The Application Of Preoperative Diffusion Tensor Imaging Combined With Intraoperative Neurophysiological Monitoring For Microneurosurgery Of Acoustic Neuroma

Objective: To study the value of preoperative diffusion tensor imaging and intraoperative neurophysiological monitoring for mirconeurosurgery of acoustic neuroma.Methods: The clinical data of 90 patients with acoustic neuroma by postoperative pathological diagnosis in Guizhou Provincal People’s Hospital between January 2012 to December 2015 were retrospectively reviewed. The patients were divided into two groups, in which test group was accepted microneurosurgery with diffusion tensor imaging(DTI) and intraoperative neurophysiological monitoring(IONM) January 2014 and December 2015, and control group was received routine microneurosurgery without those between January 2012 and December 2013. The position of facial nerves were observed carefully before operation by DTI and IONM, and the accuracy of this method was verified during surgical procedure.The degree of tumor resection,the facial nerve preservation rate and the rate of hearing preservation were compared between the two groups.Results: 1. The relationship between of facial nerve and acoustic neuroma was scanned with preoperative DTI: In 46 cases,the facial nerves of 38 cases(about 82.6%) was clearly showed by DTI,whose position were completely consistent with intraoperative findings and IONM. The facial nerves in 7 cases were in the anterior superior position to the tumors,18 cases in the anterior middle to the tumors,10 cases in the anterior inferior to the tumors, and 4 cases below the inferior end of tumors. due It is difficult to identify facial nerve due to its compression thinning and interference signals in 8 patients with large tumors.2.The degree of tumor resection: In test group, the rate of complete resection was attained 95.65%(44/46) and the rate of subtotal resection was 4.35%(2/46). In control group, the rate of complete resection was attained 81.81%(36/44) and the rate of subtotal resection was 18.19%(8/44). The data showed that the rate of complete resection in test group was higher than that in control group, and the differences in the degree of tumor resection between the two groups had statistical significance(P<0.05).3.Facial nerve function preservation: House-Brackmann classification method was used for evaluation facial nerve function preservation.One week after operation, the function preservation rate of facial nerve of the test group was 86.95%(40/46),and in the control group was 63.63%(28/44). Over 1 year’s follow-up after operation,the function preservation rate of facial nerve of the test group was 96.42%(27/28),and in the control group was 77.77%(28/36). The data showed that the function preservation rate of facial nerve of the test group was significantly higher than that of the control group,and the differences between the two groups had statistical significance at 1 week and at 1 year after operation(P<0.05),although no significance in the neurological function of facial nerve before operation(P>0.05).4. Hearing preservation: Electro-audiometer examination was adopted for evaluation hearing preservation.The hearing preservation of test group after one week was 23.91%(11/46),and 20.45%(9/44) in control group.Over 1 year’s follow-up after operation, the hearing preservation rate of the test group was 28.57%(8/28),and 22.22%(8/36) in control group.The data showed that the differences in hearing preservation between the group at 1 week and the other one at 1 year after operation had no statistical significance(P>0.05).Conclusion: The preoperative magnetic resonance DTI could find the course of facial nerve and the adjacent relationships with the tumor.DTI combined with IONM could improve the degree of tumor resection and facial nerve preservation.While no significant effect on retaining hearing.