Facial nerve function following cerebellopontine angle surgery: prognostic value of electroneurography

Preoperative counseling of patients, regarding facial nerve function following cerebellopontine angle (CPA) surgery, has remained a difficult task. Facial nerve electroneurography (ENoG) or evoked electromyography can detect subclinical neural degeneration. This test was used in 44 patients undergoing CPA surgery, and facial nerve function was followed postoperatively. A normal preoperative ENoG study appeared to predict an 81 percent and 84 percent chance of good (House grade I-II) early and late postoperative facial function, respectively. An abnormal test is not as reliable. The relation of preoperative ENoG results with tumor size and tumor adherence to the facial nerve is investigated. Electroneurography appears to be a useful preoperative test when counseling patients regarding facial function following CPA surgery.