Aqueductal Web Causing Obstructive Hydrocephalus in a 50-Year-Old Patient

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In this case presentation, we review the imaging findings of a 50-year-old male presenting with balance issues, visual disturbances, and general fatigue. While aqueductal stenosis is often associated with pediatric populations, adult-onset presentation due to an ependymal web is a critical diagnostic entity to recognize.

Check out the full breakdown and see the high-resolution sequences in the video below:


Key Imaging Findings

  • Ventriculomegaly: The ventricular system is widened supratentorially, with an Evans' index of 0.36. The temporal horns and cerebral sulci remain within normal limits.

  • Secondary Signs of Hydrocephalus: Notable upward expansion of the corpus callosum and very faint transependymal leakage (interstitial edema).

  • The Web: High-resolution multiplanar reconstruction (MPR) and sagittal FLAIR sequences reveal a thin membrane localized to the lower one-third of the aqueduct.

  • Caliber Mismatch: The aqueduct measures approximately 4 mm at the level of the superior colliculus, tapering abruptly to just 1 mm at the web before returning to normal caliber.

Main Teaching Points

  1. Embryological Origin: An aqueductal web is a developmental anomaly occurring at the junction between the mesencephalon (midbrain) and metencephalon (hindbrain). This transition zone is a classic location for ependymal webs to manifest.

  2. Subtle Presentation: Unlike classic aqueductal stenosis, you may not always see a prominent "gaping" upper aqueduct, and the structural changes can be remarkably subtle. Dedicated thin-slice 3D T2 or sagittal FLAIR sequences are essential for definitive visualization.

  3. Surgical Anatomy: Management typically involves Endoscopic Third Ventriculostomy (ETV). Surgeons access the floor of the third ventricle (often visually mimicking an "anteater" profile on sagittal view) to create an opening into the prepontine cistern, bypassing the obstruction.

For more radiological case reviews, imaging workflows, and clinical discussions, explore the archives here on the Radiant Pixels blog and don't forget to subscribe to the YouTube channel for regular video updates. 

Check also my previous case that is very simmilar showing Aqueduct Stenosis. 

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