The Surgical Treatment Of Large Vestibular Schwannomas And The Protection Of Facial Nerve

Background:Vestibular Schwannomas are benign neoplasms of Schwann cell origin.Studies documenting that large tumors(diameter > 30mm) are inclined to surgical treatment.But the Facial Nerve is compressed intensively due to the adjunction to the Vestibular Nerve,sometimes can’t be recogonized.As a result,the protection of Facial Nerve is extremly important during the surgical treatment. Objective:To investigate whether it is benefitical to the anatomical integrity and function reservation rate of Facial Nerve in the surgical treatment of large Vestibular Sahwannomas using via intraoperative neurophysiolygical monitoring and some other methods. Methods:Retrospective analysis of 53 cases of Large Vestibular Schwannomas via Retrosigmoid Approach in the NO.1 Neurosurgery Department of China-Japan Union Hospital of Jilin University from 2008 to 2015, of which 24 cases were under intraoperative neurophysiolygical monitoring.All data of the localization of facial nerve, extent of tumor removal,the anatomical integrity rate, the waveform recorded by intraoperative neurophysiolygical monitoring,and the function of Facial Nerve respectively before operation, 2 weeks, 3 months and 6 months after operation with House-Brackmann Grading Scale were recorded. Results:1.Localization:In 53 cases of Vestibular Schwannomas,Facial Nerve localized in anterior middle position in 45 cases,anterior upper in 1 case,anterior lower in 5 cases,encased in 2 cases.2.Extent of tumor: There are 2 cases(8.3%) of subtotal recession in monitor group,1 case(3.4%)in control group.3.The anatomical integrity of Facial Nerve:All 4 cases of subtotal recession are in control group,localizing around internal auditory foramen.4.The function preservation of Facial Nerve:(1)2 weeks after operation,there are HB I in 5,HB II in 8,HB III in 4,HB IV in 5,HB V in 2 cases in control group, HB I in 16,HB II in 5,HB III in 4,HB IV in 3, HB V in 1 cases in monitor group,which are significant statistical differences(P=0.023).(2)3 months after operation,there are HB I in 7,HB II in 7,HB III in 5,HB IV in 4,HB V in 1 cases in control group, HB I in 18,HB II in 4,HB III in 4,HB IV in 2,HB V in 1 cases in monitor group,which are significant statistical differences(P=0.034).(3)6 months after operation,there are HB I in 11,HB II in 6,HB III in 3,HB IV in 3,HB V in 1 cases in control group, HB I in 21,HB II in 6 cases,HB III in 1,HB IV in 1cases in monitor group,which are significant statistical differences(P=0.027).Conclusion:Intraoperative neurophysiolygical monitoring contributes to the anatomical integrity and function preservation rate of Facial Nerve in the surgical treatment of large Vestibular Schwannomas.But there is no difference in extent of tumor between two groups.