Surgical treatment of 224 cases of big acoustic neurinoma with special consideration on 76 cases treated microsurgically

　Two hundred and twenty four cases of acoustic neurinoma, bigger than 4 cm in diameter were operated by suboccipital approach in the past 30 years．Among them, 148 cases were operated before the year of 1978 with conventional macrosurgical technic, and 76 cases were operated since 1979 with microsurgical technic．In the former group of cases, the percentage of total removal of tumor was 83.8% and the mortality rate was 5.4%． In the latter group, all tumors were totally removed, there was no mortality, the facial nerve was preserved anatomically in 86.8% of cases and functionally in 71.1%, and the cochlear function was preserved in 21.1% of cases. In 5 cases, the severed ends of the facial nerve were anastomosed intracranially. All of them had their facial nerve function recovered.