Parulekar SV

Hydrocephalus is a condition characterized by excessive cerebrospinal fluid due to disturbed circulation. Its incidence is between 0.2 and 1 per 1000 live births. It is a serious disorder which can cause neonatal death, infant death, mental retardation and morbidity due to associated genetic defects and congenital malformations. It is due to a number of clinicopathological conditions. A large percentage of cases are associated with other intracranial anomalies, like aqueductal stenosis, other neural tube defects, Chiari malformations, Dandy-Walker syndrome, posterior fossa cysts, alobar oloprosencephaly and polymicrogyria. It may be associated with other anomalies, like craniofacial anomalies (cleft lip and/or cleft palate, optic atrophy, low set ears, acrocephalosyndactylia and facial bone anomalies), gastrointestinal anomalies, cardiovascular anomalies, skeletal anomalies, genitourinary anomalie. It may be a part of syndromes like Meckel-Gruber syndrome, Miller-Dieker syndrome and Joubert syndrome. Chromosomal anomalies may be seen in about 20% of cases, such as trisomy 21 and triploidy. X-linked hydrocephalus is reported. Viral infections like tomegalovirus, small pox, rubella, chickenpox, coxsackievirus and herpes simplex can also cause hydrocephalus. Syphilis and toxoplasmosis can also cause the condition. Now Vanessa van der Linden et al have reported a strong association between Zika virus infection and development of hydrocephalus. Maternal diabetes mellitus can be a predisposing factor and needs to be corrected before any intervention is done.

It is essential to detect the disease early with use of ultrasonography and magnetic resonance imaging, so that the progress of the condition and damage to cerebral cortex can be arrested by fetal surgery like ventriculoamniotic shunt under ultrasonographic guidance. The prognosis depends on the underlying cause and presence of associated anomalies. The outcome is better when it is associated with arachnoid cyst, corpus callosum agenesis, atresia of Monro, and fetal intracranial hemorrhage. The outcome is not good when it is associated with encephalocele, holoprosencephaly,  syndromic hydrocephalus, chromosomal errors, and fetal virus infections. Prognosis is better when fetal hydrocephalus begins in the last trimester of gestation as compared to when it develops at the beginning of gestation. These factors need to be borne in mind when making a decision on whether to perform surgery for correction of congenital hydrocephalus. It may be necessary to deliver the woman by a cesarean section in view of fetopelvic disproportion due to large size of the fetal head. In countries where facilities for prenatal diagnosis are not easily available and fetal surgery is not possible, and even antenatal care may not be available to all cases, fetal hydrocephalus may present late in pregnancy or even in labor. Such cases are likely to develop fetal dystocia and maternal complications like uterine rupture. Fetal cerebral tissue may be in the form only a thin mantle and chances of fetal survival are rather poor. The only therapeutic option in such cases may be tapping the hydrocephalus under ultrasonographic control to reduce the size of the very large fetal head and achieve a vaginal delivery.

Our institute has facilities for prenatal diagnosis by ultrasonography and magnetic resonance imaging. Interventional ultrasonography is also possible. On the other hand, we continue to get referred cases with advanced fetal hydrocephalus diagnosed very late. I hope our students and residents benefit from this editorial so that they can manage patients belonging to either group. I also thank all of our contributors and readers, without whose enthusiastic support we would not have been able to complete five years of publication of this journal punctually and successfully.