Dorsal displacement of the facial nerve in XXXX surgery: clinical features and surgical outcomes of 21 consecutive dorsal pattern cases.

@entity1 @entity11702 @entity5513 @entity5
UNASSIGNED: In @entity5513 surgery, the facial nerve (FN) course varies among @entity1 , but a dorsal pattern is rarely observed. We retrospectively reviewed and classified 556 @entity5513 operated on via a lateral suboccipital retrosigmoid (LSO) approach into two groups: dorsal (group D) and non-dorsal (group @entity11702 ). The clinical features and outcomes including functional preservation of the FN, the extent of @entity5 resection, and the retreatment rate were compared. Among 556 cases, 21 (3.8  %) @entity1 with dorsal patterns were identified. No significant differences in clinical features or preoperative status were noted between groups D and @entity11702 . No significant differences in functional FN preservation were found between groups D and @entity11702 in the immediate postoperative period (90.5 and 83.0  %, respectively) or 1-year postoperatively (95.2 and 97.0  %, respectively). Compared with group @entity11702 , the extent of @entity5 resection was significantly less (p   <   0.0001) and the retreatment rate was significantly higher in group D (hazard ratio, 33.6; 95  % confidence interval [CI], 11.7-96.1; p   <   0.0001). In one dorsal pattern case, surgical resection was abandoned based on the intraoperative findings. Dorsal displacement of the FN was accurately predicted with preoperative imaging evaluations in just two cases. Functional preservation of the FN during @entity5513 surgery is achievable if the FN runs along the dorsal side of the @entity5 . However, a dorsal pattern, especially when the FN is broadened, is clearly associated with less complete @entity5 removal and a higher rate of retreatment than typical pattern cases.
