Needle Sensation and Personality Factors Influence Therapeutic Effect of Acupuncture for Treating Bell's Palsy: A Secondary Analysis of a Multicenter Randomized Controlled Trial

This study represents an innovative secondary analysis of a multicenter randomized clinical trial that investigated how psychological factors and specific needling sensations influence the outcomes of acupuncture in the treatment of Bell's palsy. Bell's palsy is a neurological condition that causes sudden weakness or paralysis of the facial muscles, significantly affecting patients' quality of life. The study included 316 patients with unilateral idiopathic Bell's palsy, aged 18 to 65 years, who presented with symptoms within 168 hours of onset. Participants were randomized into two groups: the De Qi group (159 patients), which received acupuncture with strong stimulation to elicit the De Qi sensation, and the control group (157 patients), which received acupuncture with weak stimulation.

The methodology included comprehensive assessments using Cattell's 16 Personality Factors Questionnaire (16PF), visual analog scales to measure different needling sensations, and the pretreatment mediator questionnaire to evaluate beliefs and prior experiences with acupuncture. The primary outcome was facial nerve function measured by the House-Brackmann scale at 6 months, with success defined as complete recovery (Grade 1). The results demonstrated clear superiority of the De Qi group, with 89.8% of patients achieving complete recovery compared with 70.8% in the control group, resulting in an adjusted odds ratio of 4.16. Logistic regression analysis revealed specific predictive factors for each group.

In the De Qi group, low baseline House-Brackmann scores and low Social Boldness scores on the 16PF were associated with better outcomes. In the control group, in addition to low baseline scores, low Vigilance and high Tension scores on the 16PF were predictive of better recovery. Path analysis revealed that among the various needling sensations evaluated, only the sensation of 'fullness' had a significant direct effect on the 6-month outcome. This finding suggests that the intensity of this specific sensation may be a useful biomarker for predicting treatment efficacy.

Investigators used sophisticated statistical methods, including the LASSO algorithm for variable selection and 10-fold cross-validation, ensuring analytical robustness. The findings on personality are particularly intriguing, suggesting that more reserved and hesitant patients may respond better to acupuncture with De Qi, possibly due to greater adherence to the acupuncturist's instructions and greater attention to bodily sensations. The clinical implications are significant, suggesting that personalization of acupuncture treatment based on personality characteristics may optimize therapeutic outcomes. The study contributes to understanding the psychophysiological mechanisms of acupuncture, offering valuable insights into how subjective and objective factors interact in the healing process.