Immediate reduction in temporal sensory summation after thoracic spinal manipulation

BACKGROUND CONTEXT: Spinal manipulative techniques (SMT) have shown clinical effectiveness in some patients with musculoskeletal pain. PURPOSE: We performed the current experiment to test whether regional pain modulation is to be expected from thoracic SMT. STUDY DESIGN/SETTING: Randomized experimental design performed in a university pain laboratory. OUTCOME MEASURES: The primary outcome was experimental pain sensitivity in cervical and lumbar innervated area. METHODS: Ninety healthy volunteers were randomly assigned to receive one of three interventions (SMT, exercise, or rest) to the upper thoracic spine. Participants completed questionnaires about pain-related affect and expectations regarding each of the interventions. We collected experimental pain sensitivity measures of cervical and lumbar innervated areas before and immediately after randomly assigned intervention. Mixed model analysis of covariance was used to test changes in measures of experimental pain sensitivity. RESULTS: No interactions or intervention (group) effects were noted for pressure or A-delta-mediated thermal pain responses. Participants receiving SMT had greater reductions in temporal sensory summation (TSS). CONCLUSIONS: This present study indicates thoracic SMT that reduces TSS in healthy subjects. These findings extend our previous work in healthy and clinical subjects by indicating change in the nocioceptive afferent system occurred caudal to the region of SMT application. However, the duration of reduction in TSS is unknown, and more work needs to be completed in clinical populations to confirm the relevance of these findings. (C) 2011 Elsevier Inc. All rights reserved.