A comparison of effects on regional pressure pain threshold produced by deep needling of LI4 and LI11, individually and in combination.

Objectives: To compare the effects of unilateral and bilateral needling of the same acupoint, and the effects of individual and combined needling of two distinct acupoints on pressure pain threshold (PPT).

Design: 22 subjects completed the randomised, dual blind (subject and evaluator) repeated measures study. PPT was measured before and after each intervention at ten sites (acupoints and nonacupoints) across the body with an algometer.

Interventions: The same manual acupuncture techniques were applied to four interventions of large intestine 4 (LI4) unilaterally; LI4 bilaterally; large intestine 11 (LI 11) unilaterally; and LI4 in conjunction with LI11, both unilaterally.

Main Outcome Measures: (1) Percentage change in PPT from preintervention baseline measured at the 10 regional sites following every intervention; (2) participants' perceptions of pain; needling sensations; tension during, and anxiety prior to, each intervention; and changes in practitioner behaviour.

Results: Following all four interventions, statistically significant increases in mean PPT were observed. These occurred at nine sites following the LI4 intervention either unilaterally or bilaterally; at six sites for LI11 intervention; and at five sites following the combined LI11 and LI4 intervention. These increases were significantly greater for the bilateral LI4 intervention than the unilateral LI4 intervention at only two sites (p < 0.02 and p < 0.0001). There were no statistically significant differences in the subjective perceptions among the four interventions.

Conclusion: The enhanced effects on PPT by the bilateral compared with the unilateral intervention at LI4 although limited, do provide some support for the traditional Chinese medicine (TCM) assumption that bilateral needling of the same point enhances the treatment effect. There was no support for the assumption that combined needling of points from the same channel should enhance the treatment effect and failure to obtain better effects by combined needling of points from the same channel could result from the interaction occurring during the combined needling.