Two Hundred Thirty-Six Children With Developmental Hydrocephalus: Causes and Clinical Consequences

Choroid plexus-targeted NKCC1 overexpression to treat post-hemorrhagic hydrocephalus

Post-hemorrhagic hydrocephalus (PHH) refers to a life-threatening accumulation of cerebrospinal fluid (CSF) that occurs following intraventricular hemorrhage (IVH). An incomplete understanding of this variably progressive condition has hampered the development of new therapies beyond serial neurosurgical interventions. Here, we show a key role for the bidirectional Na-K-Cl cotransporter, NKCC1, in the choroid plexus (ChP) to mitigate PHH. Mimicking IVH with intraventricular blood led to increased CSF [K+] and triggered cytosolic calcium activity in ChP epithelial cells, which was followed by NKCC1 activation. ChP-targeted adeno-associated viral (AAV)-NKCC1 prevented blood-induced ventriculomegaly and led to persistently increased CSF clearance capacity. These data demonstrate that intraventricular blood triggered a trans-choroidal, NKCC1-dependent CSF clearance mechanism. Inactive, phosphodeficient AAV-NKCC1-NT51 failed to mitigate ventriculomegaly. Excessive CSF [K+] fluctuations correlated with permanent shunting outcome in humans following hemorrhagic stroke, suggesting targeted gene therapy as a potential treatment to mitigate intracranial fluid accumulation following hemorrhage.

The neurodevelopmental outcomes of children with encephalocele: a series of 102 patients

OBJECTIVE

The overall prognosis of encephalocele (EC) is not well described. However, the presence of some risk factors may result in neurodevelopmental delay (NDD) and negatively affect the prognosis of affected patients. The goal of this study was to evaluate neurodevelopmental outcome, as well as the impact of a number of factors on the outcome in patients with ECs.

METHODS

This was an observational, retrospective study including 102 children with EC who were followed at the pediatric neurosurgery department of a tertiary medical center between the years 2010 and 2021. The authors evaluated NDD status according to the Centers for Disease Control and Prevention classification via clinical evaluation and parent interviews in the outpatient setting.

RESULTS

There were 52 boys and 50 girls. The median age at the time of surgery was 4 months (range 1 day-7.5 years). Seventy-one patients (69.6%) had posterior ECs, whereas 31 (30.4%) had anterior ECs. Forty-three (42.2%) of the ECs contained neural tissue. Of the 102 patients, 33 (32.4%) had ventriculomegaly. In terms of NDD, 14 (14.9%) had mild/moderate delay, whereas 17 patients (18.1%) had severe NDD. On univariate analysis, posterior location, size of sac, presence of neural tissue, ventriculomegaly, symptomatic hydrocephalus, and postoperative infection were correlated with NDD. On a multivariate logistic regression model, only neural tissue presence had a statistically significant association with NDD (OR 7.04, 95% CI 1.33-37.2, p = 0.022). Although not statistically significant, children with ventriculomegaly were 2.6 times as likely to have NDD (95% CI 0.59-11.19, p = 0.362).

CONCLUSIONS

This is a single-center study with a large sample size in which the neurodevelopmental status of patients with EC was assessed, and the authors tried to find the risk factors of NDD in these patients. The results showed that the presence of neural tissue within the EC sac was the only risk factor that had independent statistically significant association with NDD.

Hydrocephalus in patients with encephalocele: introduction of a scoring system for estimating the likelihood of hydrocephalus based on an 11-year experience from a tertiary center

OBJECTIVE

The goal of this study was to investigate and identify the predictors associated with the incidence of hydrocephalus requiring shunt insertion in patients with encephalocele (EC), and to develop a scoring system to estimate the probability of hydrocephalus occurrence over time in these patients.

