Causes & Risk Factors
Aqueductal stenosis
Aqueductal stenosis is a narrowing of the cerebral aqueduct that blocks cerebrospinal fluid flow, a common cause of obstructive hydrocephalus.
In short: Aqueductal stenosis
- It is a narrowing of the channel between the third and fourth ventricles.
- It is a common cause of congenital obstructive hydrocephalus.
- It produces a triventricular pattern of enlarged ventricles.
- It is often well suited to treatment with ETV.
What it is
Aqueductal stenosis is a narrowing (stenosis) of the cerebral aqueduct, the thin channel carrying CSF from the third to the fourth ventricle. The narrowing obstructs CSF flow, causing fluid to back up.
Understanding Aqueductal stenosis
Because the aqueduct is the narrowest point in the ventricular system, narrowing here readily blocks CSF flow, enlarging the lateral and third ventricles while the fourth stays normal (the triventricular pattern). Aqueductal stenosis is one of the most common causes of congenital obstructive hydrocephalus and can also be acquired (for example, from a tumor or scarring). It can be congenital and isolated or part of a genetic condition such as X-linked hydrocephalus. Because the blockage is discrete, aqueductal stenosis is frequently treated with endoscopic third ventriculostomy (ETV), which bypasses the aqueduct.
Why it matters
Understanding aqueductal stenosis helps families see how narrowing of a key channel causes a recognizable pattern of hydrocephalus, and why this type is often treatable by bypassing the blockage with ETV rather than a shunt.
Common questions
What is aqueductal stenosis?
A narrowing of the cerebral aqueduct that blocks CSF flow.
Is it a common cause?
Yes — a common cause of congenital obstructive hydrocephalus.
How is it often treated?
Frequently with ETV, which bypasses the aqueduct.
Bottom line
Aqueductal stenosis is a narrowing of the cerebral aqueduct, a common cause of obstructive hydrocephalus often treated with ETV.
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