Facial nerve protection and its function evaluation during operation for large and medium acoustic neuroma

Objective To explore the protection of the facial nerve and evaluation of its function during operation for large and medium acoustic neuroma . Methods The suboccipital retrosigmoid transmeatal approach was used in all cases. Intraoperative monitoring was used to protect facial nerve and evaluate its function. Results Total removal was achieved in 156 patients(93%) and subtotal in 12(7%). The facial nerve was preserved anatomically in 154 cases(92%) ,H-B Grade Ⅰ~Ⅱ in 89(53%),Grade Ⅲ~Ⅳ in 57(34%),Grade Ⅴ~Ⅵ in 22(13%).Stimulative intensity at the end of operation is related to the function of facial nerve, The lower, the better. The function of facial nerve may be Ⅰ~Ⅱgrade when stimulative intensity is 1~3V. The function of facial nerve could not recover when stimilative intensity is above 15V. Conclusions Skilled microsurgical technique is crucial for increasing anatomical and function preservation. Intraoperative monitoring might increase the anatomical and function preservation rate of facial nerve and also can evaluate its function.