Jugular bulb diverticula in medial petrous bone.

Upward extension or diverticulum of the jugular bulb is rare. Most often, it protrudes into the middle ear. Three patients are reported in whom direct superior extension from the medial portion of the jugular bulb resulted in a defect in the medial part of the petrous bone. In this position, a jugular bulb diverticulum relates directly to the posterior wall of the internal auditory canal. The distinctive radiographic characteristics of this entity obviate unnecessary investigation and surgery. Encroachment on the internal auditory canal may possibly contribute to neurosensory hearing deficit.