Pseudoaneurysm of the petrous internal carotid artery after skull base infection and prevertebral abscess drainage.

A 37-year-old woman with a skull base infection sustained massive oropharyngeal bleeding after incisional nasopharyngeal biopsy and drainage of a prevertebral abscess. A pseudoaneurysm originating at the petrous portion of the internal carotid artery was initially misinterpreted on MR images as typical postoperative change within a resolving abscess cavity. Follow-up MR imaging and conventional angiography ultimately disclosed the pseudoaneurysm.