[Prevention of facial nerve injury in acoustic neuroma microsurgery].

OBJECTIVE: To summarize and analyse the techniques of avoiding facial nerve injury during acoustic neuroma microsurgery. METHODS: One hundred and eighty patients with large acoustic neuroma (> or =4 cm) and 70 patients with medium acoustic neuroma (2.4-4.0 cm) were diagnosed by MRI/ CT scan before operation and confirmed by postoperative pathologic examination. All of patients were treated by sub-occipital retrosigmoid approach for tumor removal and facial nerve reservation during operation. The relationships among the bone, arachnoid, nerve and vascular anatomy were particularly observed during the operation. After decompression of the tumor, the origination and location of the facial nerve as well as the relationship between the tumor and the facial nerve should be identified. The patients were followed-up from 6 months to 1 year postoperatively and assessed by House-Brackmann facial nerve function grading system. RESULTS: Total tumor resection was achieved in 240 of 250 cases (96%) and subtotal in 10 cases including 1 case died because of cerebellar encephalomalacia after operation. According to the House-Brackmann facial nerve function grading, recovery of normal function (grade I) was achieved in 214 cases (85.6%), grade II in 25 cases (10%), grade III in 5 cases (2.09%) and grade IV in 5 cases (2.09%). CONCLUSION: Microneurosurgical techniques are helpful for total resection of acoustic neuroma and keeping facial nerve anatomic intact.