Facial Nerve Function And Hearing Preservation After Resections Of Large Acoustic Neuromas Using Facial Nerve Monitoring

Objective:study long-term facial function and the continuous change and hearing preservation after large acoustic neruomas resections and identify factors influence these outcomes.Methods:A total of 127 cases acoustic neuromas were microsurgically removed via retrosigmoid approach using electromyography monitoring at the xiangya hospital Neurosurgical Department from 2002.1-2008.4 by the senior surgeon(professor yuanxianrui, MD&PHD).A retrospectively reviewed was performed.Outpatient clinical follow-up every 3 to 6 months includes evaluation of facial nerve function and PTA.The facial nerve function was assessed by using House-Brackmann facial nerve grading system.The hearing function was evaluated by New Hannover Classification and Criteria of Gardner, Shelton,and House.Results:The tumor size was 43.0±10.2 mm.Of 125 cases of complete removal and 2 cases of deliberately partial removal,the facial nerve was anatomically preserved in 126 of 127 cases(98.2%).and preservation is supported by special electrophysiological monitoring.All the patients were treated in a routine follow-up program every 3 to 6 months as possible.According to House-Brackmann facial nerve grading system,postoperative immediate,1 week,3 months,6months,9 months and 1 year or more,the percentage of HBⅠ-Ⅱwas 90.2%, 52.5%,42.9%,48.8%,63.5%and 85.5%,respectively.Facial nerve function was the best at the postoperative immediate and in one year or more. During this time,facial nerve function deteriorated rapidly in the first 3 months postoperatively,and recovery was found in the 6^thmonth.The non-parameter analysis and test for linear trend show that tumor size (p＜0.005)and early facial nerve function(p＜0.0001)correlate with the facial nerve function at 1 year or more postoperatively.Patient age,sex, symptom duration,cystic change,and preoperative hydrocephalus do not influence facial nerve function.According to the New Hannover Classification and Criteria of Gardner,Shelton,and House,hearing was preserved postoperatively(H1-H3)in the 11 of 41(26.8%).Conclusion:Resection of acoustic neuroma via retrosigmoid approach using electromyography monitoring is a safe and effective method.The study firstly finds the dynamic curve of facial nerve function after resection of large acoustic neuroma.In most cases,the onset of recovery occurs in 6^thmonths.Of 85.5%cases have excellent facial nerve function(HBⅠ-Ⅱ)at 1 year or more postoperatively.The long-term facial nerve function correlate with early facial nerve function(p＜0.0001) and tumor size(p＜0.005).