Introduction: Facial nerve dysfunction is a risk of acoustic neuroma resection, with tumor size, preoperative radiation, surgical expertise, nerve continuity, and evoked responses as associated variables. Our goals were to substantiate facial nerve outcomes in our patient cohort and identify correlates of recovery.
Methods: We performed a retrospective chart review of consecutive cases by a single neurosurgeon (JJM) over seven years. We identified 192 patients (mean follow-up 34 months). Facial nerve function was assessed post-operatively and at final follow-up, with outcomes dichotomized as good (House-Brackmann (HB) I-II) or poor (HB III-VI).
Results: Our series contained a significant percentage of large tumors (42% > 2.5 cm; 12% > 4 cm). Gross total (100% resection) or near-total resection (95-99% resection) was achieved in most (88%) cases, with recurrence or progression in 7% of patients with at least 2 year follow-up. Surprisingly, although tumor size was inversely correlated with extent of resection (p<0.001), it was not associated with facial nerve outcomes. Interestingly the surgical approach (retrosigmoid 64%, translabyrinthine 32%, middle fossa 4%) was not associated with facial nerve outcome. Interestingly, surgeon’s impression of an abnormal appearing facial nerve intra-operatively was strongly associated with HB score immediately following surgery (p=0.0006), while the amplitude required for proximal stimulation at end of resection correlated with the final HB grade (p<0.0001). 39% of patients had poor function postoperatively, but most improved with 88% of patients having good facial nerve function at last follow-up.
Conclusions: Immediate facial nerve weakness after aggressive surgical resection of acoustic neuromas is common, yet the majority of patients (90%) improve to HB I-II. Facial nerve outcomes correlate with surgical appearance of facial nerve and intraoperative stimulation, but not tumor size or surgical approach. These results justify the intention for gross total resection in experienced hands, modified by intraoperative judgment based on monitoring and facial nerve appearance.
Patient Care: Based on this study, we will be able to provide patients with more accurate information about their prognosis for recovery of facial nerve function in the perioperative period.
Learning Objectives: Following this presentation the viewer should be able to describe the patient characteristics and intraoperative findings associated with facial nerve dysfunction following acoustic neuroma resection.