Facial Nerve Protection Evaluation During The Operation Of Giant Acoustic Neuroma Resection By Retrosigmoid Approach And Analysis Of Prognositic Factors

ObjectiveTo investigate the effect of nerve electrophysiological monitoring on facial nerve anatomy and function preservation in giant acoustic neuroma resection via retrosigmoid approach. Postoperative follow-up of 1 week to 6 months after the operation, factors affecting facial nerve function were analyzed. Methods47 cases of giant acoustic neuroma surgery treated in the Second Clinical College of Zhengzhou University from September 2011 to September 2015 were studied. According to whether or not the neural electrophysiological monitoring was applied, 47 cases were divided into monitoring group(26 cases) and non monitoring group(21 cases), the rate of surgical resection, facial nerve anatomy and function of the two groups were compared and analyzed. According to the House-Brackmann(H-B) facial nerve function classification standard as the evaluation index of facial nerve function, facial nerve functions of all patients were followed up regularly by means of return visit and telephone as supplementary means. The correlation between facial nerve function 6 months after operation and the related factors such as patients age, tumor size, tumor texture, tumor edema, duration of preoperative symptoms, facial nerve function 1 week after operation was analyzed using statistical methods, assuming P<0.05 difference has statistical significance. ResultsIn the monitoring group(n=26), the tumor diameter of 3~ 4cm are 16 cases, > 4cm10 are cases, solid tumors are 15 cases, cystic tumors are 11 cases; In the non monitoring group(n=21), the tumor diameter of 3 ~ 4cm are 13 cases, > 4cm are 8 cases, solid tumor are 11 cases, cystic tumors are 10 cases. The operative approach was all via retrosigmoid approach. Total resection rate was 73.1%(19/26) in the monitoring group and 76.2%(16/21) in the non monitoring group, there was no significant difference between the two groups(P>0.05). The rate of facial nerve preservation was 100%(26/26) in the monitoring group and 81%(17/21) in the non monitoring group, the difference was statistically significant(P < 0.05). Facial nerve function 6 months after operation in monitoring group: 12 cases of grade I, 6 cases of grade II, 6 cases of grade III, 2 cases of grade IV; In non monitoring group: 4 cases of grade I, 6 cases of grade II, 4 cases of grade III, 2 cases of grade IV, 1 case of grade V and 4 cases of grade VI; According to the analysis of the nerve function 6 months after operation in the two groups, the difference between the two groups has statistical significance(P<0.05). In these related factors, tumor size and tumor texture had correlation with facial nerve function 6 months after operation in the monitoring group(single factor Logistic regression analysis, P<0.05), and tumor size was a key factor(multivariate Logistic regression analysis, P<0.05). Conclusion1. Giant acoustic neuroma resection via retrosigmoid approach is safe and effective. Electrophysiological monitoring has important significance in facial nerve anatomy and function preservation.2. Tumor size, tumor texture had correlation with postoperative long-term facial nerve function. And the tumor size is significant risk factor for long-term facial nerve function in postoperative, it can be used to predict postoperative facial nerve function, which means the greater the preoperative tumor, the worse the neurological function.