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  • Updated 09.08.2023
  • Released 11.16.2018
  • Expires For CME 09.08.2026

Aqueductal stenosis



Narrowing of the cerebral aqueduct of Sylvius is termed aqueductal stenosis. Cerebrospinal fluid flow is restricted but still occurs. Aqueductal atresia, by contrast, is a total obliteration of the cerebral aqueduct, leaving only a few ependymal clusters and rosettes in its place that enable no CSF flow. The aqueduct is the conduit between the third and fourth cerebral ventricles. When narrowed, CSF accumulation dilates the upstream lateral and third ventricles and cause ventriculomegaly that often can be detected in fetal ultrasound images in the second trimester. The consequences and treatment of this condition are discussed in this article.

Key points

Stenosis of the cerebral aqueduct of Sylvius:

• May be congenital (genetic origin) or acquired.

• May be isolated; associated with other brain malformations, vascular anomalies, or genetic syndromes; or secondary to acquired lesions that infiltrate, compress, or cause inflammation and gliosis in periaqueductal tissue.

• Posthemorrhagic hydrocephalus may be due to intra-aqueductal blockage by blood descending from the lateral and third ventricles in intraventricular hemorrhage in the perinatal period.

• Restricts the circulation of CSF, resulting in dilatation of the lateral and third ventricles increased intraventricular pressure.

• May result in potentially reversible thinning of the cerebral mantle and corpus callosum.

• May be progressive, debilitating, or even fatal.

• Does not cause epilepsy.

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. The most frequent cause of hydrocephalus in the perinatal period is isolated aqueductal stenosis.

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