Persistent petrosquamosal sinus in adults: qualitative imaging evaluation on high-resolution CT venography.

Background: The persistent petrosquamosal sinus (PSS) is usually overlooked before or during otological surgeries, which may cause misdiagnosis or iatrogenic bleedings. Imaging characteristics have not been well summarized for PSS, especially for large consecutive cases.
Purpose: To analyze the characteristics of PSS on high-resolution CT venography (HRCTV) in order to improve imaging diagnostic accuracy as well as to assist clinical management.
Material and Methods: Five hundred and thirty-two consecutive patients with pulsatile tinnitus who underwent CT angiography and venography examinations in the last 4 years were reviewed. Thirty patients with PSS in 39 temporal bones (TBs) were identified by two radiologists' consensus. The characteristics of PSS were analyzed according to its embryological variations. Different types of PSS were divided according to the origin and course, respectively.
Results: The average diameter of the PSS was 1.4 mm. Twenty-nine TBs (74%) had PSS origin from the dorsolateral surface of the transverse sinus before its junction with the superior petrosal sinus (Position A); three TBs (8%) had PSS origin from the ventroinferior surface of the transverse sinus after or before the junction (Position B or C); seven TBs (18%) had PSS without definite origin (Position D). Eighteen TBs (46%) had PSS course in a lateral bony canal/groove (lateral canal type); 15 TBs (38%) had PSS course in petrosquamosal fissure (PSF) (PSF type); six TBs (15%) had PSS course in both (lateral canal/PSF type). For other imaging findings, a branch entering the cranial part of PSS was identified in 10 TBs (26%); a vascular mass was formed in five TBs (13%); focal defect of bony wall was observed in seven TBs (18%). A postglenoid foramen (PGF) was detected in 25 TBs (64%).
Conclusion: HRCTV can mostly identify the characteristics of PSS similar to its anatomic findings and the optimal imaging technique has the potential to improve its clinical management.