Pitfalls in the radiographic diagnosis of stenosis of the internal auditory canal.

The syndrome of stenosis of the internal auditory canal is radiographically suggested by narrowing of the canal on temporal bone tomography or nonfilling on Pantopaque cysternography. The internal auditory canal ends medially at the porous acousticus. In the literature, the radiographs employed to demonstrate this stenosis show the narrowing to be medial to the porous acousticus and therefore extracanalicular. The presumed narrowing is actually in a neurovascular groove on the posterior aspect of the temporal bone. Temporal bone specimens were photographed and tomographed to demonstrate this point. These data suggest that present radiographic criteria for diagnosis of this syndrome are invalid.