It is not yet known whether the vasodilatation observed was evoked exclusively by dry needling of active trigger points.
After needling, increases in average and maximum skin temperature were seen as follows: for the thigh, changes were +2.6☌ (average) and +3.6☌ (maximum) for the calf, changes were +0.9☌ (average) and +1.4☌ (maximum). The vasodilatation spread from 0.2 to 171.9 cm(2) and then gradually decreased. Acupuncture needle stimulation of active trigger points under infrared thermovisual camera showed a sudden short-term vasodilatation (an autonomic phenomenon) in the area of referred pain. In the third year of symptoms, coexistent myofascial pain syndrome was diagnosed. We report the case of a 22-year-old Caucasian European man who presented with a 3-year history of chronic sciatic-type leg pain. Although vasoconstriction in the area of a latent trigger point has been demonstrated, the vasomotor reaction of active trigger points has not been examined. Trigger point diagnosis is based on Travel and Simons criteria, but referred pain and twitch response are significant confirmatory signs of the diagnostic criteria. Some authors suggest that active trigger points in the gluteus minimus muscle can refer pain in similar way to sciatica. Sciatica has classically been associated with irritation of the sciatic nerve by the vertebral disc and consequent inflammation.