Time to Complete Clinical Recovery and Its Predictors in Bell’s Palsy Patients Receiving Acupuncture: A Prospective Cohort Study

Background and Objectives: Bell’s palsy (BP) is the most common cause of acute unilateral peripheral facial nerve paralysis. The aim of this study was to evaluate the time to complete clinical recovery in patients with BP treated with acupuncture and to identify baseline clinical and electrophysiological predictors of recovery outcomes. In addition, electrophysiological characteristics at the time of complete clinical recovery were examined. Materials and Methods: This prospective, observational, uncontrolled cohort study included 1050 patients with clinically confirmed BP who received acupuncture as the only therapeutic intervention between January 2017 and August 2025. Clinical severity was assessed using the House–Brackmann (HB) and Sunnybrook (SB) grading systems. Electrophysiological evaluation included compound muscle action potential (CMAP) analysis and needle electromyography (EMG). Time-to-event analysis was performed using the Kaplan–Meier method and Cox proportional hazards regression analysis. Results: Complete clinical recovery was achieved in 843 patients (80.3%). The median time to recovery was 40 days (IQR 30–60). Patients with milder baseline deficits (HB II–IV) demonstrated significantly faster recovery than those with severe paralysis (HB V–VI) (log-rank p < 0.001). In multivariable Cox regression analysis, higher baseline HB grade, older age, and more severe EMG denervation were independently associated with slower recovery. Residual electrophysiological abnormalities persisted in most patients despite complete clinical recovery. Conclusions: Recovery from BP is a dynamic and heterogeneous process, significantly influenced by initial clinical severity and the degree of electrophysiological impairment. Combined clinical and electrophysiological assessment may contribute to more precise prognostic stratification and follow-up of patients with BP. Persistent electrophysiological abnormalities despite complete clinical recovery suggest that complete clinical recovery may precede complete neurophysiological regeneration of the facial nerve.