METHODS

A retrospective analysis was undertaken on data from patients treated for EC at a tertiary medical center between 2010 and 2021. Data including patient age at presentation, sex, sac location, sac size, contents, presence of ventriculomegaly/hydrocephalus, CSF leakage, and other associated intracranial/extracranial anomalies were among the variables evaluated for their predictive value. In addition, logistic regression analyses were performed to identify the independent predictors. A predictive scoring system was developed based on regression coefficients.

RESULTS

A total of 102 cases of EC were identified. The patient group consisted of 52 boys and 50 girls. Seventy-one patients (69.6%) had posterior ECs. Forty-three (42.2%) of the ECs contained neural tissue. Thirty-three patients presented with ventriculomegaly (32.4%), 30 of whom (90.9%) underwent ventriculoperitoneal shunt placement for hydrocephalus. Multivariate analysis revealed that the presence of other associated anomalies (OR 2.8, 95% CI 1.1-7.4, p = 0.027), larger EC sac size (OR 1.3, 95% CI 1.01-1.6, p = 0.042), and infections (OR 6.8, 95% CI 1.3-34.8, p = 0.034) were associated with ventriculomegaly. The logistic regression model consisted of 5 variables including the patients' history of meningitis, their sex, sac location, sac size, and presence of other other associated anomalies; analysis resulted in the maximum accuracy of 86% for the prediction of hydrocephalus occurrence.

CONCLUSIONS

According to the findings, the presence of other associated anomalies, a larger sac, and infections are significant independent predictors of hydrocephalus. By considering these 3 predictors as well as sac location and the patient's sex, it will be possible to predict hydrocephalus occurrence in patients with EC with significant accuracy.

Periventricular hypodensity is associated with the incidence of pre-shunt seizure in hydrocephalic children

BACKGROUND

The seizure incidence in hydrocephalic children has been acknowledged in a lot of studies previously; nonetheless, seizure pathogenesis in these children remains unclear. Its high proportion of hydrocephalic children who underwent shunt surgery suggests that the seizure might be associated with the protocol of shunt placement and/or the shunt existence intracranially; however, this hypothesis could not explain the pre-shunt seizure incidence in hydrocephalic children.

OBJECTIVE

This study aims to evaluate the patients' characteristics and CT findings in pre-shunt hydrocephalic children to identify the possible seizure etiology in these patients.

METHODS

Three hundred and thirty-four children with hydrocephalus were included in this study, including 147 hydrocephalic children with the pre-shunt seizure history and 187 hydrocephalic children presented without the pre-shunt seizure history. The following information was retrieved from the patients' medical records: gender, age, pediatric Glasgow Coma Scale (pGCS) upon admission, and hydrocephalus diagnoses. CT findings were re-evaluated to assess the compression association of sulci and gyri, Sylvian fissures, cisterns, FH/ID ratio, Evan's ratio, and periventricular hypodensity with pre-shunt seizure.

RESULTS

The results show that the pre-shunt seizure incidence is significantly higher in hydrocephalic children aged 1 to 5 years old (63/113 (55%), p = 0.0001), diagnosed with communicating hydrocephalus (97/163 (59%), p = 0.0001) or infectious hydrocephalus (80/109 (73%), p = 0.0001). The presence of periventricular hypodensity is significantly associated with the pre-shunt seizure incidence (132/205 (64.3%), p = 0.0001). Results from univariate analyses suggest significant association between periventricular hypodensity in every location and pre-shunt seizure (p < 0.0001). Multivariate analyses identify that temporal horn in the right lateral ventricle as the location of periventricular hypodensity has the strongest association with the pre-shunt seizure.

CONCLUSION

The presence of periventricular hypodensity in head CT scan is significantly associated with the pre-shunt seizure incidence. Further investigation to confirm this finding and evaluate the possible roles of inflammation in the pre-shunt seizure in hydrocephalic children is important to seek its possible implication on the treatment of pre-shunt seizure in these children.

Endoscopic third ventriculostomy in children with chronic communicating congenital hydrocephalus: a single-center cohort retrospective analysis

OBJECTIVE

The aim of this study was to analyze the role of endoscopic third ventriculostomy (ETV) in the treatment of pediatric chronic communicating congenital hydrocephalus (CCCH).

