Fetal Intraventricular Hemorrhage in Open Neural Tube Defects: Prenatal Imaging Evaluation and Perinatal Outcomes

BACKGROUND AND PURPOSE

Fetal imaging is crucial in the evaluation of open neural tube defects. The identification of intraventricular hemorrhage prenatally has unclear clinical implications. We aimed to explore fetal imaging findings in open neural tube defects and evaluate associations between intraventricular hemorrhage with prenatal and postnatal hindbrain herniation, postnatal intraventricular hemorrhage, and ventricular shunt placement.

MATERIALS AND METHODS

After institutional review board approval, open neural tube defect cases evaluated by prenatal sonography between January 1, 2013 and April 24, 2018 were enrolled (n = 504). The presence of intraventricular hemorrhage and gray matter heterotopia by both prenatal sonography and MR imaging studies was used for classification. Cases of intraventricular hemorrhage had intraventricular hemorrhage without gray matter heterotopia (n = 33) and controls had neither intraventricular hemorrhage nor gray matter heterotopia (n = 229). A total of 135 subjects with findings of gray matter heterotopia were excluded. Outcomes were compared with regression analyses.

RESULTS

Prenatal and postnatal hindbrain herniation and postnatal intraventricular hemorrhage were more frequent in cases of prenatal intraventricular hemorrhage compared with controls (97% versus 79%, 50% versus 25%, and 63% versus 12%, respectively). Increased third ventricular diameter, specifically >1 mm, predicted hindbrain herniation (OR = 3.7 [95% CI, 1.5-11]) independent of lateral ventricular size and prenatal intraventricular hemorrhage. Fetal closure (n = 86) was independently protective against postnatal hindbrain herniation (OR = 0.04 [95% CI, 0.01-0.15]) and postnatal intraventricular hemorrhage (OR = 0.2 [95% CI, 0.02-0.98]). Prenatal intraventricular hemorrhage was not associated with ventricular shunt placement.

CONCLUSIONS

Intraventricular hemorrhage is relatively common in the prenatal evaluation of open neural tube defects. Hindbrain herniation is more common in cases of intraventricular hemorrhage, but in association with increased third ventricular size. Fetal closure reverses hindbrain herniation and decreases the rate of intraventricular hemorrhage postnatally, regardless of the presence of prenatal intraventricular hemorrhage.

Myelomeningocele sac associated with worse lower-extremity neurological sequelae: evidence for prenatal neural stretch injury?

OBJECTIVE

To determine whether the presence of a myelomeningocele (MMC) sac and sac size correlate with compromised lower-extremity function in fetuses with open spinal dysraphism.

METHODS

A radiology database search was performed to identify cases of MMC and myeloschisis (MS) diagnosed prenatally in a single center from 2013 to 2017. All cases were evaluated between 18 and 25 weeks. Ultrasound reports were reviewed for talipes and impaired lower-extremity motion. In MMC cases, sac volume was calculated from ultrasound measurements. Magnetic resonance imaging reports were reviewed for hindbrain herniation. The association of presence of a MMC sac and sac size with talipes and impaired lower-extremity motion was assessed. Post-hoc analysis of data from the multicenter Management of Myelomeningocele Study (MOMS) randomized controlled trial was performed to confirm the study findings.

RESULTS

In total, 283 MMC and 121 MS cases were identified. MMC was associated with a lower incidence of hindbrain herniation than was MS (80.9% vs 100%; P < 0.001). Compared with MS cases, MMC cases with hindbrain herniation had a higher rate of talipes (28.4% vs 16.5%, P = 0.02) and of talipes or lower-extremity impairment (34.9% vs 19.0%, P = 0.002). Although there was a higher rate of impaired lower-extremity motion alone in MMC cases with hindbrain herniation than in MS cases, the difference was not statistically significant (6.6% vs 2.5%; P = 0.13). Among MMC cases with hindbrain herniation, mean sac volume was higher in those associated with talipes compared with those without talipes (4.7 ± 4.2 vs 3.0 ± 2.6 mL; P = 0.002). Review of the MOMS data demonstrated similar findings; cases with a sac on baseline imaging had a higher incidence of talipes than did those without a sac (28.2% vs 7.5%; P = 0.007).

CONCLUSIONS

In fetuses with open spinal dysraphism, the presence of a MMC sac was associated with fetal talipes, and this effect was correlated with sac size. The presence of a larger sac in fetuses with open spinal dysraphism may result in additional injury through mechanical stretching of the nerves, suggesting another acquired mechanism of injury to the exposed spinal tissue. Copyright © 2019 ISUOG. Published by John Wiley & Sons Ltd.

Modification of multiple transcriptional regulatory elements in a Moloney murine leukemia virus gene transfer vector circumvents silencing in fibroblast grafts and increases levels of expression of the transferred enzyme

Down-regulation of retroviral vector expression occurs in a number of cell types after transplantation. Although a number of vector elements have been shown to affect expression in specific experimental situations, the results can vary depending on the specific cDNA being expressed, the individual retroviral elements included in vectors, the promoter, or the inclusion of selectable markers. In previous experiments with the lysosomal enzyme beta-glucuronidase, silencing has occurred in more than 95% of transduced cells regardless of the position of the expression unit within the vector, whether a eukaryotic or viral promoter was used, whether a bacterial selectable marker gene was present or not, the target cell type, or the species of the host. It has been a consistent finding that a small number of continuously expressing cells persist for long periods after transplantation. In this study we found that deletion of all the transcriptional regulatory elements from the vector LTR, inclusion of a permissive primer binding site sequence, and use of a eukaryotic housekeeping promoter could greatly increase the number of expressing cells in fibroblast grafts in subcutaneous neo-organs and in the brain. Furthermore, the level of enzyme expression was increased five-fold on a per positive cell basis, indicating that the deleted regulatory elements were exerting a negative effect on expression in the few cells that were positive before modification of the vector. This resulted in more than a 50-fold increase in total activity compared with the previous highest expressing vector.

Accumulation of abnormal amounts of glycosaminoglycans in murine mucopolysaccharidosis type VII neural progenitor cells does not alter the growth rate or efficiency of differentiation into neurons

Mucopolysaccharidosis type VII (MPS VII) results from deficiencies in the gene encoding the lysosomal enzyme beta-glucuronidase (GUSB). To study how the genetic and biochemical defects of MPS disease affect neural cell populations, neural progenitor cells (NPCs) were isolated from MPS VII mice and normal littermates. After growth in culture, approximately 90% of cells from both genotypes were nestin positive, a marker for NPCs, and lacked markers associated with lineage commitment. The mutant NPCs contained elevated levels of undegraded glycosaminoglycans (GAGs), the substrate for GUSB. Transduction with a retrovirus-vector expressing normal GUSB resulted in correction of the biochemical defects. Because of the demonstrated roles that GAGs and proteoglycans have in NPC biology and neural development, we tested whether the alterations in GAG metabolism affected MPS VII NPC properties regulated by GAG-containing molecules. MPS VII NPC cultures had growth rates in response to FGF-2 that were similar to normal cultures and the efficiency of differentiation into neurons was the same as with normal cells. Thus, even though isolated NPCs accumulate abnormally high levels of GAGs, these two key developmental properties were not altered when the cells were examined outside the milieu of the diseased brain.