Fetal aqueductal stenosis: Prenatal diagnosis and intervention

Expanding the phenotypic spectrum of LIG4 pathogenic variations: neuro-histopathological description of 4 fetuses with stenosis of the aqueduct

Severe ventriculomegaly is a rare congenital brain defect, usually detected in utero, of poor neurodevelopmental prognosis. This ventricular enlargement can be the consequence of different mechanisms: either by a disruption of the cerebrospinal fluid circulation or abnormalities of its production/absorption. The aqueduct stenosis is one of the most frequent causes of obstructive ventriculomegaly, however, fewer than 10 genes have been linked to this condition and molecular bases remain often unknown. We report here 4 fetuses from 2 unrelated families presenting with ventriculomegaly at prenatal ultra-sonography as well as an aqueduct stenosis and skeletal abnormalities as revealed by fetal autopsy. Genome sequencing identified biallelic pathogenic variations in LIG4, a DNA-repair gene responsible for the LIG4 syndrome which associates a wide range of clinical manifestations including developmental delay, microcephaly, short stature, radiation hypersensitivity and immunodeficiency. Thus, not only this report expands the phenotype spectrum of LIG4-related disorders, adding ventriculomegaly due to aqueduct stenosis, but we also provide the first neuropathological description of fetuses carrying LIG4 pathogenic biallelic variations.

Open Fetal Surgery for Ventricular-Amniotic Valve Implantation in Aqueductal Stenosis-Dependent Severe Fetal Hydrocephalus: A Case Report with 7-Year Follow-Up

INTRODUCTION

Fetal ventriculomegaly is one of the most commonly diagnosed central nervous system pathologies of the second trimester, occurring with a frequency of 0.3-0.5/1,000 births. Severe fetal ventriculomegaly (SVM) may necessitate intrauterine intervention. Most such interventions have been made percutaneously with ultrasound guidance insertion of a pigtail catheter, which sadly often became obstructed or migrated.

CASE PRESENTATION

Our case report presents the possibility of ventriculo-amniotic valve implantation (VAVI) by classic hysterotomy in isolated severe fetal hydrocephalus (IVSM) due to aqueductal stenosis. The patient was operated on similarly to open fetal surgery MOMS criteria at 24+4/7 GA, with an initial lateral ventricular dimension of 22.5 mm. A female newborn was delivered by elective cesarean section at 31+1/7 GA due to PPROM (Apgar 10' 8 points, birth weight 1,600 g), required CPAP, and removal of the drainage system due to infection and narrow lateral ventricles. Evans index (EI) gradual increase and clinical symptoms of high-pressure hydrocephalus after 10 days required a ventricle-peritoneal shunt (VPS) implantation. The newborn was discharged home after 28 days with stabile hydrocephalus (EI: 0.59-0.6), in good clinical condition. The 7-year follow-up was complicated by epilepsy, VPS shunt infections, delay in motor and intellectual functions (mild to moderate), and symptoms of atypical autism, the phenotype possibly related to a variant in ZEB2 gene.

CONCLUSION

Intrauterine VAVI is a one-step procedure that is effective in draining CFS. The limitations of the method remain complications due to preterm labor and infection of the drainage system.

Prenatal Diagnosis of Fetal Aqueductal Stenosis: A Multicenter Prospective Observational Study through the North American Fetal Therapy Network

INTRODUCTION

A critical component of an evidence-based reassessment of in-utero intervention for fetal aqueductal stenosis (fetal AS) is determining if the prenatal diagnosis can be accurately made at a gestational age amenable to in-utero intervention.

METHODS

A multicenter, prospective, observational study was conducted through the North American Fetal Therapy Network (NAFTNet). Pregnancies complicated by severe central nervous system (CNS) ventriculomegaly (lateral ventricle diameter >15 mm) not secondary to a primary diagnosis (myelomeningocele, encephalocele, etc.) were recruited at diagnosis. Imaging and laboratory findings were recorded in an online REDCap database. After evaluation, investigators were asked to render their degree of confidence in the diagnosis of fetal AS. The prenatal diagnosis was compared to the postnatal diagnosis obtained through neonatal neuroimaging. Performance characteristics of ultrasound and magnetic resonance imaging (MRI) were calculated, as was the mean gestational age at diagnosis.

