Therapeutic effect of electroacupuncture at different intensities on peripheral facial paralysis and its influence on brainstem excitability

OBJECTIVES: To observe the clinical effect of electroacupuncture (EA) at different intensities on peripheral facial paralysis (PFP) and its influence on brainstem excitability. METHODS: Sixty-six patients with PFP were randomly assigned to a motion-threshold EA group (22 cases, 2 dropped out), a sensory-threshold EA group (22 cases, 1 dropped out) and a sham-EA group (22 cases, 2 dropped out). Sibai(ST2), Dicang(ST4), Hegu(LI4) and Yuji(LU10) on the affected side were selected in 3 groups and stimulated with EA. In the motion-threshold EA group, the stimulation intensity was determined by the visible muscle jumping in the local area. In the sensory-threshold EA group, the minimal sensory stimulation was adjusted. In the sham-EA group, the skin was not invaded and no electric stimulation was delivered. In each group, the intervention was given once every 3 days, 30 min each time and the duration of treatment was composed of 20 interventions. At the baseline (T0), after the 10th intervention (T1), after the 20th intervention (T2) and in 1 month followup after treatment completion (T3), the House-Brackmann scale for grading facial nerve function (H-B score) and the facial disability index (FDI, comprising physical function [FDIP] and social function [FDIS]) were assessed separately. Besides, the changes of facial nerve injury rate and blink reflex (BR) were observed before and after treatment. RESULTS: In the self-group comparison, H-B score at T2 and T3 was improved significantly compared with that at T0 (P<0.001, P<0.05) in the motion-threshold EA and sensory-threshold EA groups separately;FDIP score was increased significantly at T2 and T3 in the motion-threshold EA group (P<0.001), and FDIP score was increased significantly at T2 in the sensory-threshold EA group (P<0.01);the FDIS score was reduced significantly from T1 to T3 in the motion-threshold EA group (P<0.05, P<0.001), and it was reduced significantly at T2 and T3 in the sensory-threshold EA group (P<0.001, P<0.05). In comparison with the sham-EA group at the same time point, H-B score and FDIS score at T2 and T3 were decreased in the motion-threshold EA group and the sensory-threshold EA group (P<0.01, P<0.05, P<0.001). After treatment completion, in the motion-threshold EA group and the sensory-threshold EA group, the injury rate of the temporal and buccal branches of the facial nerve was declined (P<0.01, P<0.001) compared with baseline, and it was lower than that of the sham-EA group (P<0.001, P<0.01). Besides, the R2 latency was shorter in comparison with the baseline in the motion-threshold EA group and the sensory-threshold EA group (P<0.01), and the latency in the motion-threshold EA group was superior to the sensory-threshold EA group (P<0.05). CONCLUSIONS: EA at both motion threshold and sensory threshold obtains a similar therapeutic effect on PFP, and it effectively relieves symptoms of PFP and presents a certain long-term effect. Motor-threshold EA demonstrates modulatory effect on the brainstem's neural reflex pathway.