Association of neutrophil-to-lymphocyte ratio and initial facial weakness with electroneurography results in early-stage Bell’s palsy: A retrospective cohort study

This study aimed to investigate the clinical factors, including neutrophil-to-lymphocyte ratio (NLR) and the initial House-Brackmann (H-B) grade, associated with electroneurography (ENoG) in patients with early-stage Bell's palsy. This retrospective cohort study evaluated 97 adults (≥18 years) with early-stage Bell's palsy diagnosed at our university hospital between January 2014 and September 2021. The medical records of these patients, including the NLR and the initial H-B grade, were reviewed. The degree of axonal loss was calculated using the compound muscle action potential (CMAP) amplitude ratio measured by ENoG. Patients were classified into 2 groups based on the degree of axonal loss: poor and good results, defined as >90% loss of amplitude (ENoG results < 10%) and ≤90% loss of amplitude (ENoG results ≥ 10%), respectively. Multivariable analysis revealed that an initial H-B grade II-III (odds ratio [OR], 4.79; 95% confidence interval [CI], 1.39-16.46) and an NLR < 1.92 (OR, 5.54; 95% CI, 1.85-16.53) were associated with good ENoG results. In our construction of a classification and regression tree (CART) model that considered various variables to predict the degree of axonal loss, the first partitioning node was initial H-B grade II, and CART analysis with minimal classification error found that an NLR of 1.61 was the second partitioning predictor. The model showed a sensitivity, specificity, and an accuracy of 87.5%, 80%, and 85.6%, respectively. By measuring the NLR at the time of Bell's palsy onset and initial facial weakness evaluated by H-B grade, it may be possible to predict subsequent axonal loss calculated by ENoG, which is performed 10 to 14 days after symptom onset.