MATERIAL AND METHODS

This retrospective study comprised a series of 11 children with CCCH treated with ETV. Data were recorded on gender, history, presenting symptoms, age at surgery, complications during surgery, clinical evolution, ETV survival, and follow-up period. Radiological variables including ventricular and cephalic diameters were also recorded to determine a series of ventricular indexes in magnetic resonance imaging (MRI) before and after the ETV procedure. The procedure was considered to be successful when there was clinical stability or improvement accompanied by a reduction in the radiological indexes in the postoperative control images, such that there was no need to place an extrathecal cerebrospinal fluid shunt.

RESULTS

Over a mean follow-up period of 35.8 months (range: 6-108 months) from the ETV procedure, three patients required shunt placement; one of these was due to early failure in an 8-month old girl, the only patient younger than 12 months in our series. The radiological indexes were reduced in all patients except for one of the cases of ETV failure. The mean ETV survival among the successful cases was 32.1 months (range: 6-108 months), whilst that of the failed cases was 16 months (range: 6-108 months).

CONCLUSION

Although studies with larger sample sizes are needed, ETV appears to be a promising option for the treatment of this type of patient with CCCH.

Bilateral hyperplasia of choroid plexus with severe CSF production: a case report and review of the glymphatic system

BACKGROUND

An important feature of hydrocephalus is the alteration of the cerebral spinal fluid (CSF) homeostasis. New insights in the understanding of production, secretion, and absorption of CSF, along with the discovery of the glymphatic system (GS), can be useful for a better understanding and treatment of hydrocephalus in disorders with CSF overproduction.

CASE DESCRIPTION

A 1-year-old patient was diagnosed with communicating hydrocephalus; ventricle peritoneal shunt (VPS) is installed and ascites developed. VPS is exposed, yielding volumes of 1000-1200ml/day CSF per day. MRI is performed showing generalized choroidal plexus hyperplasia. Bilateral endoscopic coagulation of thechoroid plexus was performed in 2 stages (CPC) however the high rate of CSF production persisted, needing a bilateral plexectomy through septostomy, which finally decreased the CSF outflow.

DISCUSSION

New knowledge about the CSF physiology will help to propose better treatment depending on the cause of the hydrocephalus. The GS is becoming an additional reason to better study and develop new therapies focused of the modulation of alternative CSF reabsorption.

CONCLUSION

Despite the current knowledge about hydrocephalus, we remain without a complete understanding of the pathophysiology of this condition. GS could be more important than conventional concept of reabsorption of CSF in the arachnoid villi, therefore GS could be a new key point, which will guide future investigations.

Genetics and Molecular Pathogenesis of Human Hydrocephalus

Hydrocephalus is a neurological disorder with an incidence of 80-125 per 100,000 live births in the United States. The molecular pathogenesis of this multidimensional disorder is complex and has both genetic and environmental influences. This review aims to discuss the genetic and molecular alterations described in human hydrocephalus, from well-characterized, heritable forms of hydrocephalus (e.g., X-linked hydrocephalus from L1CAM variants) to those affecting cilia motility and other complex pathologies such as neural tube defects and Dandy-Walker syndrome. Ventricular zone disruption is one key pattern among congenital and acquired forms of hydrocephalus, with abnormalities in cadherins, which mediate neuroepithelium/ependymal cell junctions and contribute to the pathogenesis and severity of the disease. Given the relationship between hydrocephalus pathogenesis and neurodevelopment, future research should elucidate the genetic and molecular mechanisms that regulate ventricular zone integrity and stem cell biology.

Genetic etiologies associated with infantile hydrocephalus in a Chinese infantile cohort

BACKGROUND

Infantile hydrocephalus (IHC) is commonly related to other central nervous system diseases, which may have adverse effects on prognosis. The causes of IHC are heterogeneous, and the genetic etiologies are not fully understood. This study aimed to analyze the genetic etiologies of an IHC cohort.

