Electromyography in the prognostication of recovery in patients with acute peripheral facial nerve palsy: a systematic review

Objectives: Needle electromyography (EMG) may be used to characterise the severity of the injury in acute peripheral facial nerve palsy (FNP) to predict recovery and guide management, but its prognostic value and clinical utility remain controversial. The aim of this systematic review was to evaluate the role of EMG to prognosticate the recovery of facial motor function in patients with acute peripheral FNP. Design: A comprehensive search strategy was applied in PubMed, Embase, and Web of Science based on Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines. The main outcome measure was the accuracy of EMG in predicting long-term facial function at least 6 months following symptom onset. Results: Eleven studies were included comprising 3837 participants, with 91.6% of these diagnosed with Bell's palsy (BP). In BP patients, the positive predictive value and negative predictive value for a good outcome based on EMG findings ranged from 82.1% to 100% and 66.7% to 80.5%, respectively, with two out of three studies finding that EMG remained a significant predictor of the outcome on multivariate analysis. Three studies addressed the role of EMG in non-idiopathic FNP with two of these studies supporting EMG to predict prognosis. Conclusions: EMG is a useful tool to gain insight into the likely outcome to guide management decisions and counsel patients on their expectations, particularly in BP. However, given inconsistencies in its application and lack of evidence around non-idiopathic FNP, it should not currently be relied on to predict recovery. Ultimately, its prognostic value and widespread adoption are dependent on the implementation of a clear and standardised protocol in future high-quality studies and routine clinical settings.