Hydrocephalic holoprosencephaly: An oxymoron? Insights into etiology and management

Prenatal diagnosis of syndromic alobar holoprosencephaly associated with digynic triploidy fetus

Holoprosencephaly (HPE) is a dramatic human brain malformation sequence with an extreme variable phenotypic spectrum and genetic heterogeneity, variable degree of severity and unknown etiology, in many cases. HPE is classified into syndromic, chromosomal, and non-syndromic, non-chromosomal. The most cases of HPE are syndromic. We present an atypical case of syndromic alobar HPE associated with digynic triploidy fetus, prenatally diagnosed, early at 18 weeks of gestation, by ultrasound (US) and complex genetic investigations. The US examination was performed with a specialized US machine, General Electric Voluson E10 OLED BT18, using two-dimensional (2D) scanning, three-dimensional (3D) image reconstruction, four-dimensional (4D) spatiotemporal image methodology and the highest power Doppler US technology. A detailed US examination of the fetus revealed several major abnormalities of the fetal head and severe facial malformations. Based on the antenatal US findings, the fetus was diagnosed with alobar HPE. After a careful examination and genetic counseling, additional cytogenetic investigations and molecular genetic analyses were performed, which revealed an abnormal number of 69 chromosomes, digynic triploidy (69,XXY). Two days later, the parents choose to interrupt the current gestation because of major fetal malformations. The pathological examination of the embryo reaffirmed the antenatal diagnostics.

Ventriculoperitoneal Shunting in Alobar Holoprosencephaly: Does it Work Even When Patient Has No Sign of Raised Intracranial Pressure?

Holoprosencephaly (HPE) is a developmental anomaly of forebrain characterized by a failure of division of the embryonic forebrain into hemispheres. It is associated with a set of facial anomalies at a rate of 80%. Survival rate, particularly in alobar HPE, is quite low. Alobar HPE is usually associated with a large dorsal cyst which might eventually lead to hydrocephalus and raised intracranial pressure. Placement of ventriculoperitoneal (VP) shunt has been reported to be beneficial in symptomatic hydrocephalus accompanying HPE. Here we report a preterm infant born with alobar HPE and undergoing VP shunt placement although there was no sign of raised intracranial pressure. She is 12 months old now having near-normal developmental progress. This case has revealed that the placement of VP shunt, particularly inserting the catheter tip into dorsal cyst of HPE, might be beneficial and contribute to the survival and further brain development even in the absence of the signs of raised intracranial pressure.

Management Strategies for Hydrocephalus in Alobar Holoprosencephaly: A Case Report and Discussion

Holoprosencephaly is a rare congenital malformation resulting from an impaired midline division of the prosencephalon into distinct cerebral hemispheres. Hydrocephalus is a frequent problem among the few survivors with alobar holoprosencephaly (aHPE), its most severe form. The literature about neurosurgical management of hydrocephalus in this condition is limited and dispersed, and there are still some points that need to be resolved. We report the case of a newborn with aHPE, hydrocephalus, and central diabetes insipidus. We delineate the complexity of the management of these patients and emphasize the benefits of using an initial programmable shunt valve. Further discussion about management strategies includes reviewing previous reports and the benefits of shunting for hypothalamic osmoreceptor function.