脳幹の手術のための第四脳室底モニタリング

Monitoring of the Floor of the 4th Ventricle for Brainstem Surgery

Point

・閂や第四脳室髄条，顔面神経丘といった構造物により，神経核・神経路の位置を推測できる．

・第四脳室底の手術には，神経核や神経路を実際に確認するためのモニタリングが必要である．

・モニタリングの結果のみで術後の神経症状を完全に予測することは困難である．

＊本論文中、［Video］マークのある図につきましては、関連する動画を見ることができます（公開期間：2026年6月まで）。

　The brainstem is densely aggregated with important cranial nerve nuclei and nerve tracts. Surgery in this area is, therefore, risky. Not only anatomical knowledge but also electrophysiological monitoring is essential for brainstem surgery. The facial colliculus, obex, striae medullares, and medial sulcus are important visual anatomical landmarks at the floor of the 4th ventricle. As cranial nerve nuclei and nerve tracts deviate by lesion, it is important to have a firm image of the cranial nerve nuclei and nerve tracts before making an incision in the brainstem. The entry zone into the brainstem is selected where the parenchyma is the thinnest due to the lesions. The suprafacial or infrafacial triangle is often used as an incision site for the floor of the 4th ventricle. In this article, we introduce the electromyographic method of observing the external rectus muscle; orbicularis oculi muscle; orbicularis oris muscle; and tongue; and two cases in which monitoring was used（the pons and medulla cavernoma cases）. By examining surgical indications in this way it may be possible to improve the safety of such operations.