Predictive Value of Postoperative Electrophysiologic Testing of the Facial Nerve After Cerebellopontine Angle Surgery

Abstract

Our objective was to assess the ability of postoperative electroneuronography (ENoG) and electromyography (EMG) to predict clinical facial function 1 year postoperatively in patients with facial paralysis and an intact facial nerve after cerebellopontine angle surgery. The study was a prospective, nonrandomized, uncontrolled clinical trial on an outpatient basis, at a tertiary care hospital. Primary eligibility criteria include: (1) cerebellopontine angle (CPA) surgery with anatomical preservation of facial nerve, (2) complete facial nerve paralysis; and (3) 1 year follow-up. ENoG and EMG were measured at 1 and 3 months postoperatively, House-Brackmann facial nerve grade at 1 year postoperatively. The Kendall coefficient of rank correlation demonstrated that the 1 and 3 month postoperative ENoG data were significant predictors of ultimate facial nerve outcome. Tracking multiple ENoG examinations in a single patient, over time was of little predictive value. EMG was a poor predictor of facial nerve outcome. In general, patients with delayed facial nerve paralysis had better ultimate facial function than patients with immediate paralysis. Postoperative ENoG, but not EMG was a statistically significant predictor of ultimate facial nerve outcome after CPA surgery. Patients with delayed facial paralysis had better outcomes than those with immediate facial paralysis.