[Function of the facial nerve after operative treatment of acoustic neurinomas. Influence of intraoperative monitoring].

The aim of this study was to evaluate the influence of intraoperative monitoring on the function of the facial nerve after surgical treatment of acoustic neurinomas, classified according to the grading system of Stennert. One hundred thirty patients were divided into two groups. The first group underwent surgery without intraoperative facial monitoring; the second group included intraoperative facial monitoring. Concerning degree of paresis, preoperatively there was no statistically significant difference between the two groups (group 1: 0.77+/-1.5; group 2: 0.4+/-1.2). Despite structural preservation of the facial nerve, postoperative deterioration of its function was observed which consecutively improved postoperatively. Postoperatively, the mean degree of paresis increased to 4.4+/-3.0 in group 1 and 2.4+/-2.3 in group 2. For better understanding of the role of intraoperative monitoring, we investigated the outcome of patients with acoustic neurinomas who underwent surgery over the following 6 months postoperatively. At that time, function improved by 4.1+/-3.2 (group 1) and 2.0+/-2.3 (group 2). We could show that intraoperative monitoring of the facial nerve was a significant factor for better postoperative function in patients undergoing microsurgical excision of neurinomas (P=0.001) .