Analysis Of Clinical Therapeutic Effects Of Microsurgical Treatment For Different Size Of Vestibular Schwannomas Via Retrosigmoid Approach

Objectives:To analyze the outcome of microsurgery and explored the related factors in a consecutive series of patients with different size of vestibular schwannomas(VSs)Methods:500patients who had underwent VSs operations at neurosurgical department of Xiang Ya Hospital from2002to2013by the same surgeon(Professor Xianrui Yuan,MD&PHD)were included in this retrospective study. In all cases the retrosigmoid approach and intraoperative neurophysiological monitoring were used. We divide all cases into three groups based on extrameatal diameter, including VSs<30mm(Group A),30-39mm(Group B)and≥40mm(Group C). The number of three groups is respectively74,158and268. Outcome measures and analysis included completeness of tumor removal, perioperative mortality,facial nerve function,hearing,and tumor recurrence rate in different groups.Results:The mean tumor size in Group A was23mm and that in Group B was34mm and that in Group C was47mm. Total removal was achieved in97.3%of Group A patients and in96.8%of Group B patients and in97.4%of Group C patients. The anatomical integrity of the facial nerve and cochlear nerve was preserved respectively in100%,60.8%in Group A and in98.1%,29.1%in Group B and in99.6%,20.1%in Group C. The perioperative mortality rate in Group A was0%and that in Group A and Group C was respectively1.9%,0.7%. After surgery,350patients were followed up at least1year.100%patients in Group A,85.5%patients in Group B and78.2%patients in Group C had excellent or good facial nerve function. In28.6%of patients in Group A,29.2%of patients in Group B and37.5%of patients in Group C with good preoperative hearing lever(AAO-HNS Class A or B), it was preserved. The tumor recurrence rate in in Group A was1.7%and that in Group B was2.6%and that in Group C was1.1%.In terms of tumor size, a significant difference was found only in the rate of postoperative facial nerve function(P<0.05), not in the rate of completeness of tumor removal, perioperative mortality, postoperative hearing and tumor recurrence (P>0.05).Conclusions:1. Good result can be achieved in microsurgery treatment for different size of VSs via the retrosigmoid approach and intraoperative neurophysiological monitoring.2. The adhesion between tumor and facial nerve, rather than tumor size, mainly influence the rate of completeness of tumor removal.3. Long-term postoperative facial nerve function is significantly related with tumor size.4. Preoperative hearing level significantly correlates with postoperative hearing level, whatever tumor size or preoperative hearing lever is, hearing can be preserved or even improved in VS microsurgery.