| Objectives:To evaluate the long-term facial and hearing function of patients following microsurgical removal of large and huge acoustic neuroma, identify factors that influence these outcomes and investigate ways of preventing never function and improving quality of life.Study design and setting:A retrospective review was performed that included 192 consecutive patients who underwent suboccipital retrosigmoid craniotomy for removal of acoustic neuroma at the Neurosurgical Department, Xiangya hospital by the senior surgeon (Professor Yuan Xianrui, MD&PhD) between January 2002 to November 2009. Patient and tumor characteristics as well as perioperative complications and long-term symptoms are described. House-Brackmann Scale was used preoperatively and in a long-term follow-up i.e. one week,3 months,6 months,9 months,12 months and more than one year after surgery. Pure-tone averages (PTAs) and speech discrimination scores (SDS) were used to document hearing function preoperatively and postoperatively which was classified according to American Academy of Otolaryngology-Head and Neck Surgery (AAO-HNS) criteria. Karnofsky performance status scale (KPS) was used to evaluate the quality of life postoperative. Test for lineartrend and nonparametric test was applied for statistic analysis with PASW Statistics 18.0 (formerly SPSS Statistics).Results:The tumors with an average of 42.4±9.8mm(range 20-65) on sizes were all operated through the suboccipital retrosigmoid approach. Complete resection was achieved in 183(95.3%) of these 192 patients and near-total resection in 7 cases, partial in 1 case, subtotal in 1 case with a mortality of 1.6%. Anatomic preservation of the facial nerve was attained in 96.4% of patients (n=185 of 192). Amone the 106 patient who had at least 1-year follow-up(mean 3.0 years), for all tumor sizes, HB grade 1/2 function was attained in 83%, HB grade 3 in 9.4%, and HB grade 4/5 in 7.5%. Facial function at 1 year after removal of VS was significantly impacted by the size of the tumor. In patients with tumors <30mm, HB grade 1/2 function was attained in 90%(n=9of 10). For tumors≥30mm, HB grade 1/2 function was attained in 82.3%(n=79 of 96). There was statistically significant difference in facial nerve outcome in long-term follow-up when tumor size was considered (p<0.05). 21(12.5%) of overall group with 168 patients maintained usefull hearing preoperatively classified according to AAO-HNS. Cochlear nerve was sure anatomically preserved in 34 cases, and the rest were not sure with the absence of hearing monitoring. Seven patients with an average of 43.6mm (35-60mm) on tumor sizes maintained usefull hearing postoperatively, and two (9.5%) of them are belonged to 21 who had usefull hearing preoperatively. Five of these 7 patients moved from nonfunctional (AAO-HNS class C/D) to functional (AAO-HNS class A/B) categories. There were 132(89.8%) patients in 147 cases with KPS≥80% and 144(98%) in 147 with KPS≥70% we evaluated.Conclusions:Complete removal of large and giant acoustic neuroma may abtained via retrosigmoid approach with facial nerve and possible cochlear nerve preservation.The retrosigmoid is the preferred approach for removal of large and giant acoustic neuroma. Excellent long-term facial function can be expected in the majority of patients who undergo microsurgical removal of vestibular schwannoma via the suboccipital retrosigmoid approach. In our study, we suggest tumor size as a significant prognostic parameter for facial nerve function following vestibular schwannoma surgery. Other parameters such as age, symptom duration, cystic VS and adhesion et al might show correlation with facial nerve outcome when tumor size was considered. The cochlear nerve preservation is extremely low for large vestibular schwannoma after microsurgery, but not impossible. We can not give up on efforts to retain the cochlear nerve regardless the tumor size and preoperative hearing when ever possible.
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