[Treatment of skull base meningioma encasing the main cerebral artery]

We reviewed the clinical findings, the surgical problems and results in fifteen operated cases of skull base meningioma encasing the main cerebral arteries. The fifteen cases of meningiomas are summarized as follows; The patients' age ranged from 18 to 76 years old with an average age of 48 years old. Thirteen were in female and two in males. Of 15 cases, four cases were sphenoid ridge meningiomas (all clinoidal types), three cases were planum sphenoidale, two cases were tuberculum sellae, olfactory groove and cerebellar tentorium, one case was a cerebello-pontine angle and foramen magnum meningioma. Twelve cases (80%) had a large tumor of 50mm in maximum diameter. Major advances in imaging modalities, especially magnetic resonance imaging (MRI), have enabled precise preoperative information about vascular encasement and location of the encased vessels within the tumor. Preoperative tumor embolization was performed in 2 patients, STA-MCA anastomosis was performed in one patient with severe stenosis of the internal carotid artery encased in the tumor. In 5 cases with the presence of interfacing arachnoid membranes between the tumor and cerebral vessels, the tumor was totally removed. In the 10 patients without interfacing arachnoid membranes, total removal was achieved in 4 of the 10 patients by the sacrifice of the encased artery and in one patient injuring the arterial wall consequently. In the remaining 5 patients, the tumor could not be removed totally. One patient showed a recurrence on follow-up ranging from 0.5 to 13 years. In conclusion, greater difficulty with dissection of such tumors was encountered in patients who did not have an arachnoid plane between the encased artery and the tumor. In those cases, to avoid the devastating sequelae injuring the encased cerebral vessels and its surrounding perforators, we considered that total removal should not be carried out.