title: The mechanism of back pain relief by spinal manipulation relies on decreased temporal summation of pain.
abstract: The aim of the present study was to determine whether thoracic spinal manipulation (SM) decreases temporal summation of back pain. The study comprised two controlled experiments including 16 and 15 healthy participants, respectively. Each study included six sessions during which painful or non-painful electrical stimulations were delivered in three conditions: (1) control (2) light mechanical stimulus (MS) or (3) SM. Electrical stimulation was applied on the thoracic spine (T4), in the area where SM and MS were performed. In Experiment 1, electrical stimulation consisted in a single 1-ms pulse while a single or repeated train of ten 1-ms pulses was used in Experiment 2. SM involved articular cavitation while MS was a calibrated force of 25N applied manually for 2s. For the single pulse, changes in pain or tactile sensation in the SM or MS sessions compared with the CTL session were not significantly different (all p's>0.05). In contrast, temporal summation of pain was decreased in the SM session compared with the CTL session for both the single and repeated train (p's<0.05). Changes were not significant for the MS sessions (all p's>0.05) and no effect was observed for the tactile sensation (all p's>0.1). These results indicate that SM produces specific inhibitory effects on temporal summation of back pain, consistent with the involvement of a spinal anti-nociceptive mechanism in clinical pain relief by SM. This provides the first mechanistic evidence of back pain relief by spinal manipulation.
authors.affiliation: Département de Chiropratique, Université du Québec à Trois-Rivières, 3351 boul. des Forges, C.P. 500, Trois-Rivières, Québec G9A 5H7, Canada; Groupe de recherche en cognition, Neuroscience, Affect et Comportement (CogNAC), Université du Québec à Trois-Rivières, 3351 boul. des Forges, C.P. 500, Trois-Rivières, Québec G9A 5H7, Canada.
authors.forename: Christopher
authors.initials: C
authors.lastname: Randoll
authors.affiliation: Département de Chiropratique, Université du Québec à Trois-Rivières, 3351 boul. des Forges, C.P. 500, Trois-Rivières, Québec G9A 5H7, Canada; Groupe de recherche en cognition, Neuroscience, Affect et Comportement (CogNAC), Université du Québec à Trois-Rivières, 3351 boul. des Forges, C.P. 500, Trois-Rivières, Québec G9A 5H7, Canada.
authors.forename: Vincent
authors.initials: V
authors.lastname: Gagnon-Normandin
authors.affiliation: Département de Chiropratique, Université du Québec à Trois-Rivières, 3351 boul. des Forges, C.P. 500, Trois-Rivières, Québec G9A 5H7, Canada; Groupe de recherche en cognition, Neuroscience, Affect et Comportement (CogNAC), Université du Québec à Trois-Rivières, 3351 boul. des Forges, C.P. 500, Trois-Rivières, Québec G9A 5H7, Canada.
authors.forename: Jessica
authors.initials: J
authors.lastname: Tessier
authors.affiliation: Département de Chiropratique, Université du Québec à Trois-Rivières, 3351 boul. des Forges, C.P. 500, Trois-Rivières, Québec G9A 5H7, Canada; Groupe de recherche en cognition, Neuroscience, Affect et Comportement (CogNAC), Université du Québec à Trois-Rivières, 3351 boul. des Forges, C.P. 500, Trois-Rivières, Québec G9A 5H7, Canada.
authors.forename: Suzie
authors.initials: S
authors.lastname: Bois
authors.affiliation: Département de Chiropratique, Université du Québec à Trois-Rivières, 3351 boul. des Forges, C.P. 500, Trois-Rivières, Québec G9A 5H7, Canada; Groupe de recherche en cognition, Neuroscience, Affect et Comportement (CogNAC), Université du Québec à Trois-Rivières, 3351 boul. des Forges, C.P. 500, Trois-Rivières, Québec G9A 5H7, Canada.
authors.forename: Nabi
authors.initials: N
authors.lastname: Rustamov
authors.affiliation: Département de Chiropratique, Université du Québec à Trois-Rivières, 3351 boul. des Forges, C.P. 500, Trois-Rivières, Québec G9A 5H7, Canada; Groupe de Recherche sur les Affections Neuromusculosquelettiques (GRAN), Université du Québec à Trois-Rivières, 3351 boul. des Forges, C.P. 500, Trois-Rivières, Québec G9A 5H7, Canada.
authors.forename: Julie
authors.initials: J
authors.lastname: O'Shaughnessy
authors.affiliation: Département des Sciences de l'Activité Physique, Université du Québec à Trois-Rivières, 3351 boul. des Forges, C.P. 500, Trois-Rivières, Québec G9A 5H7, Canada; Groupe de Recherche sur les Affections Neuromusculosquelettiques (GRAN), Université du Québec à Trois-Rivières, 3351 boul. des Forges, C.P. 500, Trois-Rivières, Québec G9A 5H7, Canada.
authors.forename: Martin
authors.initials: M
authors.lastname: Descarreaux
authors.affiliation: Département de Chiropratique, Université du Québec à Trois-Rivières, 3351 boul. des Forges, C.P. 500, Trois-Rivières, Québec G9A 5H7, Canada; Groupe de recherche en cognition, Neuroscience, Affect et Comportement (CogNAC), Université du Québec à Trois-Rivières, 3351 boul. des Forges, C.P. 500, Trois-Rivières, Québec G9A 5H7, Canada. Electronic address: Mathieu.Piche@uqtr.ca.
authors.forename: Mathieu
authors.initials: M
authors.lastname: Piché
mesh_terms: D000328:Adult; D001416:Back Pain / Q000503:physiopathology*; D004558:Electric Stimulation / Q000379:methods; D005260:Female; D006801:Humans; D008159:Lumbar Vertebrae / Q000503:physiopathology; D008297:Male; D020393:Manipulation, Spinal / Q000379:methods; D008875:Middle Aged; D018482:Muscle, Skeletal / Q000503:physiopathology*; D059408:Pain Management / Q000379:methods; D010147:Pain Measurement / Q000379:methods; D055815:Young Adult
keywords: back pain; chiropractic; manual therapy; spine; vertebral