**Abstract**

Hydrocephalus (HCP) is one of the most common associations of myelomeningocele, and it may be overt and present at birth or be latent and develop following the repair of myelomeningocele. In patients with myelomeningocele, aqueductal stenosis, fourth ventricular obstruction, subarachnoid obstruction at the tentorial hiatus, and the crowded posterior fossa, which are all related to Chiari II malformation, are the various causes of hydrocephalus. The clinical manifestations depend on the age at presentation, but most patients present with macrocephaly and craniofacial disproportion, increasing head size, bulging anterior fontanelle, calvaria sutural diastasis, distended scalp veins, poor feeding as well as signs of raised intracranial pressure such as vomiting, headache, and altered consciousness. Diagnosis is based on clinical features and supportive radiological investigations such as transcranial ultrasound, brain computerized tomographic scan, and brain magnetic resonance imaging. Prompt treatment is very important to obtain optimal clinical outcomes, and this may be by inserting a shunt or performing endoscopic third ventriculostomy with or without choroid plexus cauterization.

**Keywords:** hydrocephalus, myelomeningocele, ventriculoperitoneal shunt (VPS) insertion, pathogenesis of hydrocephalus, neonates and infants

## **1. Introduction**

Hydrocephalus may be defined as abnormal accumulation of cerebrospinal fluid (CSF) within the ventricles of the brain, leading to ventricular expansion or enlargement and usually associated with raised intracranial pressure [1, 2]. Hydrocephalus (HCP) is one of the most common associations of myelomeningocele, and it may be overt and present at birth or be latent and develop following the repair of myelomeningocele. It complicates 35–91% of myelomeningocele [3, 4].

It has been reported that the rate of treated hydrocephalus in patients with myelomeningocele varies with the anatomic level of the lesion, 60.7% for sacral, 82.4% for lumbar, and 92.2% for thoracic [4].

Prenatal (fetal) myelomeningocele repair has been shown to significantly reduce the need for insertion of ventriculoperitoneal shunt at 1 year following fetal surgery (prenatal group: 40% vs. postnatal group: 82%) [5].
