Predictive role of neurophysiological features on Bell’s palsy

EMG, blink reflex and nerve conduction studies in Bell’s palsy can help to determine the site of nerve injury and the lesion characterization: neurapraxia, axonotmesis and neurotmesis. Aim of this study was to determine electrophysiology role in predicting clinical outcome. We recruited 92 patients in a longitudinal prospective study. Three neurophysiological evaluations were performed 10–14 days, 17–21 days and 3 months after palsy onset. Clinical evaluation used the House-Brackmann scale, in a 6 months follow-up period. Reinnervation (p < 0.05; R = 0.49) and maximum contraction trace measured from orbicularis oculi (p < 0.05; R = 0.48) and oris (p < 0.05; R = 0.49) at baseline correlated with HB clinical scale. The presence of denervation at baseline significantly related with HB scale at second evaluation (orbicularis oculi: p < 0.05; R = 0.30; orbicularis oris: p < 0.05; R = 0.29). Combination of blink reflex and ENG demonstrated 2%-increased risk of not reaching the main outcome (HB scale ⩽2) for each additional point of degeneration index in patients who had absence of blink reflex. Regarding synkinesis, at first neurophysiological evaluation only the presence of orbicularis oculi denervation (HR = 3.31, p = 0.041) was associated with a poor prognosis. Baseline ENG/EMG and 17–21 days after palsy onset ENG and blink reflex are related to clinical outcomes in Bell’s palsy.