To investigate the risk factors for facial nerve function impairment following microsurgical resection of acoustic neuroma (AN) via suboccipital retrosigmoid approach.

The clinical data of 140 AN patients receiving microsurgical resection via suboccipital retrosigmoid approach in Neurosurgery Department of Mianyang City Central Hospital from January 2017 to January 2020 were retrospectively analyzed. All patients were followed up for 6 months. The degree of facial nerve damage of patients was assessed using H-B facial nerve grading system (HBFGS). The age, gender, tumor diameter, tumor resection range, operative time, intraoperative facial nerve monitoring, facial nerve location and the adhesion between the facial nerve and tumor capsule and other factors were taken as analysis factors. Logistic regression was used to analyze the independent risk factors affecting postoperative facial nerve function impairment.

The patients were divided into two groups according to the HBFGS scale of facial nerve 6 months after operation. HBFGS grade Ⅰ-Ⅲ was mild-to-moderate disorder group (78 cases), and HBFGS grade Ⅳ-Ⅵ was severe disorder group (62 cases). Univariate analysis showed that mild-to-moderate disorder group had lower maximum tumor diameter and shorter operation time than those of severe disorder group (P<0.05), moreover, tumor resection rang, intraoperative facial nerve monitoring, and the adhesion between the facial nerve and tumor capsule also showed significant difference between two groups (P<0.05). Logistic multivariate regression analysis showed that the maximum tumor diameter>3.13 cm, partial resection and subtotal resection of the tumor and moderate and severe adhesion between the facial nerve and tumor capsule were independent risk factors affecting postoperative facial nerve impairment (OR>1, P<0.05), and intraoperative facial nerve monitoring was a protective factor for severe postoperative facial nerve impairment (OR<1, P<0.05).

The tumor diameter, tumor resection range, intraoperative facial nerve monitoring and the severity of the adhesion between the facial nerve and tumor capsule are independent factors affecting facial nerve function impairment following microsurgical resection of AN via suboccipital retrosigmoid approach.