Analysis of venous drainage from sylvian veins in clinoidal meningiomas.

OBJECTIVE: To categorize clinoidal meningiomas according to their venous drainage patterns, and use each category as a guideline to establish an appropriate surgical strategy.
METHODS: We performed a retrospective analysis of 22 consecutive surgically treated patients with clinoidal meningioma who underwent preoperative digital subtraction angiography to examine the characteristics of the venous drainage system. These patients were categorized into: 1) cortical type in which the sylvian vein did not drain medially but drained to cortical veins, 2) sphenobasal type in which the sylvian vein drained into the pterygoid plexus, or 3) cavernous type in which the sylvian vein drained into the cavernous sinus directly through the sphenoparietal sinus. We tailored the surgical strategy to preserve these draining veins.
RESULTS: Preoperative angiographic evaluation demonstrated 14 patients (63.6%) with cortical type, 6 patients (27.3%) with sphenobasal type, and 2 patients (9.1%) with the cavernous type. In most cases, no restriction from the venous structure was observed because the sylvian vein belonged to the cortical type. However, in the case of the sphenobasal or sphenoparietal type, the surgical strategy seemed to be tailored to preserve the venous drainage system.
CONCLUSIONS: The surgical risk from venous complication in the treatment of clinoidal meningiomas appears to be low; however, there are likely to be patients that require a tailored surgical approach to avoid venous complications. Detailed preoperative assessment of anatomic structure and consideration of the optimal surgical strategy are critical to improve treatment outcomes.