METHODS

The data for 110 IHC patients who had received exome sequencing at the Clinical Genetic Center of the Children's Hospital of Fudan University between 2016 and 2019 were reviewed and analyzed retrospectively. An exome-wide association analysis (EWAS) was performed within this cohort using IHC as the study phenotype.

RESULTS

Of the 110 IHC patients, a pathogenic or likely pathogenic variant was identified in 16 (15%) patients, spanning 13 genes. The genes were mainly associated with metabolic disorders, brain abnormalities, and genetic syndromes. IHC patients who had unclear clinical etiology were more likely to possess a genetic etiology. Based on previous studies and on our EWAS results, ZEB1, SBF2, and GNAI2 were over-represented among IHC patients and might affect the signaling pathways involved in IHC formation.

CONCLUSIONS

Our study showed heterogeneous genetic etiologies in an IHC cohort. It is essential to perform genetic testing on IHC patients who have unclear clinical etiology, and genes associated with metabolic disorders, brain abnormalities, and genetic syndromes should be noted. In addition, when aiming to discover IHC susceptibility genes, genes that might influence the signaling pathways involved in IHC formation should be prioritized.

Prognostic Analysis and Risk Factors Associated with Fetal Ventriculomegaly

BACKGROUND

This study aimed to investigate the clinical outcome and related risk factors of fetal lateral ventriculomegaly (VM).

METHODS

A retrospective analysis was performed on 255 cases diagnosed as fetal VM. Prenatal imaging examination was carried out. The pregnancy outcomes were investigated through follow-up. According to the prognosis of children, they were divided into case group and control group. Multivariate logistic regression was used to analyze the factors influencing the prognosis of hydrocephalus.

RESULTS

After excluding the cases with either loss of follow-up or incomplete information, 102 cases were followed up. Twelve cases with poor prognosis were set as the case group. According to the maternal age, gestational age, gender of children, and follow-up time, 3 cases were selected from the other 90 cases for each child in the case group, respectively, and selected as the control group. Paired comparative analysis was performed on 48 cases. Using prognosis as a dependent variable, multivariate logistic regression analysis of the statistically significant factors indicated that the change speed of width ratio (CSWR) and maximum lateral ventricular width (MW) were associated with fetal prognosis.

CONCLUSIONS

Our results suggested that CSWR and MW may have the value of predicting fetal prognosis.

Management of Hydrocephalus in Children: Anatomic Imaging Appearances of CSF Shunts and Their Complications

OBJECTIVE. This article addresses the management of hydrocephalus and the CSF shunts used to treat this entity. CONCLUSION. CSF shunts have a high failure rate. Imaging plays a pivotal role in assessing CSF shunt failure and determining the need for surgical revision. An in-depth knowledge of CSF shunt components, their failure modes, and the corresponding findings on anatomic imaging studies is necessary to ensure timely diagnosis and prevent permanent neurologic damage.

Risk and risk factors for epilepsy in shunt-treated children with hydrocephalus

OBJECT

Epilepsy is a major comorbidity in children with hydrocephalus (HC) and has a serious impact on their developmental outcomes. There are variable influencing factors, thus the individual risk for developing epilepsy remains unclear. Our aim was to analyse risk factors for developing epilepsy in children with shunted HC.

METHODS

A retrospective, single-centre analysis of 361 patients with the diagnosis of HC was performed. Age at HC diagnosis, shunt treatment, development of epilepsy, epilepsy course, and the aetiology of HC were considered. The influence of shunt therapy, including its revisions and complications, on the development of epilepsy was investigated.

