Acupuncture De-qi: From Characterization to Underlying Mechanism

De-qi represents one of the most fundamental concepts of traditional Chinese acupuncture, originally described in the Nei Jing (Inner Classic) as an essential indicator of therapeutic success. This review article presents a comprehensive analysis of current scientific knowledge about this complex phenomenon, exploring everything from its subjective characteristics to the underlying neurobiological mechanisms. Modern research has focused on understanding three main aspects of De-qi: characterization of subjective sensations, factors that influence its manifestation, and the objective physiological responses it triggers. Regarding subjective sensations, multiple studies using validated scales show that De-qi manifests primarily through sensations described as distension (94% of cases), dull aching (81%), electric shock (81%), and numbness (78%).

These sensations are consistent with traditional Chinese medicine descriptions, characterized as a unique experience between pleasure and acute pain — a tolerable, dull pain that patients often describe as reassuring. Important studies such as those by White et al. developed specific questionnaires to differentiate De-qi from acute pain, identifying two main clusters: 'aching De-qi' (including deep pain, heaviness, and pressure) and 'tingling De-qi' (including tingling, warmth, and numbness). Neurobiological research reveals that different De-qi sensations activate distinct types of nerve fibers: numbness correlates with Aβ/γ fibers, distension and heaviness with A-delta fibers, and pain with C fibers.

Factors influencing De-qi primarily include acupoint specificity, needle manipulation techniques, stimulation methods, and, to a lesser extent, psychological factors. Acupoint specificity emerges as a fundamental intrinsic factor — neuroimaging studies show that even when similar sensations are elicited at true versus sham points, brain responses differ significantly. Needle manipulation, especially rotation, was shown to substantially increase the intensity of De-qi, with ultrasonographic studies revealing that rotation causes thickening of the connective tissue around the needle, generating mechanical signals through deformation of collagen fibers. Objective physiological responses to De-qi span multiple systems.

In the autonomic nervous system, De-qi induces reduced sympathetic activity and increased parasympathetic activity, manifested through decreased heart rate and decreased ratio between low- and high-frequency components of heart rate variability. Electroencephalographic studies show that participants with more intense De-qi sensations exhibit significant changes in alpha waves, indicating a correlation between brain changes and sensation intensity. Functional magnetic resonance imaging research reveals particularly intriguing findings: predominant De-qi (without acute pain) causes deactivation of BOLD signals in the limbic-paralimbic system and subcortical structures, while acute pain sensations activate these same regions. This deactivation may represent the mechanism by which acupuncture exerts its therapeutic effects, since the limbic-paralimbic system regulates emotions, cognition, consciousness, and autonomic, endocrine, and immune functions.

The article highlights important limitations in current research, including the fact that most studies were conducted in healthy individuals rather than in patients with pathological conditions. Preliminary research suggests that patients in disease states respond differently — for example, heroin-dependent individuals show significantly higher De-qi scores and more robust hypothalamic activation compared with healthy individuals. The clinical implications are substantial. The evidence suggests that De-qi is not merely an epiphenomenon, but an active indicator of neurobiological processes that contribute to therapeutic efficacy.

The ability to elicit adequate De-qi may be crucial to optimizing clinical outcomes, requiring careful attention to point selection, insertion techniques, and needle manipulation. For modern clinical practice, this knowledge provides a scientific basis for traditional techniques and suggests that monitoring De-qi quality may serve as a biomarker for predicting therapeutic efficacy.