Core Terms & Classification
Triventricular hydrocephalus
Triventricular hydrocephalus is enlargement of the two lateral ventricles and the third ventricle, typically due to a blockage at the cerebral aqueduct.
In short: Triventricular hydrocephalus
- Three ventricles (both lateral and the third) are enlarged.
- The fourth ventricle is typically normal in size.
- It points to a blockage at the cerebral aqueduct.
- It is often well suited to treatment with ETV.
What it is
Triventricular hydrocephalus is enlargement of three ventricles — both lateral ventricles and the third ventricle — while the fourth ventricle remains normal. The pattern reflects where CSF is backing up.
Understanding Triventricular hydrocephalus
Because the lateral and third ventricles are enlarged but the fourth is not, this pattern points to a blockage at the cerebral aqueduct (the narrow channel between the third and fourth ventricles), known as aqueductal stenosis. Fluid accumulates upstream of the aqueduct, enlarging the three ventricles above it. This pattern is often a good candidate for endoscopic third ventriculostomy (ETV), which creates a new outlet from the third ventricle to bypass the aqueductal blockage.
Why it matters
Understanding triventricular hydrocephalus helps families see how the pattern of enlarged ventricles points to the location of the blockage, and why this pattern is often treatable with ETV rather than a shunt.
Common questions
Which ventricles are enlarged?
Both lateral ventricles and the third ventricle.
What does the pattern suggest?
A blockage at the cerebral aqueduct.
How is it often treated?
Frequently with ETV.
Bottom line
Triventricular hydrocephalus enlarges the lateral and third ventricles, pointing to an aqueductal blockage often treatable with ETV.
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