Characterization of Deqi Sensation and Acupuncture Effect

This review article addresses one of the most fundamental concepts in traditional Chinese acupuncture: deqi, literally translated as 'arrival of vital energy.' Deqi represents a complex set of unique sensations experienced by both the patient and the acupuncturist during treatment. For the patient, it traditionally manifests as four principal sensations: suan (soreness or tenderness), ma (numbness or tingling), zhang (fullness, distention, or pressure), and zhong (heaviness). For the acupuncturist, deqi is perceived through the needle as a sensation of tension, tightness, and fullness, often described as 'a fish nibbling on the bait.' The review examines the considerable efforts made in recent years to develop standardized questionnaires that can adequately qualify and quantify the sensations of deqi. Several instruments have been developed, including the Vincent questionnaire (1989), the Park scale (2002), the Southampton questionnaire (SNSQ, 2008), and the Massachusetts General Hospital scale (MASS, 2007).

Each presents specific advantages and limitations, particularly in distinguishing genuine deqi from sharp pain, which is considered detrimental to treatment. Neuroimaging studies have revealed fascinating aspects of the cerebral mechanisms of deqi. Using functional magnetic resonance imaging (fMRI) and positron emission tomography (PET), researchers have found that deqi activates distinct patterns in the brain, primarily deactivation of the limbic-paralimbic-neocortical system, whereas sharp pain provokes activation. The hypothalamus, insula, and subcortical structures emerge as important components in mediating the effects of acupuncture.

Notably, the magnitude of the cerebral response to deqi is small (less than 1%), suggesting that acupuncture operates within physiological limits, which may explain its few side effects. Investigation of the physiological mechanisms has revealed that different types of nerve fibers transmit the various sensations of deqi. Numbness is transmitted by the faster-conducting Aβ fibers, whereas dull aching, heaviness, and distention are transmitted by the slower-conducting Aδ and C fibers. Deqi has also been shown to affect blood flow with a certain degree of meridian specificity.

The crucial question of the relationship between deqi and clinical efficacy remains controversial. Although traditional Chinese medicine considers deqi essential for therapeutic success, controlled clinical studies have produced mixed results. Some studies have found positive correlations between the intensity of deqi and clinical outcomes, while others have found no significant differences between true acupuncture (with deqi) and sham acupuncture. This discrepancy may reflect methodological differences, patient populations, or even styles of acupuncture, since some traditions, such as Japanese acupuncture, intentionally avoid provoking intense sensations.

The review highlights several important limitations in the field. There is no consensus on a standard method or instrument for measuring deqi, despite considerable efforts. The subjective nature of deqi, influenced by cultural factors and individual expectations, presents significant methodological challenges. The lack of rigorously controlled clinical trials specifically designed to investigate the need for deqi for acupuncture efficacy represents a critical gap in knowledge.