RESULTS

Between April 2015 and October 2022, eleven NAFTNet centers contributed 64 subjects with severe fetal CNS ventriculomegaly. Of these, 56 had both prenatal and postnatal diagnoses recorded. Ultrasound revealed 32 fetal AS true positives, 4 false positives, 7 false negatives, and 13 true negatives, rendering a sensitivity of 0.82, a specificity of 0.76, a positive predictive value of 0.89, and a negative predictive value of 0.65. The mean gestational age at diagnosis by ultrasound was 25.5 weeks (std +/- 4.7 weeks). The proportion of agreement (true positive + true negative/n) was highest at 24 weeks gestation. For fetal MRI (n = 35), the sensitivity for fetal AS was 0.95, specificity was 0.69, positive predictive value was 0.84, and negative predictive value was 0.90. MRI was performed at 25 weeks on average.

CONCLUSION

The prenatal diagnosis of fetal AS can be made with accuracy at a gestational age potentially amenable to in-utero intervention. Only 7% of subjects were incorrectly diagnosed prenatally with fetal AS by ultrasound and 11% by MRI. Diagnostic accuracy of fetal AS will likely improve with increased experience.

Percutaneous fetal endoscopic third ventriculostomy for severe isolated cerebral ventriculomegaly

OBJECTIVE

To demonstrate the feasibility and preliminary results of percutaneous fetal endoscopic third ventriculostomy (ETV) in human fetuses (pfETV) with isolated progressive and/or severe bilateral cerebral ventriculomegaly (IPSBV).

METHODS

The initial results of pfETV for IPSBV were described. Perioperative, perinatal and postnatal variables were described. The Ages and Stages Questionnaire (ASQ-3), 3rd edition (ASQ-3) was used for follow-up of all infants.

RESULTS

Successful pfETV was performed in 10/11 (91%) fetuses, at a median gestational age (GA) of 28.7 weeks (25.3-30.7). There were no perioperative complications. After pfETV, 70% (7/10) of the fetuses had a decreased or stabilized lateral ventricle atria|lateral ventricle's atria. The median GA at delivery was 38.2 weeks (35.9-39.3). There were no perinatal complications. The postnatal ventriculoperitoneal shunt rate was 80% (8/10). Among neonates/infants who had prenatal stabilization or a decrease in the LVAs, 4 (4/7: 57.1%) had abnormal scores on the ASQ-3. Among neonates/infants that experienced prenatal increases in the LVAs, all of them (3/3: 100%) had abnormal scores on the ASQ-3.

CONCLUSION

Percutaneous ETV is feasible in human fetuses with progressive and/or severe cerebral ventriculomegaly and seems to be a safe procedure for both the mother and the fetus.

In vitro and in vivo assessment of a novel ultra-flexible ventriculoamniotic shunt for treating fetal hydrocephalus

Fetal aqueductal stenosis (AS) is one of the most common causes of congenital hydrocephalus, which increases intracranial pressure due to partial or complete obstruction of cerebrospinal fluid (CSF) flow within the ventricular system. Approximately 2-4 infants per 10,000 births develop AS, which leads to progressive hydrocephalus, which enlarges the head often necessitating delivery by cesarean section. Most babies born with AS are severely neurologically impaired and experience a lifetime of disability. Therefore, a new device technology for venticuloamniotic shunting is urgently needed and has been studied to ameliorate or prevent fetal hydrocephalus development, which can provide a significant impact on patients and their family's quality of life and on the decrease of the healthcare dollars spent for the treatment. This study has successfully validated the design of shunt devices and demonstrated the mechanical performance and valve functions. A functional prototype shunt has been fabricated and subsequently used in multiple in vitro tests to demonstrate the performance of this newly developed ventriculoamniotic shunt. The shunt contains a main silicone-nitinol composite tube, a superelastic 90° angled dual dumbbell anchor, and an ePTFE valve encased by a stainless-steel cage. The anchor will change its diameter from 1.15 mm (collapsed state) to 2.75 mm (deployed state) showing up to 1.4-fold diameter change in human body temperature. Flow rates in shunts were quantified to demonstrate the valve function in low flow rates mimicking the fetal hydrocephalus condition showing "no backflow" for the valved shunt while there is up to 15 mL/h flow through the shunt with pressure difference of 20 Pa. In vivo ovine study results show the initial successful device delivery and flow drainage with sheep model.

