Accessory venous sinus of Hyrtl.

Variations of the intracranial venous sinuses are important to the surgeon during intraoperative procedures and to the clinician during imaging interpretation. We report a male cadaver found to have a rare venous sinus variation. In all likelihood, this sinus corresponded to the rarely reported accessory venous sinus of Hyrtl. The sinus was approximately 5 mm in width and traveled from the sphenoparietal sinus anteriorly to the veins, draining into the foramen spinosum (i.e. the middle meningeal veins) posteriorly. No other variations or obvious pathology were identified intracranially or extracranially. Knowledge of such a venous variation may be of use to the clinician.