Comparative Analysis Of Surgical Outcomes And Preservation Of Facial Nerve Function In Different Imaging Classification Of Vestibular Schwannomas

Objective: Compare the clinical characteristics and prognosis of different types of vestibular schwannomas,and explore treatment strategies to improve facial nerve function preservation.Methods: Cases were collected from January 2016 to December 2021 at the Second People’s Hospital of Shenzhen who underwent surgical resection and were pathologically confirmed with vestibular schwannomas.According to magnetic resonance imaging,they were divided into solid and cystic groups,and the cystic group was further classified into type A(central cysts with thick cyst walls)and type B(peripheral cysts with thin cyst walls)based on the overall position of the cyst and the thickness of the cyst wall.General information,preoperative symptoms,imaging indicators,preoperative hearing grading,tumor resection degree,facial nerve function level(preoperative,post-discharge,1 year postoperatively),complications,recurrence rate,and other indicators of patients were recorded.A retrospective analysis was performed on the above indicators to study the factors related to facial nerve function outcomes and differences in tumor recurrence or progression.Results: Among a total of 85 cases of tumors,19 cases(22.35%)were Cystic vestibular schwannoma(SVSs),and 66 cases(77.65%)were Cystic vestibular schwannoma(CVSs).Among them,31 cases(46.97%)were type A CVSs,and 35 cases(53.03%)were type B CVSs.Retrospective analysis showed that the Koos grade,surgical duration,facial nerve function at discharge,and facial nerve function at 1 year after surgery were statistically significant in the CVSs group compared to the SVSs group(P≤0.05):Cystic vestibular schwannomas have larger average tumor volume,longer surgical time,and worse short-term and long-term facial nerve function outcomes.Furthermore,for the cystic subgroup,comparative analysis showed that the surgical duration,cyst location,and facial nerve function at 1 year after surgery were statistically significant between type A and type B CVSs(P≤0.05):Type A cystic vestibular schwannomas have longer surgical time and worse long-term facial nerve function outcomes,Type B cysts are more prone to the brainstem side.Univariate analysis suggests that tumor size,tumor composition,extent of resection and surgical time are related to postoperative facial nerve function.Multivariate logistic regression analysis showed that showed that high resection degree,cystic tumor,and long surgery duration were risk factors for poor facial nerve function after surgery.Conclusion: Cystic vestibular schwannomas(CVSs)formation is a crucial factor affecting the surgical outcome of vestibular schwannoma resection.In our study,patients with CVSs who underwent resection surgery had worse facial nerve function than those with solid vestibular schwannomas(SVSs).There was no significant difference in short-term facial nerve function between type A and type B CVSs,but long-term facial nerve function was worse in type A CVSs.Additionally,tumor size,extent of tumor resection,and surgical time were important factors affecting facial nerve function.The faster growth rate of CVSs led to a tighter attachment between the tumor and neural vascular structures.Moreover,given the significantly higher proportion of large tumors in CVSs,larger tumors resulted in an increased resection time.When discussing poor facial nerve outcomes,we should consider the interaction of these factors.Therefore,more attention should be paid to protecting the facial nerve when dealing with CVSs.