Does Acupuncture Activate Endogenous Pain Inhibition in Chronic Whiplash?

Does Acupuncture Activate Endogenous Pain Inhibition in Chronic Whiplash Associated Disorders? A Randomized Cross-over Trial

This physiological study examines whether acupuncture exerts short-term effects of analgesic mechanisms in patients with chronic whiplash pain. More specifically, it is examined whether acupuncture activates brain-orchestrated pain inhibitory action.

Many patients with chronic pain, including those with chronic whiplash-associated disorders (WAD), show features of central sensitization (CS), a process characterized by generalized hypersensitivity of the somatosensory system. it would be worthwhile identifying treatments able of activating the dysfunctional endogenous pain inhibition in patients with CS and chronic WAD.

Acupuncture is a treatment method widely used for patients with chronic pain, including those with chronic WAD. The effectiveness of acupuncture for the treatment of chronic (neck) pain is supported by several randomized controlled clinical trials, systematic reviews including meta-analyses. However, the effect-sizes are rather small and only short-term effects have been shown consistently.

A randomized cross-over trial comparing acupuncture with relaxation is conducted in order to examine whether acupuncture vs. relaxation for patients with chronic WAD results in:

1. Immediate activation of endogenous pain inhibition (i.e. conditioned pain modulation);
2. Concomitant pain relief;
3. And reduced disability level. Further it is examined whether acupuncture vs. relaxation results in different autonomic nervous system responses.

Inclusion Criteria:

• a diagnosis of chronic WAD grade 1 to 3 according to the criteria as defined by the Quebec Task Force classification
• chronic neck pain and WAD persisting for at least 3 months
• age between 18 and 65 years

Exclusion Criteria:

• classified as WAD grade 4 (neck complaints including fracture or dislocation, or injury to the spinal cord)
• pregnant
• initiated a new conventional therapy during the study period
• taking analgesic drugs 48 hours before testing and/or nicotine, alcohol and caffeine 24 hours before testing