Evaluation of the effects of manual acupuncture and electroacupuncture at LI4 and LI11 on perception thresholds: a prospective crossover trial.

Objective: The objective of the study was to investigate and compare the effects of manual acupuncture (MA) and electroacupuncture (EA) on current perception thresholds (CPTs) using quantitative methods.

Methods: Twenty-nine healthy volunteers participated in this prospective crossover trial, in which three acupuncture methods were compared: control, MA, and EA. Acupuncture needles were inserted to a depth of 15 mm at LI4 and LI11 on the left side and retained for 30 min with or without electrical stimulation at a frequency of 2 Hz (EA and MA, respectively). The needles were removed and participants rested for 30 min. CPT in the left mental region was measured at 2000, 250, and 5 Hz, corresponding to the activation of Aβ, Aδ, and C-fibers, respectively, at four time points: baseline, T₀; 15 min after needle application, T₁; immediately after needle removal, T₂; and 30 min after needle removal, T₃. In the control session, only a sensory test was performed (without acupuncture).

Results: Significant effects of time course on CPT were observed (p < 0.001). CPT values increased significantly at T₁, T₂, and T₃, compared with those at T₀, at all stimulation frequencies during MA and EA. Changes in CPT values with EA were not significantly greater than those with MA.

Conclusions: Both MA and EA increased the sensory thresholds of Aβ, Aδ, and C-fibers in the mental region for ⩾30 min after needle removal. Additional of electrical stimulation may not confer additional benefits over needling alone.

Trial registration number: UMIN000017983 (University Hospital Medical Information Network Clinical Trials Registry).