Diploic vein as a newly treatable cause of pulsatile tinnitus: A case report.

BACKGROUND Pulsatile tinnitus (PT) is an annoying sound that can be eliminated with targeted treatment of the cause. However, the causes of PT have not been fully elucidated. CASE SUMMARY A 38-year-old woman with right-sided objective PT underwent preoperative computed tomography arteriography and venography (CTA/V). A 3.8 mm vine diploic vein (DV), which passed through the mastoid air cells posteriorly in a dehiscent canal and was continuous with the transverse-sigmoid sinus, was thought to be the causative finding. Four-dimensional flow magnetic resonance (4D flow MR) imaging showed that the blood in the DV flowed toward the transverse-sigmoid sinus. The closer the blood was to the transverse-sigmoid sinus, the higher the velocity. No vortex or turbulence was found in the DV or adjacent transverse sinus. The sound was eliminated immediately after ligation of the DV with no recurrence during a three-month follow-up. No flow signal of the DV was noted on postoperative 4D flow MR. CONCLUSION A DV may be a treatable cause of PT. CTA/V and 4D flow MR could be utilized to determine the morphological and hemodynamic characteristics of the DV.