Heat stimulation on the skin for medical treatment: can it be controlled?

It has become increasingly important for evidence-based medicine to have a proper control for randomized-controlled trials. However, appropriately controlling manual therapies such as moxibustion has proved challenging. Our team designed a novel device based on sensory illusion, and tested its feasibility.

A sham moxibustion device was constructed to allow participants to feel moxibustion treatment without actually stimulating the corresponding acupoint. The device consisted of two pieces of aluminum, each shaped like a horseshoe, so that the center of the device would not touch the skin. Participants perceived two heat stimuli as one when the distances of two heat sources were within 15 mm on the forearm. The thermal stimulation of the sham device was adjusted to the lowest possible temperature, but enough to elicit a heat sensation (39°C), while that of verum was set at around 44°C. The subject blinding, tested in 30 healthy volunteers, was successful. With the exception of 1 subject, subjects in the sham group described the sensation as a warm solid circle, unable to differentiate between two-pieced sham moxibustion and verum moxibustion.

This preliminary study indicates that this device may serve as an appropriate control for clinical studies of moxibustion, but more research is clearly needed. A validated sham moxibustion device based on sensory illusion may contribute in expanding knowledge of somatosensory studies.