fetal Diagnosis – Obligations of the Clinician

Fetal echocardiography allows for accurate diagnosis of major heart abnormalities by 16-18 weeks. The parents have up to 22 weeks to consider possible termination. What are the obligations of the clinician once an abnormality is found? Should only information be provided or is there a role in influencing the parents' decision? Two diverse examples are provided to discuss these questions. Mrs A., aged 40 years was noted at the 18-week and then the 20-week scan to have a fetus with a complete atrio-ventricular septal defect. In addition, the fetus had a Danny-Walker cyst. There was thickened nuchal folds and echogenic bowel all suggestive of a chromosomal abnormality. Amniocentesis was refused and the pregnancy continued. Mrs B., aged 34 years was noted at 19 weeks and again at 20 weeks to have a fetus with mild thickening of the walls of both the right and left ventricles. The flow patterns appeared normal. Despite a probable good outlook, the parents asked for a repeat scan at 22 weeks to allow them to consider possible termination. Despite a probable chromosomal abnormality, definite major cardiac and neurological abnormalities, Mrs A. refused karotyping and planned to proceed with the pregnancy. Mrs B., despite a probable good outcome for the fetus asserted pressure for us to prognosticate by 22 weeks. While non-directive counselling is the accepted norm, is that appropriate for all situations? Should one strongly influence Mrs A. to have an amniocentesis to confirm a probable Trisomy thereby allowing her to make a more informed decision? How reassuring can the clinician be to Mrs B. and if termination is sought should one counsel against that? Arguments for these positions are described, highlighting the difficulties faced by clinicians as they counsel parents often with incomplete information and in a setting of acute emotional distress.