Usefulness of electrophysiology in the prediction of outcome of Bell’s palsy patients

Abstract

Background: Bell’s palsy (BP) is a common idiopathic cranial mononeuropathy. The electrophysiological tests are one of supportive tools for localizing the site of facial nerve lesion, and to determine the severity and prognosis of the injury. The aim of this study was to evaluate the role of electrophysiology in the prediction of outcome of patients with Bell’s palsy. This study was carried out on 30 adult patients with Bell’s palsy. All study subjects were assessed clinically by Sunnybrook facial nerve grading score (SBS) and electrophysiologically by electroneurography (ENoG), blink reflex (BR), and electromyography (EMG); first evaluation was within 7th to10th day from onset, the second evaluation was done at 20th day, and the follow-up visit was after 1 month to assess the clinical grading system (SBS). Results: At 1 month, 20 patients (66.7%) had good recovery, while 10 patients (33.3%) had poor recovery according to the Sunnybrook scale. Multiple logistic regression analysis showed that the most significant predictive indicator of BP recovery was ENoG value and R1 latency of BR test. The receiver operating characteristic (ROC) curves showed ENoG degeneration index of 74.6%, considered as a critical cutoff value of non-recovery, with the sensitivity 95% and specificity 90%, and the highest specificity was with blink reflex parameters (R1, R2 latency) 100%. Conclusion: BR and ENoG were the best predictors of non-recovery of facial function, while EMG findings did not add any prognostic significance. The combination of both tests BR and ENoG, along with clinical findings can be considered a good indication in the acute phase of BP for the possibility to develop palsy residua.