Role of fetal MRI to diagnose abnormal cerebral ventricular system and associated fetal brain anomalies

Background

Abnormal cerebral ventricular system is one of the most common clinical indications for fetal MRI, mainly to detect other associated abnormalities that can be occult on prenatal ultrasonography. Although using ultrasound can identify most anomalies, MRI is known to be superior in identifying CNS anomalies as it has higher contrast resolution for brain parenchymal assessment added to the fact of being less affected by fetal positioning, oligohydramnios, maternal obesity, and reverberation artifacts. Fetal brain ventriculomegaly is defined as atrial width of > 10 mm on sonography, measured in the axial plane, at the level of the frontal horns, cavum septi pellucidi, and glomus of the choroid plexus perpendicular to the long axis of the lateral ventricle. One of the most important factors determining the fetal neurological outcome is the presence and severity of additional CNS anomalies that are better clarified by MRI. The aim of this study is to establish the role of fetal MRI in detecting the association between abnormal cerebral ventricular system and other CNS anomalies, correlation with the severity of ventriculomegaly and ventricle asymmetry.

Results

Thirty pregnancies with fetal brain abnormal ventricular system were included in this study, 5 cases with isolated corpus callosum (CC) agenesis (16.666%); 2 cases with cystic lesions [one interhemispheric and the other dorsal] (6.666%) both associated with CC agenesis; 1 case with alobar holoprosencephaly (3.333%) associated with CC agenesis; 2 cases with semi-lobar holoprosencephaly (6.666%) [associated with CC agenesis and one of them is also associated with lissencephaly]; 3 cases with Dandy–Walker Malformation (DWM) (10%) [2 isolated and 1 associated with CC agenesis]; 3 cases with Dandy–Walker Variants (DWV) (10%) [1 isolated and 2 associated with CC agenesis]; 2 cases with Joubert syndrome (6.666%); 1 case isolated lissencephaly (3.333%); 4 cases of obstructive ventriculomegaly (13.333%) (1 of which associated with CC agenesis); 1 case of Arnold Chiari malformation type II (3.333%) associated with CC agenesis; 2 cases with meningoceles (6.666%) (occipital and parieto-occipital); 1 case with Mega cisterna Magna (3.333%); 1 case with anencephaly (3.333%); 1 case with right hemimegalencephaly (3.333%) (associated with frontal meningocele and CC agenesis); and 1 case with grade IV germinal matrix hemorrhage (3.333%). The pregnancies resulted in 20 births (66.66%), 2 died directly after birth (6.66%), 5 terminations (16.66%), and 3 intrauterine fetal deaths (IUFD) (10%). We found that the frequency of associated CNS anomalies was strongly related to the width of the ventricle. The association between CNS findings and ventricle width was particularly evident in sever ventriculomegaly. The greater the width of the ventricular system, the more the risk of associated CNS anomalies. Only one case showed diffusion restriction and was diagnosed to be of hemorrhagic nature. The relation between symmetry and degree of ventriculomegaly was found to be statistically insignificant (P = 0.115). Assessment of different fetal brain congenital anomalies was not significantly affected by the using of DWI sequence as it is a functional modality rather than being a tool for assessment of anatomical gross abnormalities.

Conclusions

Fetal MRI is an important adjuvant to US in cases of ventriculomegaly particularly those associated with complex CNS anomalies. The association between CNS findings and ventricular dilatation was particularly evident in sever ventriculomegaly. The greater the width of the ventricular system, the more the risk of associated CNS anomalies. Fetal MRI may also be helpful in doubtful cases that could be misdiagnosed as ventriculomegaly including holoprosencephaly, hydranencephaly, porencephaly, and various supratentorial cystic lesions. DWI confirms the diagnosis of hemorrhage.

Fetal cerebral ventriculomegaly: What do we tell the prospective parents?

