On dermatomes, meridians and points: results of a quasiexperimental study

Traditional Chinese medicine (TCM) meridians and points run vertically, reflecting their function in the Zhang-Fu system (meridian pattern). However, the trunk's spinal nerves show a traverse orientation, or a 'horizontal pattern'.

The aim of the present work was to evaluate, via a cognitive quasiexperiment, whether the clinical indications of the points on the trunk are associated with their meridian function or with their innervation and visceral-somatic connection.

The points in each dermatome of the trunk were considered crosswise, regardless of their meridians. The clinical indications for each point were differentiated into two mutually exclusive categories: (a) vertical distribution effect (VDE) or 'meridian pattern', when indications were quite different regarding the indications for the other points on the dermatome; and (b) transverse distribution effects (TDE) or 'horizontal pattern', represented by mainly local or segmental indications except for Shu-Mu points. After observing that the proportions between both categories often exceeded 60% in pilot samples, 60% was adopted as the reference value.

A total of 22 dermatomes accommodated 148 points with 809 indications, of which 189 indications (23.4%) exhibited VDE features, whereas 620 (76.6%) exhibited TDE features.

A TDE/VDE ratio of 3 : 1 implies that the clinical indications for the points of any dermatome on the torso are similar, regardless of their meridians, and suggests that most of the indications for trunk points involve a 'horizontal pattern' due to their neurobiological nature. These findings may help in understanding acupuncture's neurobiology and clarify some confusing results of clinical research, for example, excluding sham acupuncture as an inert intervention for future clinical trials.