Acupuncture for Inflammatory Pain and Central Sensitization - A Pilot Study

Acupuncture is used extensively by patients worldwide for a variety of illnesses. While research is beginning to show effectiveness in clinical pain, the mechanisms underlying how these effects are evoked are poorly understood. Experimental models in healthy human volunteers can more closely control the variables of acupuncture needling and begin to separate out the relative contribution of specific components of needling and needle stimulation. By examining acupuncture's effects on experimental inflammatory models with well-characterized physiologic mechanisms, hypotheses can begin to be generated regarding how acupuncture produces its clinical effects. We propose to establish a model which could be used as a template to examine the individual components contributing to acupuncture's clinical effects on inflammation and pain. We hypothesize that acupuncture will have analgesic and anti-inflammatory effects on a ultraviolet B induced cutaneous lesion as well as a model of heat pain testing which activates central sensitization.

Twenty healthy human volunteers will participate in a crossover study with active acupuncture and sham acupuncture interventions. They will be tested for their minimal erythemal dose (MED) to ultraviolet B exposure. An experimental lesion at 3x MED will be administered on the lower leg. Background information will be collected which could affect individuals' sensitivity to pain such as anxiety and depression, as well as their expectations regarding acupuncture treatment.

The following day they will return for the first experimental day. A measurement with Laser Doppler will quantify the inflammation in the ultraviolet B lesion. Heat pain testing will be performed using a computer controlled thermode both on and off the ultraviolet B lesion. On-lesion testing will be for heat pain threshold. Off-lesion testing will examine temporal summation of heat pain.

Next, a licensed acupuncturist will perform either true electroacupuncture or sham electroacupuncture in the region adjacent to the ultraviolet B lesion. Participants are blinded to the intervention, as is the examiner collecting data. Afterwards, Laser Doppler and heat pain testing will be repeated. The difference between pre-acupuncture and post-acupuncture measurements will represent the acupuncture -induced analgesic and anti-inflammatory effects.

Participants will return for another ultraviolet B exposure adjacent to the first, and will receive whichever sham or true acupuncture intervention was not performed on the first study day.