Aqueductal stenosis is a congenital or acquired narrowing of the aqueduct of Sylvius — the narrow channel connecting the third and fourth ventricles of the brain. When this passage is blocked, cerebrospinal fluid (CSF) cannot circulate properly, causing obstructive (non-communicating) hydrocephalus. This leads to ventricular enlargement, increased intracranial pressure, and potential harm to brain development if untreated. Early recognition and surgical management restore CSF flow and prevent long-term neurological damage.
Symptoms
The severity and timing of symptoms depend on whether the condition is present at birth or develops later in childhood or adulthood.
In Infants
- Rapid increase in head size
- Bulging fontanelle and separated sutures
- Downward deviation of the eyes (“sunset sign”)
- Irritability, vomiting, or poor feeding
- Delayed motor or cognitive milestones
In Older Children or Adults
- Headache, nausea, and visual disturbances
- Gait instability or clumsiness
- Urinary urgency or incontinence
- Lethargy or memory difficulty
- Signs of raised intracranial pressure
Causes
- Congenital narrowing due to developmental defect of the aqueduct
- Post-infectious inflammation (after meningitis)
- Intraventricular hemorrhage in premature infants
- Tumors or cysts compressing the aqueduct
- Genetic or X-linked aqueductal stenosis, which can run in families
Diagnosis
Diagnosis begins with MRI of the brain, which clearly visualizes the ventricular system and identifies the site of blockage in the aqueduct. Cine phase-contrast MRI is particularly useful for assessing CSF flow dynamics. In infants, cranial ultrasound can detect ventricular enlargement before fontanelle closure. CT scans may be used in emergencies to confirm hydrocephalus. Ophthalmological evaluation helps detect papilledema (optic nerve swelling) from increased intracranial pressure.
Treatment Options
- Endoscopic Third Ventriculostomy (ETV): This is the preferred treatment for aqueductal stenosis. Using a small endoscope, the surgeon creates a tiny opening in the floor of the third ventricle, allowing CSF to bypass the blocked aqueduct and flow directly to the brain’s basal cisterns. ETV restores natural CSF circulation without the need for an implanted shunt system. Success rates are high, especially in older infants and children with isolated obstruction.
- Ventriculoperitoneal (VP) Shunt Surgery: If ETV is not feasible (especially in very young infants or complex anatomical cases), a VP shunt is placed to drain excess CSF from the ventricles to the abdominal cavity. Modern programmable valves allow precise control of drainage and long-term adjustability. Shunt systems remain reliable and safe when regular follow-up is maintained.
- Management of Associated Conditions: If the stenosis results from infection, bleeding, or tumor compression, treating the underlying cause is essential. In some genetic cases, counseling and family screening may be recommended.
Recovery & Follow-Up
After ETV or shunt surgery, children are usually discharged within 2–5 days. Parents are taught to recognize warning signs such as vomiting, drowsiness, irritability, or gaze deviation, which may indicate recurrence or shunt malfunction. Routine MRI follow-up confirms the patency of the ETV opening and stable ventricular size. Most children, once treated early, achieve normal neurological and cognitive development.
When to See a Pediatric Neurosurgeon
If your child develops rapid head growth, vomiting, delayed milestones, or eye movement abnormalities, seek prompt evaluation. Early surgical management of aqueductal stenosis prevents hydrocephalus-related complications and supports healthy brain growth.