Surgery for parasagittal meningiomas

Abstract

Parasagittal meningiomas generally originate in the lateral wall of the superior sagittal sinus and the adjacent convexity dura, so that they fill the space between the convexity dura, the lateral wall of the superior sagittal sinus and the falx. They account for 21 to 31% of all intracranial meningiomas in surgical series. Clinical symptoms and signs depend upon the location of the tumors. Anterior third parasagittal tumors most commonly cause headache, seizure, and later on, changes in mental status, and can sometimes become huge in size. Middle third tumors cause seizures and focal weakness. Unilateral motor findings are most common and are usually greater in the leg than in the arm or face. Posterior third tumors most commonly causes headache and visual changes. In surgical resection, it is very important to define the arachnoid plane around the tumor, and to be careful to preserve the adjacent parasagittal draining veins. The authors prefer first to detach the tumor from the main feeding arteries which exist on the falx or convexity dura and debulk the center of the tumor centrally to reduce the size, allowing development of the arachnoid planes and tumor margins. Small pial branches going directly to the tumor from the anterior or middle cerebral arteries are coagulated and derided. Eventually, a globular portion of the tumor is removed. When the parasagittal sinus or the adjacent parasagittal draining veins are invaded by the tumor, but not occluded, the authors prefer simply to reset the globular portion of the tumor and allow recurrent tumor to slowly occlude the sinus or veins, allowing venous collateral circulation develop. The tumor can be resected when the sinus and veins are occluded at recurrence. Recently, we have begun considering stereotactic radiosurgery as an option in the treatment for these tumors.