RESULTS

One-hundred forty-three patients with HC (n = 361) had a diagnosis of epilepsy (39.6%). The median age at the first manifestation of epilepsy was 300 days (range:1-6791; Q1:30, Q3: 1493). The probability of developing epilepsy after HC decreases with increasing age. The most significant influence on the development of epilepsy is that of the HC itself and its underlying aetiology (HR 5.9; 95%-CI [3-10.5]; p < 0.001). Among those, brain haemorrhage is associated with the highest risk for epilepsy (HR 7.9; 95%-CI [4.2-14.7]; p < 0.01), while shunt insertion has a lower influence (HR 1.5; 95%-CI [0.99; 2.38]; p = 0.06). The probability of epilepsy increases stepwise per shunt revision (HR 2.0; p = 0.03 after 3 or more revisions). Five hundred days after the development of HC, 20% of the children had a diagnosis of epilepsy. Shunt implantation at a younger age has no significant influence on the development of epilepsy nor does sex.

CONCLUSION

Children with HC are at high risk for developing epilepsy. The development of epilepsy is correlated mainly with HC's underlying aetiology. The highest risk factor for the development of epilepsy seems to be brain haemorrhage. The age at shunt implantation appears to be unrelated to the development of epilepsy, while structural brain damage at a young age, shunt revisions and complications are independent risk factors. The onset of epilepsy is most likely to take place within the first 500 days after the diagnosis of HC.

PI3K-Yap activity drives cortical gyrification and hydrocephalus in mice

Mechanisms driving the initiation of brain folding are incompletely understood. We have previously characterized mouse models recapitulating human PIK3CA-related brain overgrowth, epilepsy, dysplastic gyrification and hydrocephalus (Roy et al., 2015). Using the same, highly regulatable brain-specific model, here we report PI3K-dependent mechanisms underlying gyrification of the normally smooth mouse cortex, and hydrocephalus. We demonstrate that a brief embryonic Pik3ca activation was sufficient to drive subtle changes in apical cell adhesion and subcellular Yap translocation, causing focal proliferation and subsequent initiation of the stereotypic ‘gyrification sequence’, seen in naturally gyrencephalic mammals. Treatment with verteporfin, a nuclear Yap inhibitor, restored apical surface integrity, normalized proliferation, attenuated gyrification and rescued the associated hydrocephalus, highlighting the interrelated role of regulated PI3K-Yap signaling in normal neural-ependymal development. Our data defines apical cell-adhesion as the earliest known substrate for cortical gyrification. In addition, our preclinical results support the testing of Yap-related small-molecule therapeutics for developmental hydrocephalus.

Fetal and neonatal neurogenetics

Disorders of the developing nervous system may be of genetic origin, comprising congenital malformations of spine and brain as well as metabolic or vascular disorders that affect normal brain development. Acquired causes include congenital infections, hypoxic-ischemic or traumatic brain injury, and a number of rare neoplasms. This chapter focuses on the clinical presentation and workup of neurogenetic disorders presenting in the fetal or neonatal period. After a summary of the most frequent clinical presentations, clues from history taking and clinical examination are illustrated with short case reports. This is followed by a discussion of the different tools available for the workup of neurogenetic disorders, including the various genetic techniques with their advantages and disadvantages. The implications of a molecular genetic diagnosis for the patient and family are addressed in the section on counseling. The chapter concludes with a proposed workflow that may help the clinician when confronted with a potential neurogenetic disorder in the fetal or neonatal period.

De Novo Mutation in Genes Regulating Neural Stem Cell Fate in Human Congenital Hydrocephalus

Congenital hydrocephalus (CH), featuring markedly enlarged brain ventricles, is thought to arise from failed cerebrospinal fluid (CSF) homeostasis and is treated with lifelong surgical CSF shunting with substantial morbidity. CH pathogenesis is poorly understood. Exome sequencing of 125 CH trios and 52 additional probands identified three genes with significant burden of rare damaging de novo or transmitted mutations: TRIM71 (p = 2.15 × 10-7), SMARCC1 (p = 8.15 × 10-10), and PTCH1 (p = 1.06 × 10-6). Additionally, two de novo duplications were identified at the SHH locus, encoding the PTCH1 ligand (p = 1.2 × 10-4). Together, these probands account for ∼10% of studied cases. Strikingly, all four genes are required for neural tube development and regulate ventricular zone neural stem cell fate. These results implicate impaired neurogenesis (rather than active CSF accumulation) in the pathogenesis of a subset of CH patients, with potential diagnostic, prognostic, and therapeutic ramifications.

