An investigation of symptom-specific muscle hyperreactivity in upper extremity cumulative trauma disorder.

OBJECTIVE: The study examined symptom-specific muscle hyperreactivity in patients with chronic pain with upper limb cumulative trauma disorder (CTD). DESIGN: Four tasks were presented in counterbalanced order and included neutral, general stressor, personal stressor, and pain stressor tasks. Ratings of stressfulness and recordings of skin conductance level confirmed the effectiveness of the experimental manipulations in inducing stress experiences for all subject groups. SETTING: The study was conducted in a university research center. PATIENTS: Thirty patients with CTD were matched as closely as possible for age and gender to control groups of chronic low back pain, arthritis, and pain-free subjects. OUTCOME MEASURES: Surface electromyograph recordings were taken from the frontalis, forearm flexors, trapezius, and lower back during baseline and tasks. RESULTS: The study found no evidence of greater muscle tension increases or extended duration of return to baseline for the CTD or low back pain patients at any of the muscle sites for any of the tasks in comparison to control groups. CONCLUSIONS: The results indicate that symptom-specific psychophysiological responses may be limited to certain subgroups rather than being characteristic of chronic musculoskeletal pain patients in general.