Background: An acupuncture treatment can reduce pain sensitivity in patients with
chronic whiplash associated disorders (WAD). But it has been hypothesized that many of
the experimental results in acupuncture research could be interpreted as stress-induced
analgesia.
Objective: The present study aimed at examining whether acupuncture has an effect on
the autonomic nervous system response in patients with chronic WAD and if this response is
related to the pain inhibition after an acupuncture session.
Study Design: Randomized crossover trial with blinded assessor.
Setting: Two private practices.
Methods: Thirty-nine patients with chronic WAD received 2 treatment sessions of identical
duration, with acupuncture and relaxation therapy randomly crossed over in the 2 visits.
The primary outcome measurement was the registration of autonomic nervous system
parameters (heart rate, skin conductance, and heart rate variability parameters) during the
administration of experimental pain. Endogenous analgesia was the secondary outcome.
Results: Following one acupuncture treatment session, there was a significant change for
2 parameters: the heart rate was slightly reduced and the skin conductance was raised.
Comparing the effects of acupuncture and relaxation, no differences were found with
respect to the change in any of the autonomic parameters. Further, the reduction in pain
sensitivity in response to acupuncture treatment was unrelated to any of the changes in
autonomic measurements.
Limitations: The results were observed after only one session of acupuncture.
Conclusion: In patients with chronic WAD, in response to a single treatment session, no
acupuncture specific effects on the autonomic response to pain assessment were present
and the analgesia after one session of acupuncture is not caused by stress-induced analgesia
but is more likely the result of an acupuncture specific reaction.
Key Words: Acupuncture, chronic whiplash, autonomic nervous system, pain analgesia,
heart rate variability, acupuncture analgesia