Previous research suggested that patients with Fibromyalgia (FM) experience a higher pain intensity (clinical pain) than do patients with musculoskeletal pain after negative emotional priming compared to positive priming.
To further examine affective [defined as "influenced by or resulting from emotions"] pain modulation in FM, we applied an experimental pain induction to compare 30 patients with FM with 30 healthy (pain-free) participants (HC), and 30 patients with back pain (BP).
For another group of 30 patients with somatoform pain disorder (SF), we predicted the same pain modulation as for FM. [Note: somatoform pain disorder is defined as "persistent and chronic pain at one or more sites in which psychological factors are thought to play a role."] As primes we presented positive, neutral, negative, and pain-related pictures and assessed pain intensity in response to a fixed pressure weight.
Overall, picture valence modulated pain intensities (in the order of pain-related > negative pictures > neutral), but the pain intensities between neutral and positive pictures did not differ significantly.
SF [somatoform pain disorder patients] reported significantly higher pain intensities than did BP [back pain] and HC [healthy controls]; FM were in between, but did not differ significantly from the three other groups. There was no interaction of priming and group.
Affective modulation of pain was not specifically altered in FM and SF, but SF were more sensitive to pressure pain than BP and HC.
Source: European Journal of Pain. 2007 Aug 25; [E-publication ahead of print] PMID: 17723312, Arnold BS, Alpers GW, Sub H, Friedel E, Kosmutzky G, Geier A, Pauli P. Klinikum Bad Bocklet, Bad Bocklet, Germany.