Fetal cerebral ventriculomegaly is a relatively common finding, observed during approximately 1% of obstetric ultrasounds. In the second and third trimester, mild (≥10 mm) and severe ventriculomegaly (≥15 mm) are defined according to the measurement of distal lateral ventricles that is included in the routine sonographic examination of central nervous system. A detailed neurosonography and anatomy ultrasound should be performed to detect other associated anomalies in the central nervous system and in other systems, respectively. Fetal MRI might be useful when neurosonography is unavailable or suboptimal. The risk of chromosomal and non-chromosomal genetic disorders associated with ventriculomegaly is high, therefore invasive genetic testing, including microarray, is recommended. Screening for prenatal infections, in particular cytomegalovirus and toxoplasmosis, should also be carried out at diagnosis. The prognosis is determined by the severity of ventriculomegaly and/or by the presence of co-existing abnormalities. Fetal ventriculoamniotic shunting in progressive isolated severe ventriculomegaly is an experimental procedure. After delivery, ventricular-peritoneal shunting or ventriculostomy are the two available options to treat hydrocephalus in specific conditions with similar long-term outcomes. A multidisciplinary fetal neurology team, including perinatologists, geneticists, pediatric neurologists, neuroradiologists and neurosurgeons, can provide parents with the most thorough prenatal counseling. This review outlines the latest evidence on diagnosis and management of pregnancies complicated by fetal cerebral ventriculomegaly.

Novel prenatally diagnosed compound heterozygous POMT2 variants in fetal congenital primary aqueduct stenosis

OBJECTIVE

To study the etiology of congenital hydrocephalus in genetic aqueduct stenosis.

CASE REPORT

We report the case of a 31-year-old pregnant female, G2P0A1, with a history of hyperthyroidism under medical control. The patient received regular prenatal care, with no specific findings in the Level II ultrasound at 21 weeks of gestation. However, hydrocephalus was noted at GA 31 weeks. High-resolution sonography and fetal magnetic resonance imaging (MRI) reported fetal aqueduct stenosis. Maternal HSV, CMV, and toxoplasma infection were not detected. Fetal karyotype and chromosomal microarray analysis (CMA) indicated a normal. After intensive counseling, the parents decided to terminate the pregnancy due to the poor fetal prognosis. Post-mortem, a whole-exome sequencing (WES) and Sanger sequencing analysis trio study identified two compound heterozygous variants in the POMT2 gene inherited from both recessive parents. In the subsequent pregnancy, a WES survey revealed inheritance of only the maternal POMT2 gene variant; a live, healthy male baby was born.

CONCLUSION

Extended WES represents a precision maternal medicine tool for novel prenatal diagnosis of congenital aqueduct stenosis.

Severe fetal ventriculomegaly: Fetal morbidity and mortality, caesarean delivery rates and obstetrical challenges in a large prospective cohort

INTRODUCTION

Severe fetal ventriculomegaly (VM) is defined as an enlargement of the atria of the lateral cerebral ventricles (Vp) of greater than 15 mm. While it is well established that it confers significant risk of morbidity and mortality to the neonate, there is limited information pertaining to the caesarean delivery rates and the obstetric management of these complex cases. The aim of this study was twofold: firstly, to determine survival rates in fetuses with severe VM, and secondly to determine the caesarean delivery rates in continuing pregnancies. We explore the obstetric challenges associated with these difficult cases.

METHODS

This was a prospective observational study of patients with antenatal severe VM, attending the Department of Fetal Medicine, National Maternity Hospital, Dublin, Ireland, from 1st January 2011 to 31st July 2020. Data were obtained from the hospital database and those with severe VM (Vp > 15 mm) were identified. The rates of chromosomal abnormalities, the survival rates and the caesarean delivery (CD) rates for the overall group were then determined. The data were then further sub-divided into two groups: 1. Vp < 20 mm and 2. Vp > 20 mm, and the results compared. Statistical analysis was performed using the Chi-Square test.