Magnetic resonance imaging findings in newly diagnosed epileptic children

Objectives

Epilepsy is one of the most common chronic neurologic disorders in childhood and it affects 0.5-1% of children. The purpose of the study was to determine the prevalence and types of structural abnormalities in the epileptic children.

Methods

The study was performed in Near East University and Dr. Suat Gunsel University in North Cyprus. It was conducted at pediatric neurology outpatient clinic of the hospital. The records of 1 to 18 years old epileptic children in whom Magnetic Resonance Imaging (MRI) performed within 6 months after diagnosis were enrolled to the study between the dates of October 2011 and June 2017.

Results

Among 220 children; 131 (59.55%) had no abnormality and 89 (45.45%) had at least one abnormality in the MRI. Most commonly documented lesions were generally encephalomalacia, hydrocephaly and brain atrophy with a percent of 5.90 (13 cases), 5.45 (12 cases) and 4.55 (10 cases) respectively. Sixty nine (31.06%) of the patients had one abnormality whereas 20 (9.09%) had two or more lesion.

Conclusion

Abnormality in MRI examination in newly diagnosed epileptic children was high. These high rates may be due to enrollment of children with new emerging epilepsy on a chronical neurologic disorder. Additionally 20 (9.09%) of patients had a concomitant lesion. Secondary lesions were detected in cases with corpus callosum abnormality, atrophy, encephalomalacia and hydrocephaly. Primarily formed lesions are unknown; further studies are needed to confirm these findings.

Hydrocephalus in children under the age of five from diagnosis to short-/medium-/long-term progression: a retrospective review of 142 children

The aim of this study is to evaluate the clinical history and prognosis of children with early-onset hydrocephalus. The retrospective study's inclusion criteria were hydrocephalus diagnosis before the age of 5 years, independent of aetiology, and birth details, January 1, 2000 to December 31, 2014. Overall, 142 children were entered into the study, divided into 11 aetiological groups: premature-birth post-intraventricular haemorrhage (16%), brain tumours (16%), spina bifida (15%), aqueductal stenosis (8%), post-meningitis (8%), post-haemorrhage (8%), Dandy-Walker malformation (6%), unknown origin (6%), arachnoid cyst (5%), miscellaneous obstruction (4%), and various causes (8%). In total, 23 patients died, primarily from the tumour group. Ventriculostomy, performed 42 times, was successful in 20 patients. Overall, 226 internal shunts were placed in 99 children. Infectious complications affected 19% of children after shunt placement and 51% after mechanical complications. Mean follow-up was 4 years 10 months, with 61% of children progressing fairly well, especially those with aqueductal stenosis, cysts, and unknown or diverse obstructive causes. Post-meningitis hydrocephalus displayed the poorest outcome. Isolated obstructive hydrocephalus exhibited better prognosis, with most obstructive aetiologies effectively treated via ventriculostomy. Children treated by shunt placement were more at risk of complications. Aetiologies with associated abnormalities and neurological sequelae had poorer outcomes.

Bi-allelic mutations of CCDC88C are a rare cause of severe congenital hydrocephalus

Congenital or infantile hydrocephalus is caused by genetic and non-genetic factors and is highly heterogeneous in etiology. In recent studies, a limited number of genetic causes of hydrocephalus have been identified. To date, recessive mutations in the CCDC88C gene have been identified as a cause of non-syndromic congenital hydrocephalus in three reported families. Here, we report the fourth known family with two affected individuals with congenital hydrocephalus due to a homozygous mutation in the CCDC88C gene identified by whole exome sequencing. Our two newly described children, as well as the previously published ones, all shared several features including severe infantile-onset hydrocephalus, mild to severe intellectual delay, varying degrees of motor delay, and infantile onset seizures. All identified homozygous mutations in CCDC88C abolish the PDZ binding site necessary for proper CCDC88C protein function in the Wnt signaling pathway. Our report further establishes CCDC88C as one of the few known recessive causes of severe prenatal-onset hydrocephalus. Recognition of this syndrome has important diagnostic and genetic implications for families identified in the future.

