4. Discussion
neck/shoulder stiffness, pain
This is the first randomized placebo-controlled study to evaluate the efficacy of superficial needle insertion on essential neck/shoulder stiffness compared with skin-touch and no-touch placebo needles under double-blind conditions. No-touch treatment significantly improved the neck/shoulder stiffness as penetrating and skin-touch treatments. However, the efficacy of the no-touch treatment was not comparable to penetrating treatment one day later. The results indicated that the acupuncture ritual had a significant impact on the subjective improvement in neck/shoulder stiffness, and skin piercing had some effect on the acupuncture ritual.In this study, we employed two kinds of placebo needles. To reveal the specific effect of skin piercing that is a characteristic component of acupuncture, a skin-touch placebo needle is indispensable. The blinding effect of skin-touch needles, which makes patients feel that they are receiving acupuncture, has been well validated [However, it should be noted that skin pressing with a nonpenetrating acupuncture needle is physiologically active; thus, a skin-touch placebo is argued to be an inappropriate control to reveal the efficacy of acupuncture [As for the efficacy with no-touch treatment, at which there were only a few patients’ correct guesses with certainty, as well as the other two treatments, the same level of significant improvement was comparable to the other two treatments immediately after. The efficacy of the no-touch treatment could be attributed to the equivalent amount of placebo effect of the acupuncture ritual in the penetrating and skin-touch treatments. The comparable improvement with no-touch treatment to the other two treatments despite a larger number of correct patients’ guesses on no-touch treatments than the other treatments indicates that usage of placebo device per se was critical to reduce bias, but not for whether the patient’s guess was correct or not. This speculation is supported by the meaningful efficacy of reducing subjective complaints observed in an open level placebo study in which the participants were clearly explained that they would take an inactive (i.e., ‘‘inert’’) placebo such as a sugar pill prior to treatment [However, it was also demonstrated that superficial skin piercing of 5 mm depth did not have a specific effect over skin press with a skin-touch needle. The reason for this might be that input to the central nervous system with a skin-touch needle was very similar to 5 mm needle insertion; in fact, acupuncture sensation including skin penetration pain with a 5 mm needle insertion and skin-touch needle are comparable [From the current results, the patients in the three groups had the same level of expectation, which plays a key role in placebo effects, arising from the ritual of acupuncture; moreover, placebo effect might be largely involved in the efficacy of each treatment [Given that neck/shoulder stiffness is increasingly prevalent in a highly stressful society, perhaps because of computer use [The limitations of this study include only a single treatment session, short follow-up, and shallow insertion; the patients knew that the two types of placebo needles were options. Further research is warranted with multiple treatments using more needles and/or deeper insertion while telling the patient that there is one placebo arm and not two.