The needling sensation: A factor contributing to the specific effects of acupuncture?

Abstract

Acupuncture is a complex intervention, and there are both specific and non-specific influences associated with its therapeutic benefit. Although large randomized controlled trials (RCT) and systematic reviews have demonstrated the efficacy of acupuncture, the conclusions are controversial due to the lack of a significant difference in the results between real and sham acupuncture. This similarity may be due to the omission of important components of the acupuncture treatment itself, such as the needling sensation. The needling sensation is considered to represent an important component of acupuncture. Despite this importance, several RCTs have lacked data on whether the needling sensation has been achieved. From a Traditional Chinese Medicine (TCM) perspective, the needling sensation, deQi, is a combination of unique sensations that are interpreted as the flow of Qi, or “vital energy.” Furthermore, acupuncture is believed to be successful only upon the arrival of “vital energy,” Qi. This state is suggested to be essential to the specific therapeutic effect of acupuncture. From a biomedical perspective, acupuncture excites sensory receptors and nerve fibers in the stimulated tissue, resulting in a needling sensation. Moreover, acupuncture induces both the deactivation of a limbic–paralimbic–neocortical network in the brain (the default mode network and the anti-correlated task-positive network) and the activation of somatosensory regions. A distinct needling sensation is associated with a marked deactivation of these brain networks, whereas the lack of a needling sensation (as during sham needling) is associated with significantly less deactivation. Conversely, when acupuncture induces sharp pain sensations, there is an activation of these networks instead. In a clinical context, this difference means that the therapist needs to identify a stimulation intensity that is scaled to the needling response of each patient, i.e., a sharp uncomfortable pain sensation during the needle stimulation should be avoided.

Both the empirical bases of TCM and biomedical acupuncture research suggest that the therapist should strive for a needling sensation during an acupuncture treatment. If such a sensation is not achieved, are the specific effects of acupuncture likely smaller? This conclusion suggests that deQi is part of a proper acupuncture treatment and that the experience of a needling sensation should universally be assessed and reported in all types of clinical and experimental trials.