Aqueductal stenosis

Joseph R Siebert PhD (Dr. Siebert of the University of Washington has no relevant financial relationships to disclose.)
Harvey B Sarnat MD FRCPC MS, editor. (

Dr. Sarnat of the University of Calgary has no relevant financial relationships to disclose.

Originally released November 16, 2018; last updated September 5, 2020; expires September 5, 2023


Narrowing of the cerebral aqueduct of Sylvius is termed aqueductal stenosis. The aqueduct joins the third and fourth cerebral ventricles and allows passage of cerebrospinal fluid between the two chambers. When narrowed, CSF accumulates, dilating the upstream ventricles and causing ventriculomegaly. The consequences and treatment of this condition are discussed in the following paragraphs.

Key points

Stenosis of the cerebral aqueduct of Sylvius:


• may be congenital (and hereditary) or acquired.


• restricts the circulation of CSF.


• results in dilatation of the lateral and third ventricles often with increased intracranial pressure.


• may result in thinning or other damage to the cerebral cortex.


• may be debilitating or even fatal.

Historical note and terminology

Hydrocephalus has been depicted in the descriptive literature of the seventeenth and eighteenth centuries and has presumably occurred throughout human history.

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