Surprisingly good outcome in antenatal diagnosis of severe hydrocephalus related to CCDC88C deficiency

Non-syndromic congenital hydrocephalus is aetiologically diverse and while a genetic cause is frequently suspected, it often cannot be confirmed. The most common genetic cause is L1CAM-related X-linked hydrocephalus and that explains only 5%-10% of all male cases. This underlines a current limitation in our understanding of the genetic burden of non-syndromic congenital hydrocephalus, especially for those cases with likely autosomal recessive inheritance. Additionally, the prognosis for most cases of severe congenital hydrocephalus is poor, with most of the surviving infants displaying significant intellectual impairment despite surgical intervention. It is for this reason that couples with an antenatal diagnosis of severe hydrocephalus are given the option, and may opt, for termination of the pregnancy. We present two families with CCDC88C-related recessive congenital hydrocephalus with children who had severe hydrocephalus. Those individuals who were shunted within the first few weeks of life, who did not require multiple surgical revisions, and who had a more distal truncating variant of the CCDC88C gene met their early childhood developmental milestones in some cases. This suggests that children with CCDC88C-related autosomal recessive hydrocephalus can have normal developmental outcomes under certain circumstances. We recommend CCDC88C analysis in cases of severe non-syndromic congenital hydrocephalus, especially when aqueduct stenosis with or without a medial diverticulum is seen, in order to aid prognosis discussion.

MR Imaging Diagnosis of Diencephalic-Mesencephalic Junction Dysplasia in Fetuses with Developmental Ventriculomegaly

Diencephalic-mesencephalic junction dysplasia is a rare malformation characterized by a poorly defined junction between the diencephalon and the mesencephalon, associated with a characteristic butterfly-like contour of the midbrain (butterfly sign). This condition may be variably associated with other brain malformations, including callosal abnormalities and supratentorial ventricular dilation, and is a potential cause of developmental hydrocephalus. Here, we have reported 13 fetuses with second-trimester obstructive ventriculomegaly and MR features of diencephalic-mesencephalic junction dysplasia, correlating the fetal imaging with available pathology and/or postnatal data. The butterfly sign can be clearly detected on axial images on fetal MR imaging, thus allowing for the prenatal diagnosis of diencephalic-mesencephalic junction dysplasia, with possible implications for the surgical management of hydrocephalus and parental counseling.

Cerebrospinal fluid hypersecretion in pediatric hydrocephalus

Hydrocephalus, despite its heterogeneous causes, is ultimately a disease of disordered CSF homeostasis that results in pathological expansion of the cerebral ventricles. Our current understanding of the pathophysiology of hydrocephalus is inadequate but evolving. Over this past century, the majority of hydrocephalus cases has been explained by functional or anatomical obstructions to bulk CSF flow. More recently, hydrodynamic models of hydrocephalus have emphasized the role of abnormal intracranial pulsations in disease pathogenesis. Here, the authors review the molecular mechanisms of CSF secretion by the choroid plexus epithelium, the most efficient and actively secreting epithelium in the human body, and provide experimental and clinical evidence for the role of increased CSF production in hydrocephalus. Although the choroid plexus epithelium might have only an indirect influence on the pathogenesis of many types of pediatric hydrocephalus, the ability to modify CSF secretion with drugs newer than acetazolamide or furosemide would be an invaluable component of future therapies to alleviate permanent shunt dependence. Investigation into the human genetics of developmental hydrocephalus and choroid plexus hyperplasia, and the molecular physiology of the ion channels and transporters responsible for CSF secretion, might yield novel targets that could be exploited for pharmacotherapeutic intervention.