The purpose of this study is to study whether infants with triventricular hydrocephalus (TVH) have a better long-term outcome at 5 years when they are treated with a new procedure, endoscopic third ventriculostomy (ETV), than infants treated with the more traditional treatment, insertion of a cerebrospinal fluid (CSF) shunt.

TVH is a relatively uncommon condition in infants, in which CSF accumulates in the brain's ventricles due to a blockage in outflow at the level of cerebral aqueduct. This can cause increased intracranial pressure, with adverse effect on brain development. The causes of this include congenital aqueductal stensois or acquired aqueductal stenosis from previous brain hemorrhage or infection.

TVH is currently treated through one of the following two approaches:

• Extra-cranial CSF diversion through ventricular shunts. Extra-cranial shunting has been the standard approach over the past few decades, since functional shunts were first developed and inserted successfully.
• Intra-cranial internal CSF diversion using endoscopic techniques. The principles of internal diversion were clear from the time neurosurgeons first understood the nature of hydrocephalus. However, internal diversion was never really practical or successful on a large scale until the more recent development of neuroendoscopy. There is currently a revived interest in diversionary hydrocephalus treatment through neuroendoscopic surgical techniques, with the primary focus on endoscopic third ventriculostomy (ETV).

Inclusion Criteria:

• Symptomatic TVH requiring treatment.
• No previous treatment for TVH
• Under 24 months of age at time of surgery
• Full-term pregnancy (>36 weeks)
• Mandatory pre-operative MRI that includes mid-sagittal T1 & T2 scans which show: Tri-ventricular pattern of hydrocephalus; proof of no flow through aqueduct; presence of CSF collection over the convexity and/or inter-hemispheric fissure is acceptable; configuration of third ventricle floor could vary; deformed tectal plate is acceptable; posterior fossa fluid collections may be included as long as: aqueduct is closed; vermis preserved (complete Dandy Walker Syndrome excluded); questionable flow in aqueduct acceptable as long as TVH exists
• History or suggestion of intra-ventricular bleed (intra-uterine or post-natal) or intracranial infection qualifies (excluding intraventricular hemorrhage of prematurity).
• Ability to participate in followup for at least 5 years

Exclusion Criteria:

• Open Spina Bifida
• Complete Dandy Walker syndrome (vermian agenesis / dysgenesis)
• Prematurity
• Perinatal asphyxia
• Severe dysmorphic anatomical features or known chromos (e.g. agenesis of corpus callosum, heterotopias, large cysts)
• intracranial tumor