Guidelines for the ligation of the sigmoid or transverse sinus during large petroclival meningioma surgery

The authors present guidelines for the ligation of the transverse or sigmoid sinus during the surgical removal of petroclival meningiomas. The medical records and venograms of 14 patients with a petroclival meningioma requiring transverse or sigmoid sinus ligation treated in the Department of Neurosurgery, Seoul National University Hospital between 1986 and 1999 were reviewed. All patients successfully received a sinus trial clamping during the operation. The drainage pattern of the confluens of Herophili was classified into four types: Type A, confluens and equal on both transverse sinuses; Type B, confluens and nondominant transverse sinus on the tumor side; Type C, confluens and dominant transverse sinus on the tumor side; and Type D, unilateral transverse sinus only. Of the 14 cases, four were Type A, five were Type B, and two were Type C. There was no brain swelling after intraoperative test clamping of the sinus for more than 30 minutes. None of the cases developed postoperative complications related to the sinus ligation. Patients with Type A, B, or C drainage patterns were ideal candidates for sinus ligation, especially transverse sinus ligation, if the test clamping proved to be safe. The sinus was cut proximal to the superior petrosal sinus, distal to the vein of Labbé.