经迷路过路切除听神经瘤常遇到乳突解剖变异，如脑板下垂、前置乙状窦和高位颈静脉球，单独或同时。存在，致乳突腔狭窄，影响手术暴露。Saleh等对600例连续经迷路手术患者中发现210例（3％）乳突腔狭窄，高位颈静脉球144例（24％），前置乙状窦108例（l％）。有关处理方法几乎 Accompanied by labyrinth removal of acoustic neuroma often encountered mastoid anatomical variations, such as the brain ptosis, pre-sigmoid sinus and high jugular bulb, alone or at the same time. Exist, resulting in mastoidosis, affecting surgical exposure. Saleh et al found 210 cases (3%) of mastoid stenosis in 600 consecutive cases of labyrinthine surgery, 144 cases (24%) of high jugular bulb and 108 cases (1%) of anterior sigmoid sinus. The method of treatment is almost