Congenital hydrocephalus is a prevalent condition, that leads to fetal cerebral ventricle dilation and increased intracranial pressure. It is associated with significant neurological impairments, partly due to the disruption of neurogenesis and gliogenesis.
Panventriculomegaly with a wide foramen of Magendie and a large cisterna magna may belong to a subtype of congenital hydrocephalus with familial accumulation, younger age at onset, and symptoms of normal pressure hydrocephalus. In addition, a family with PaVM has a gene mutation associated with dysfunction of motile cilia 1).
Congenital hydrocephalus is present at birth and can be caused by a variety of factors, often linked to abnormal brain development during gestation. Some of the common causes include:
#### a. Aqueductal Stenosis
#### b. Chiari Malformation
#### c. Genetic and Environmental Factors
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Duy et al. found convergence of congenital hydrocephalus risk genes in embryonic neuroepithelial stem cells. Of all CH risk genes, TRIM71/lin-41 harbors the most de novo mutations and is most specifically expressed in neuroepithelial cells. Mice harboring neuroepithelial cell-specific Trim71 deletion or CH-specific Trim71 mutation exhibit prenatal hydrocephalus. CH mutations disrupt TRIM71 binding to its RNA targets, causing premature neuroepithelial cell differentiation and reduced neurogenesis. Cortical hypoplasia leads to a hypercompliant cortex and secondary ventricular enlargement without primary defects in CSF circulation. These data highlight the importance of precisely regulated neuroepithelial cell fate for normal brain-CSF biomechanics and support a clinically relevant neuroprogenitor-based paradigm of CH 2).
Secondary to intra-uterine germinal matrix hemorrhage or intraventricular hemorrhage.
Few systematic assessments of developmental forms of hydrocephalus exist. Tully et al reviewed magnetic resonance images (MRIs) and clinical records of patients with infancy-onset hydrocephalus. Among 411 infants, 236 had hydrocephalus with no recognizable extrinsic cause. These children were assigned to 1 of 5 subtypes and compared on the basis of clinical characteristics and developmental and surgical outcomes. At an average age of 5.3 years, 72% of children were walking independently and 87% could eat by mouth; in addition, 18% had epilepsy. Distinct patterns of associated malformations and syndromes were observed within each subtype. On average, children with aqueductal obstruction, cysts, and encephaloceles had worse clinical outcomes than those with other forms of developmental hydrocephalus. Overall, 53% of surgically treated patients experienced at least 1 shunt failure, but hydrocephalus associated with posterior fossa crowding required fewer shunt revisions. We conclude that each subtype of developmental hydrocephalus is associated with distinct clinical characteristics, syndromology, and outcomes, suggesting differences in underlying mechanisms 3).
Integrating human brain transcriptomics with whole-exome sequencing of 483 patients with congenital hydrocephalus (CH), Duy et al. found convergence of CH risk genes in embryonic neuroepithelial stem cells. Of all CH risk genes, TRIM71/lin-41 harbors the most de novo mutations and is most specifically expressed in neuroepithelial cells. Mice harboring neuroepithelial cell-specific Trim71 deletion or CH-specific Trim71 mutation exhibit prenatal hydrocephalus. CH mutations disrupt TRIM71 binding to its RNA targets, causing premature neuroepithelial cell differentiation and reduced neurogenesis. Cortical hypoplasia leads to a hypercompliant cortex and secondary ventricular enlargement without primary defects in CSF circulation. These data highlight the importance of precisely regulated neuroepithelial cell fate for normal brain-CSF biomechanics and support a clinically relevant neuroprogenitor-based paradigm of CH 4).
Karakaya et al. aims to investigate alterations in the proliferation and differentiation of neural progenitor cells (NPCs) in a fetal lamb model of obstructive HCP induced by intracisternal BioGlue injection, to identify the potential optimal intervention time for prenatal surgery.
This study involved 22 fetal lambs, divided into control (n = 10) and HCP (n = 12) groups with hydrocephalus induced at approximately 85-90 gestational days. Histological and molecular techniques, including hematoxylin and eosin staining, triple immunofluorescence, Western blot analysis, and RT-qPCR, were utilized to assess changes in NPCs, astrocytes, and oligodendrocytes across three different gestational stages (E105, E125, and E140). The analysis of data was done by using multiple (unpaired) two-sample t-test and was represented as mean and standard deviation.
HCP led to significant disruptions in the ventricular zone (VZ), with the translocation of NPCs into the intraventricular CSF and formation of periventricular heterotopias. This study revealed an initial surge in the expression of NPC markers (Pax6 and Sox2), which decreased as HCP progressed. Astroglia reaction intensified, as indicated by increased expression of GFAP, vimentin, and aquaporin 4, particularly at later stages of pregnancy (p < 0.001, p < 0.001 and p < 0.001, control and HCP E140, respectively). Myelin formation was also adversely affected, with reduced expression of oligodendrocyte markers (Olig2 and Sox10, p = 0.01 and p = 0.009, control and HCP E140, respectively) and myelin proteins (MOBP, MOG and MBP, p = 0.02, p = 0.049 and p = 0.02 control and HCP E140, respectively).
This study contributed to clarify the profound impact of congenital HCP on neurogenesis and gliogenesis in an experimental fetal lamb model. The VZ disruption and altered expression of key neurogenic and glial markers suggested a significant pathological process underlying neurodevelopmental abnormalities. The findings suggested a potential window for prenatal surgical intervention between E105 and E125 in the sheep model, offering new avenues for prenatal therapeutic approaches and improving surgical outcomes in affected fetuses and neonates 5)