The focus of [[vestibular schwannoma surgery]] has shifted from low mortality and tumor resection to retention of neurological function. [[Hearing preservation]] is another point in addition to facial nerve function preservation. Hearing preservation rates overall ranged from 2% to 93% in recent studies. Characteristics such as approach, pre-operative neurological function, tumor size, nerve of origin and [[fundal fluid]] of the internal auditory canal have been reported as possible influencing factors
((Tan HY, Wang ZY, Wu H. [Factors of hearing preservation in acoustic neuroma
surgery]. Zhonghua Er Bi Yan Hou Tou Jing Wai Ke Za Zhi. 2017 Oct
7;52(10):783-786. doi: 10.3760/cma.j.issn.1673-0860.2017.10.016. Chinese. PubMed 
PMID: 29050101.
)).

The presence of fluid in the [[fundus]] on preoperative MRI is predictive of hearing outcomes and should be used in counseling patients who are considering hearing preservation surgery via a middle cranial fossa approach for the treatment of isolated vestibular schwannoma
((Goddard JC, Schwartz MS, Friedman RA. Fundal fluid as a predictor of hearing
preservation in the middle cranial fossa approach for vestibular schwannoma. Otol
Neurotol. 2010 Sep;31(7):1128-34. doi: 10.1097/MAO.0b013e3181e8fc3f. PubMed PMID:
20657334.
)).