5 % are higher than the superior edge of endolymphatic sac . 3 . by retrolabyrinthine approach , rectangle incision of duramater got 116 . 80 mm2 surgery scope 颈静脉球顶高于后半规管下缘者占22 . 5 ；高于内淋巴囊上缘者占5 ；高于面神经锥段者占12 . 5 。
2.
Super - posterior semicircular canal resection s scope is wider than posterior semicircular canal resection and could treat internal acoustic meats lesions too . conclusion : we get the scope of the two different incisions of duramater . study the effect of the sigmoid sinus , jugular bulb and cerebellopontine angle area to retrolabyrinthine approach surgery 后、上半规管切除在外半规管以下所得范围同后半规管切除相似，在外半规管平面以上可以有一较大的暴露范围，可以一直暴露到内听道口，甚至可以暴露内听道的全程，因此可以在直视下处理内听道内的病变。
