Seeing the body: a new mechanism for acupuncture analgesia?

The use of visual illusions to study how the brain gives rise to a representation of the body has produced surprising results, particularly in relation to modulation of pain. It seems likely that this research has relevance to how we understand acupuncture analgesia. Acupuncture supplies several different kinds of signal to the brain: touch in the preliminary examination for tender areas; needle stimulation, mainly of Aδ fibres; and sometimes visual input from the patient's sight of the needle insertion. In the light of recent research, all these are likely to modulate pain. There are implications here for clinical practice and for research. Acupuncture may be more effective if patients can see the needles being inserted. The use of non-penetrating stimuli to the skin or minimal needle insertion at non-acupuncture points as control procedures becomes more than ever open to question and this, in turn, has relevance for claims that acupuncture is indistinguishable from placebo.