Two cases of petrosquamosal sinus in the temporal bone presented as perioperative finding.

The petrosquamosal (PSS) is an embryonic emissary vein of the temporal bone in humans and connects the intra- and extracranial venous networks. Few reports in the recent literature provide detailed descriptions of PSSs that are found before or during surgeries. We report the presence of PSS in two patients with chronic otitis media. An abnormal vessel was found originating from the sigmoid sinus of each patient. The vessels coursed anteroinferiorly over the superior portion of the temporal bone and terminated near the posterior part of the temporomandibular joint. The clinical significance of PSS and a brief literature review are presented.