Application of intraoperative neurophysiological monitoring for the large acoustic neuroma

Abstract

Objective To explore the function of intraoperative monitoring by brainstem auditory evoked potential and free electromyography during the operation of large acoustic neuroma for improving the operation more accurately and safely. Methods The intraoperative monitoring of affected cranial nerve and brainstem function respectively by brainstem auditory evoked potential and free electromyography was performed in 26 patients with large acoustic neuroma. According to the monitoring result the strategy and method of surgery was adjusted. Facial nerve function was assessed using the House-Brackmann facial nerve grading system immediately after two weeks of surgery.Results 23 cases (88 ％) achieved total resection,3 cases (12 ％) achieved subtotal resection. The facial nerve was preserved anatomically in 25 patients.According to the House-Brackmann facial nerve grading system,21 cases (80 ％) got preserve of facial nerve function in grade Ⅰ - Ⅱ, 3 cases (12 ％) got preserve of facial nerve function in grade ]Ⅲ-Ⅳ and 1 cases (4 ％) got preserve of facial nerve function in grade Ⅴ after two weeks of surgery.Conclusion Intraoperative physiological monitoring may increase the anatomical and functional preservation rate of affected cranial nerve and also may improve the operation more accurately and safely. Key words: Neuroma,acoustic; Evoked potentials,auditory,brain stem; Microsurgery; Facial nerve electromyography