RESULTS

A total of N = 95 pregnancies with severe VM were included for analysis, of which additional structural abnormalities on ultrasound were apparent in 67/95 (70.5%) and 28/95 (29.5%) had isolated severe VM. Chromosomal abnormalities were diagnosed in 15/95 (15.8%) of cases, with (2/28) 7.1% in the isolated SVM group versus (13/67) 19.4% in the non-isolated SVM group. The overall survival rate (excluding TOP) was 53/74 (71.6%), with 20/23 (86.9%) in the isolated SVM group. The overall CD rate was 47/72 (65.3%), which was significantly higher than the CD for the hospital during the same time period of 25.4% (P < 0.01). The data were subdivided into Vp < 20 and Vp > 20 and those with a Vp > 20 had higher rates of additional intracranial findings on ultrasound (Vp < 20 13/41 (31.7%) versus Vp > 20 32/54 (59.3%) (P < 0.05)) and macrocrania (Vp < 20 14/41 (34.1%) versus Vp > 20 35/54 (64.8%) (P < 0.05)). No significant difference was observed in the overall survival or CD rates between the two groups.

CONCLUSION

In conclusion this study reports significant fetal morbidity and mortality with severe VM with high CD rates observed in this cohort. Significant challenges exist in relation to the obstetric management and counseling of parents regarding an often uncertain neonatal prognosis. In continuing pregnancies with significant macrocrania delivery plans should be individualized to improve neonatal outcomes where possible and minimize harm to the mother.

Neuroophthalmological manifestations of congenital aqueductal stenosis

OBJECTIVE

Congenital aqueductal stenosis (CAS) is a common etiology of hydrocephalus that occurs in a subset of infants and may be linked to an increased incidence of ophthalmological abnormalities and delayed developmental milestones. Although hydrocephalus is common and widely studied, sparse literature exists on patients with isolated (no identifiable genetic link) CAS along with analysis of ophthalmological manifestations. In this study, the authors sought to describe the ophthalmological abnormalities and delayed developmental milestones of patients with isolated CAS.

METHODS

Data of patients with CAS were prospectively entered and monitored in a surgical database maintained by the Department of Neurological Surgery at Children's Hospital of Pittsburgh from January 2005 to October 2016. Patients with a family history of congenital hydrocephalus, positive testing for genetic forms of aqueductal stenosis, other congenital abnormalities suggesting an underlying genetic syndrome, and stenosis/obstruction due to secondary causes were excluded from this study. Prenatal and perinatal history, CSF diversion history, and a variety of outcomes, including ophthalmological deficits and developmental milestones, were collected and analyzed.

RESULTS

A total of 41 patients with isolated CAS were identified, with a mean follow-up duration of 6 years. Among that cohort, 26 patients (63.4%) developed neuroophthalmological complications, which were further stratified. Fourteen patients (34.1%) developed strabismus and 11 (26.8%) developed astigmatism, and 1 patient (2.4%) with papilledema was recorded. Among patients with ophthalmological abnormalities, 76.9% had delayed developmental milestones (p = 0.045).

CONCLUSIONS

Patients with CAS were found to have increased risk of ophthalmological abnormalities requiring correction, along with an increased risk of delayed developmental milestones. Importantly, there was a significant correlation between the development of ophthalmological abnormalities and delayed developmental milestones that was independent of CSF diversion history. Larger patient cohort studies are required to explore whether earlier development of hydrocephalus, as is the case in CAS, causes elevated rates of neurological and ophthalmological complications, and if earlier CSF diversion correlates with improved outcomes.

Fetal therapy for congenital hydrocephalus-where we came from and where we are going

Despite unfavorable outcomes during the early experience with in utero intervention for congenital hydrocephalus, improvements in prenatal diagnosis, patient selection, and fetal surgery techniques have led to a renewed interest in fetal intervention for congenital hydrocephalus. Research studies and clinical evidence shows that postnatal cerebrospinal fluid diversion to release intraventricular pressure and cerebral mantle compression usually arrives late to avoid irreversible brain damage. Make sense to decompress those lateral ventricles as soon as possible during the intrauterine life when hydrocephalus is antenatally detected. We present a historical review of research in animal models as well as clinical experience in the last decades, traveling until the last years when some research fetal therapy groups have made significant progress in recapitulating the prenatal intervention for fetuses with congenital obstructive hydrocephalus.