A Multifactorial Analysis of Facial Nerve Results in Surgery for Cerebellopontine Angle Tumors

Abstract

Preserving the function of the facial nerve remains a paramount objective in acoustic neuroma surgery. This study was undertaken to determine the influence of four independent variables on facial nerve outcome by means of a retrospective review of 111 surgical cases: 1) tumor size; 2) use of intraoperative facial nerve monitoring (IFNM); 3) completeness of tumor resection; and 4) surgical approach used. Partial tumor resection appeared to result in improved facial nerve outcome for patients with large tumors. Results indicated that tumor size did not correlate with facial nerve functional outcome, with no statistically significant differences observed among the three size categories. Facial nerve function was not found to depend on selection of either a translabyrinthine (n=47) or a suboccipital (n—55) surgical approach in that results were similar for both groups. Outcome data showed a trend in support of the use of IFNM, especially for large tumors, even though the differences between monitored and unmonitored groups were not statistically significant. This study describes the independent impact of the four factors generally thought to affect facial nerve outcome and, in addition, recommends the use of data stratification in reporting facial nerve function results.

Prognostic significance of preoperative electrophysiologic investigation for facial nerve outcome in acoustic neuroma surgery

“…5 We are aware of only one report denying the influence of tumor size as well as of surgical strategy. 10 None of the electrophysiologic changes presented above correlated with facial nerve outcome after surgery. This contrasts with the findings of Catalano and colleagues and those of Harner and coworkers, who reported differences in preoperative frequency of abnormal blink reflex, facial nerve conduction study, or facial electromyographic (EMG) findings (fibrillation potentials, amplitude reduction of the compound muscle action potential) between patients with a good facial nerve outcome and those with a poor outcome.…”

Prediction of postoperative facial nerve function in acoustic neuroma surgery

“…Similarly, immediate facial function was strongly predicted by tumour size. The correlation factor was r = 0.58, with an R 2 value of 0.33 and a P ‐value of < 0.0005. Long‐term facial function was strongly predicted by tumour size.…”

“…The procedure used was a linear regression model. Overall immediate facial nerve function was strongly predicted by stimulus intensity of the NIM‐2 monitor with a correlation factor of r = 0.45, an R 2 value of 0.2 and P ‐value of 0.007.…”

“…Long‐term facial function was strongly predicted by tumour size. The Correlation factor was r = 0.47, with an R 2 value of 0.2 and a P ‐value of 0.004.…”

“…Facial nerve monitoring has become an integral part of surgery of tumours of the cerebello‐pontine angle and it has resulted in better functional results in patients with large tumours. 1–2 The use of the nerve monitor during this form of surgery, in addition to its assistance in nerve identification and mapping and tumour dissection has been extended to include the prediction of postoperative facial nerve function 3,4 . Attempts to prognosticate accurately postoperative facial nerve outcome in cerebellopontine angle tumour surgery utilizing the facial nerve monitor have been reported in predominantly retrospective assessments.…”