Interpeduncular angle: A new parameter for assessing intracranial hypotension in fetuses with spinal dysraphism

Prenatal intracranial hypotension syndrome in congenital cephalocele: Insights into pathophysiologic mechanisms and importance of defect coverage

OBJECTIVE

To compare specific fetal cranial and cerebral findings indicative of prenatal intracranial hypotension (PICH) syndrome between open and closed cephaloceles.

METHODS

Two groups of fetuses with cephalocele who underwent magnetic resonance imaging scan were selected based on the defect coverage: covered ("closed cephalocele" group, n = 4) and uncovered by skin ("open cephalocele" group, n = 8). The presence of signs associated with PICH syndrome was evaluated and findings compared between groups.

RESULTS

Cases from the open cephalocele group showed statistically significant differences in comparison with the closed cephalocele group regarding reduction of the interpeduncular angle (p = 0.006), reduced amount of cerebrospinal fluid in the subarachnoid space (p = 0.01), collapsed/severely reduced fourth ventricle (p = 0.03), cephalocele content (p = 0.03), and identification of a vector traction (p = 0.03). There were no differences in the presence of cerebellar tonsillar descent, obstructive ventriculomegaly, and presence of the lemon sign. In comparison with gestational age-matched controls, only the biparietal diameter but not the head circumference was significantly smaller in both the open and closed cephalocele groups (p < 0.05).

CONCLUSION

Congenital cephaloceles present distinct imaging behavior depending on the defect coverage. Therefore, the classification of cephalocele should include, in addition to location and content, the presence or absence of skin fully covering the defect.

Applicability of a semiautomated volumetric approach (5D CNS+™) for detailed antenatal reconstruction of abnormal fetal CNS anatomy

BACKGROUND

The aim of this study was to evaluate the accuracy and reliability of a semiautomated volumetric approach (5D CNS+™) when examining fetuses with an apparent abnormal anatomy of the central nervous system (CNS).

METHODS

Stored 3D volumes extracted from a cohort of > 1.400 consecutive 2nd and 3rd trimester pregnancies (range 15-36 gestational weeks) were analyzed using the semiautomatic software tool 5D CNS+™, enabling detailed reconstruction of nine diagnostic planes of the fetal brain. All 3D data sets were examined and judged for plane accuracy, the need for manual adjustment, and fetal CNS anomalies affecting successful plane reconstruction.

RESULTS

Based on our data of 91 fetuses with structural cerebral anomalies, we were able to reveal details of a wide range of CNS anomalies with application of the 5D CNS+™ technique. The corresponding anatomical features and consecutive changes of neighboring structures could be clearly demonstrated. Thus, a profound assessment of the entire altered CNS anatomy could be achieved in nearly all cases. The comparison with matched controls showed a significant difference in volume acquisition (p < 0.001) and in need for manual adjustment (p < 0.001) but not in the drop-out rates (p = 0.677) of both groups.

CONCLUSION

5D CNS+™ is applicable in the majority of cases with brain lesions and constitutes a reliable tool even if the integrity of the fetal CNS is compromised by structural anomalies. Using volume data that were acquired in identical cutting sections needed for conventional biometry allows for detailed anatomic surveys grossly independent of the examiner's experience.

Correlation of fetal ventricular size and need for postnatal cerebrospinal fluid diversion surgery in open spina bifida

OBJECTIVES

Open spina bifida is a common cause of hydrocephalus in the postnatal period. In-utero closure of the fetal spinal defect decreases the need for postnatal cerebrospinal fluid (CSF) diversion surgery. Good prenatal predictors of the need for postnatal CSF diversion surgery are currently lacking. In this study, we aimed to assess the association of fetal ventriculomegaly and its progression over the course of pregnancy with the rate of postnatal hydrocephalus requiring intervention.

METHODS

In this retrospective study, fetuses with a prenatal diagnosis of open spina bifida were assessed longitudinally. Ventricular diameter, as well as other potential predictors of the need for postnatal CSF diversion surgery, were compared between fetuses undergoing prenatal closure and those undergoing postnatal repair.

RESULTS

The diameter of the lateral ventricle increased significantly throughout gestation in both groups, but there was no difference in maximum ventricular diameter at first or last assessment between fetuses undergoing prenatal closure and those undergoing postnatal repair. There was no significant difference in the rate of progression of ventriculomegaly between the two groups, with a mean progression rate of 0.83 ± 0.5 mm/week in the prenatal-repair group and 0.6 ± 0.6 mm/week in the postnatal-repair group (P = 0.098). Fetal repair of open spina bifida was associated with a lower rate of postnatal CSF diversion surgery (P < 0.001). In all subjects, regardless of whether they had prenatal or postnatal surgery, the severity of ventriculomegaly at first and last assessments was associated independently with the need for postnatal CSF diversion surgery (P = 0.005 and P = 0.001, respectively), with a greater need for surgery in fetuses with larger ventricular size, even after controlling for gestational age at assessment.

CONCLUSIONS

In fetuses with open spina bifida, fetal ventricular size increases regardless of whether spina bifida closure is performed prenatally or postnatally, but the need for CSF diversion surgery is significantly lower in those undergoing prenatal repair. Ventriculomegaly is associated independently with the need for postnatal CSF diversion in fetuses with open spina bifida, irrespective of timing of closure. © 2021 International Society of Ultrasound in Obstetrics and Gynecology.

