To compare the muscular reactivity of patients with chronic back pain
(CBP) to different psychological stressors with the reactions of healthy controls. We also investigated the specificity of muscular reaction near the site of pain in comparison to distal sites. The symptom-specificity model
of chronic pain postulates that increased muscle tension in CBP patients may be responsible for the development and maintenance of chronic pain.
We studied a total of 54 CBP patients with musculoskeletal pain of the lower back, midback, or neck and 62 healthy controls, matched with CPB patients. Muscle tension and skin conductance level (SCL) were assessed. The four experimental conditions included back focusing, a personally relevant stressor, a cognitive stressor, and a social stressor.
CBP patients showed patterns of higher muscular reactivity in the lower back region for chronic low back pain (CLBP) patients during the exposure to a personally relevant stressor, a cognitive stressor, and a social stressor. Additionally, CLBP patients showed specific muscular responses in the lower back.
The results support the assumptions made by the symptom-specificity model
of CBP, but only for lower back, not for midback and neck. Treatment programs of CLBP should include specific combined relaxation and stress management components.
CBP = chronic back pain; CLBP = chronic low back pain; EMG = electromyography; BMI = body mass index; SCL = skin conductance level; ns = nonsignificant.