錐体静脈の術前評価における3次元画像の有用性：4例報告

Three-dimensional Images of Petrosal Veins for Preoperative Evaluation: Four Case Reports

Ⅰ．はじめに

　三叉神経痛や脳腫瘍などに対する上部小脳橋角部の手術では，錐体静脈（petrosal vein：PV）の存在が手術の妨げになる．また，その分枝の1つであるvein of the cerebellopontine fissure（VCPF）を含むPVの切断は，小脳の出血性梗塞など重大な合併症を起こし得ることが知られており，極力温存するよう努力すべきである^3,4,5)．他方，これらのPVをうまく処理できれば，術中のランドマークとなり得る．したがって，PVの術前評価は当部位の手術において非常に重要であり，われわれは術前に3次元（three dimension：3D）画像検査を行っている．4症例を提示し，その検査の有用性について報告する．

　Background: In the surgeries of the upper part of the cerebellopontine angle (CPA),the petrosal vein (PV) is an obstacle,and the resection of the PV sometimes causes postoperative complications such as cerebellar hemorrhagic infarction. On the other hand,it can be an anatomical landmark during the surgery. We have used three-dimensional (3D) CT images for preoperative evaluation. We,herein,report 4 cases of CPA lesions.

　Method: The PV was imaged with neighboring structures using CT and a workstation. We paid attention especially to the vein of the cerebellopontine fissure (VCPF).

　Result: The four cases include one case of trigeminal neuralgia, two meningiomas and one case of acoustic schwannoma. 3D CT images showed (1) the anatomical formation such as course of the PV, (2) relationship to the neighboring structures of the tumors, (3) expectation of complications after sacrificing the PV. By observing the preoperative 3D CT images, we were able to plan safety operative approaches and procedures.

　Conclusion: 3D CT images of the PV are very useful for preoperative evaluation of surgery in CPA lesions.