Brain Doppler abnormalities in fetuses with open spina bifida

BACKGROUND

To describe the brain Doppler changes in fetuses with isolated open spina bifida (OSB).

STUDY DESIGN

Doppler ultrasound measurements including the umbilical artery (UA) pulsatility index (PI), middle cerebral artery (MCA) PI, and their combination into the cerebroplacental ratio (CPR) and umbilicocerebral ratio (UCR) were performed in a cohort of fetuses with OSB. Included patients were individually matched to a control group without structural anomalies and similar gestational ages. MCA-PI and/or CPR values below the 5th centile were considered abnormal and indicative of cerebral blood redistribution, while UCR and UA-PI above the 95th centile were considered abnormal.

RESULTS

During the study period, 266 fetuses were recruited, 133 normally grown fetuses with OSB and 133 matched controls. Doppler recordings were successfully obtained in all fetuses at a median gestational age of 30.9 weeks. All cases showed UA-PI within normal ranges, but fetuses with OSB showed significantly higher frequency of cerebral blood redistribution (15.0 vs. 3.0%, p < .01), MCA-PI <5th centile (10.5% vs. 3.0%, p = .01), decreased CPR (9.8% vs. 2.3%, p = .01) and increased UCR (17.2 % vs 7.5 %, p =.02). The rate of cerebral blood redistribution was significantly higher in the OSB group with ventriculomegaly in comparison to those with OSB and normal lateral ventricle diameter (18.6% vs. 3.2%, respectively; p <.05).

CONCLUSION

A proportion of fetuses with isolated open spina bifida showed cerebral blood redistribution.

Open intrauterine repair of spina bifida aperta: Historical aspects, current availability, and clinical outcomes from the Latin American Spina Bifida Consortium

OBJECTIVE

To determine the historical aspects, current availability, and clinical outcomes of open intrauterine repair of spina bifida aperta (IRSBA) in Spanish-speaking Latin American countries.

METHODS

Cases were collected from centers with at least 2 years of experience and a minimum of 10 open IRSBA interventions by December 2020. Clinical variables were compared to the results of the Management of Myelomeningocele Study (MOMS) trial.

RESULTS

Clinical experience with 314 cases from seven centers was reviewed. Most cases (n = 189, 60.2%) were performed between 24 and 25.9 weeks' gestation. Delivery at less than 30 weeks' gestation occurred in 36 cases (11.5%) and the overall perinatal mortality rate was 5.4% (17 of 314). The rate of maternal complications was low, including the need for blood transfusion (n = 3, 0.9%) and dehiscence or a thin uterine scar (n = 4, 1.3%). No cases of maternal death were recorded. Fifteen neonates required additional surgical repair of the spinal defect (4.8%) and 63 of 167 infants (37.7%) required a cerebrospinal fluid diversion procedure. Only two of the seven centers reported preliminary experience with fetoscopic IRSBA.

CONCLUSIONS

Clinical experience and outcomes were within the expected results reported by the MOMS trial. There is still very limited experience with fetoscopic IRSBA in this part of the world.

Prenatal intracranial hypotension syndrome: new insights into the mechanisms of fenestration of septi pellucidi and ventriculomegaly in fetuses with open spinal dysraphism

OBJECTIVE

To study the prevalence of abnormalities of the septi pellucidi (SP) in a cohort of fetuses with open spinal dysraphism (OSD) and to determine whether this condition is secondary to obstructive ventriculomegaly and, therefore, part of the natural history of prenatal intracranial hypotension (PICH) syndrome.

METHODS

Magnetic resonance imaging (MRI) studies from fetuses with OSD were analyzed. The SP were assessed using axial and coronal T2-weighted images of the fetal brain and classified as intact, partially absent, or completely absent. Additionally, the correlation between the presence or absence of the SP and the size of the lateral ventricles, degree of cerebellar tonsillar herniation, collapse of the fourth ventricle, and interpeduncular angle was investigated.

RESULTS

A total of 32 fetuses with OSD were studied. Mean gestational age at the time of the fetal MRI was 25.5 ± 3.9 weeks (range, 19-35) and mean ventricular size was 16.2 ± 4.2 mm (range, 8-26). Twenty-three (71.9%) fetuses had cerebellar tonsillar herniation. The IPA was completely collapsed in 23 cases (71.9%), reduced in seven (21.9%), and unreadable in two (6.3%). Twenty (62.5%) fetuses presented with intact SP, 10 (31.3%) with partially absent SP (incomplete fenestration), and two (6.3%) with completely absent SP (complete fenestration). Fenestration of the SP correlated significantly with the degree of ventriculomegaly (Pearson's correlation coefficient =0.459; p = .01). However, there was no correlation with the IPA, collapse of the fourth ventricle, and cerebellar tonsillar herniation.

CONCLUSIONS

More than one-third of the fetuses with OSD had fenestration of the SP. The most probable etiology is increased intraventricular pressure leading to local necrosis of the SP. As fenestration of the SP is a secondary event associated with PICH syndrome, this condition should not be considered a contraindication for intrauterine repair of the spinal defect. Instead, it should be seen as an indicator of the severity of the intraventricular pressure.