Radiology, Vol 154, 667-670, Copyright © 1985 by Radiological Society of North America
The cerebellopontine angle and internal auditory canal: neurovascular anatomy on gas CT cisternograms
CR Bird, AN Hasso, BP Drayer, DB Hinshaw Jr and JR Thompson
We reviewed 103 normal gas CT cisternograms to delineate the appearance of
normal neurovascular structures in the cerebellopontine angle (CPA) and
internal auditory canal (IAC). Cranial nerves VII and VIII were identified
in the CPA in 97% of cases, either separately (53%) or as a bundle (44%).
Intracanalicular branches of the VIIIth cranial nerve were identified in
20% of cases, and cranial nerve V was visualized in the CPA in 14%. The
characteristic vascular loop, usually the anterior inferior cerebellar
artery, was visible in 35% of cases, and, in 22% of visualized cases, was
in an intracanalicular location. The internal auditory artery was
questionably visualized in one case. In 10% of cases, greater than 66% of
the IAC was occupied by the neurovascular bundle. Familiarity with the
normal anatomy and variants seen on gas CT cisternograms is necessary to
prevent false-positive interpretations.
