Electrophysiologic Monitoring Of The Facial Nerve During Resection Of Acoustic Neuromas

Objective : To explore methodologic, accuratissime and practicability of electrophysiologic monitoring of facial nerve during resection of acoustic neuromas, and relation to resection range of tumor with facial nerve anatomical preservation. arrive to promote the function preservation rate of facial nerve.Methods:A total of 28 patients with acoustic neuroma were enrolled in the study. According to Gormley's classification of intracranial tumor, in 28 patients the diameters of acoustic neuromas were 2～4cm (13 cases), <2cm(1 cases) and≥4cm (14 cases). Preoperative evaluation with House-Brackmann facial nerve function scale demonstrated there were GradeⅠ21 cases, GradeⅡ4 cases, and GradeⅢ3 cases. These patients were performed microsurgical resection of tumor via retrosigmoidal approach. We used Neurosign 100 (MAGSTIM Company, British) to monitor facial nerve during resection of 28 cases of acoustic neuromas and evaluated its facial nerve function with House-Brackmann Classification after 7 days.Result:Of 28 cases, 15 cases received total resection, 11 cases received subtotal resection and 2 case great partial, nobody death. In cases of total resection, the diameters of acoustic neuromas were 2～4cm(9 cases, 69.23%), <2cm(1 cases, 100%) and≥4cm (5 cases, 35.71%). The difficulty of total resection correlate to the diameter of tumor. The anatomic preservation of facial nerve was achieved in 27 cases (96.43%). Postoperative one week, the evaluation of facial nerve function demonstrated that there were GradeⅠ10 cases, GradeⅡ8 cases, GradeⅢ7 cases, GradeⅣ2 cases, GradeⅤ1 cases. In cases of well facial nerve function preservation, 9 cases received total resection, 7 cases received subtotal resection and 2 cases great partial. The facial nerve function preservation have related to the diameter of tumor and its degree of resection.Conclusion:It is demonstrated the intraoperative electrophysiologic monitoring of facial nerve is an effective technique in function preservation for the facial nerve. The technique is accurate and practicable. Skilled mircrosurgical technique is crucial for increasing rate of function preservation.