Interhemispheric Approachにおける静脈温存と脳圧排軽減のための工夫—前交通動脈瘤例における検討

Technical Tactics to Preserve Cortical Venous Drainage in Interhemispheric Approach for Anterior Communicating Artery Aneurysms

I．はじめに

　前交通動脈瘤（Acom）に対するInterhemispheric approachは，pterional approachと並んで標準的なアプローチであり，高位で後方向きや大脳間裂に大きな血腫がある場合，クモ膜下腔の血腫除去を広範囲に行う際などで広い視野が得られる特徴がある．しかし，時に前頭葉のbridging veinの切断や，interdigitationの強い大脳間裂を分けて前頭葉を圧排する際に，静脈還流障害による脳内血腫や脳挫傷が生じる場合が少なくない．こうした合併症の発生を予防するために，われわれは，両側前頭小開頭後，大脳鎌をその最前端で工夫して切断し，前頭葉が後方へ落ち込むことを利用して，bridging veinを可及的に温存すること，また前頭葉の最前端部のみで大脳間裂を分けて前頭蓋底にそってアプローチし，半球間裂の圧排を少なくすることを試みた．

　これらの症例の手術前後の臨床症状，血管撮影上の静脈還流のパターンおよび術後のcomputed tomography（CT）所見と手術所見を対比して検討した．

The interhemispheric approach has been selected for clipping of the anterior communicating artery aneurysm located high above the sphenoidal plate, and in a pos-terior direction. However, this approach is sometimes complicated with postoperative hemorrhagic infarction due to excess brain retraction combined with damages of the cortical bridging veins.

We have devised a modification in this approach to eli-minate these complications. Our newly devised methods include the following; 1) Small bifrontal craniotomy performed, 2) Continuous ventricular drainage per-formed to minimize the effect of compression by the spa-tula during resection of interhemispheric fissure, 3) Bifrontal dural incision made along the frontal skull base, 4) Mobilization of the major cortical vein in the operated field, if necessary, by resection of the overlying arach-noid membrane with or without sacrificing its small tri-butaries, 5) Gradual dissection of the olfactory nerves according to the process of operation.

We analysed the incidence of operative complications in thirteen consecutive cases with this approach. Major frontal ascending veins were carefully preserved in all cases. None showed hemorrhagic infarction, regardless of the cortical venous drainage patterns. The degree of smell preserved in 10% of the examined 11 cases was more than unilateral.

In conclusion, this method is useful for the elimination of perioperative complications even in the acute stage of subarachnoid hemorrhage.