術中急性脳腫脹を来し結果として一塊に摘出された巨大大脳鎌髄膜腫の1例

Huge Falx Meningioma Resected En Bloc Following Acute Brain Swelling: A Case Report

Ⅰ．はじめに

　髄膜腫の手術は①devascularization，②detachment，③decompression/debulking，④dissection/removalの順次遂行を基本操作とするが，巨大腫瘍の場合，内減圧操作（decompression/debulking）なしでは硬膜付着部深部および腫瘍下半分の領域でのdevascularization，detachmentは困難なことも多い．術前栄養血管塞栓術も術中出血量減少に有効と考えられる一方で，それに伴うmorbidity，mortalityは無視できるほど小さなものではなく，実際の出血量減少効果や適応はcontroversialである^1,6)．一方，血管成分に富む巨大髄膜腫摘出に際し術中急性脳腫脹を来した難渋例の報告がある⁴⁾．今回われわれは巨大大脳鎌髄膜腫の手術中，大量出血に続き急性脳腫脹を来し，結果として内減圧操作なしにen blocに摘出された症例を経験したので報告する．

　Surgery of a meningioma is composed of four essential consecutive steps; devascularization, detachment, debulking, and dissection. However, this is not the case with a huge meningioma in which circumferential devascularization and detachment may be difficult to complete before debulking is attempted. We report a case of a 37-year-old female presented headache, memory disturbance, and character change and sustaining a huge falx meningioma, with hypervascular appearance. Intraoperatively her blood pressure decreased to 45/30mmHg due to profuse bleeding caused by“premature debulking”followed by significant brain swelling, which pushed out the tumor from the underlying brain after detachment of the tumor from the falx, and, consequently, yielded en bloc removal like a birth delivery. The histopathological diagnosis was angiomatous meningioma with prominent capillary proliferation without findings of celluar atypia. We thought that relative hyperemia in the brain surrounding the tumor, which was induced by the craniotomy, and acute brain ischemia caused by the intraoperative significant hypotension, might facilitate en bloc removal.

　We should be aware that huge meningiomas may cause intraoperative acute brain swelling as well as significant blood loss. Also we should carefully consider the indication and select proper candidates for presurgical cerebral angiography and tumor embolization because of the inherent risk that is apt to be underestimated.