title: The effect of experimental low back pain on lumbar muscle activity in people with a history of clinical low back pain: a muscle functional MRI study.
abstract: In people with a history of low back pain (LBP), structural and functional alterations have been observed at several peripheral and central levels of the sensorimotor pathway. These existing alterations might interact with the way the sensorimotor system responds to pain. We examined this assumption by evaluating the lumbar motor responses to experimental nociceptive input of 15 participants during remission of unilateral recurrent LBP. Quantitative T2 images (muscle functional MRI) were taken bilaterally of multifidus, erector spinae, and psoas at several segmental levels (L3 upper and L4 upper and lower endplate) and during several conditions: 1) at rest, 2) upon trunk-extension exercise without pain, and 3) upon trunk-extension exercise with experimental induced pain at the clinical pain-side (1.5-ml intramuscular hypertonic saline injections in erector spinae). Following experimental pain induction, muscle activity levels similarly reduced for all three muscles, on both painful and nonpainful sides, and at multiple segmental levels (P = 0.038). Pain intensity and localization from experimental LBP were similar as during recalled clinical LBP episodes. In conclusion, unilateral and unisegmental experimental LBP exerts a generalized and widespread decrease in lumbar muscle activity during remission of recurrent LBP. This muscle response is consistent with previous observed patterns in healthy people subjected to the same experimental pain paradigm. It is striking that similar inhibitory patterns in response to pain could be observed, despite the presence of preexisting alterations in the lumbar musculature during remission of recurrent LBP. These results suggest that motor output can modify along the course of recurrent LBP.
authors.affiliation: Department of Rehabilitation Sciences and Physiotherapy, Ghent University, Ghent, Belgium;
authors.forename: Lieven
authors.initials: L
authors.lastname: Danneels
authors.affiliation: Department of Rehabilitation Sciences and Physiotherapy, Ghent University, Ghent, Belgium;
authors.forename: Barbara
authors.initials: B
authors.lastname: Cagnie
authors.affiliation: Department of Rehabilitation Sciences and Physiotherapy, Ghent University, Ghent, Belgium;
authors.forename: Roseline
authors.initials: R
authors.lastname: D'hooge
authors.affiliation: Department of Radiotherapy and Experimental Cancer Research, Ghent University Hospital, Ghent, Belgium;
authors.forename: Yves
authors.initials: Y
authors.lastname: De Deene
authors.affiliation: Department of Experimental Clinical and Health Psychology, Ghent University, Ghent, Belgium;
authors.forename: Geert
authors.initials: G
authors.lastname: Crombez
authors.affiliation: Department of Rehabilitation Sciences and Physiotherapy, Ghent University, Ghent, Belgium; Department of Physical and Rehabilitation Medicine, Ghent University Hospital, Ghent, Belgium; and.
authors.forename: Guy
authors.initials: G
authors.lastname: Vanderstraeten
authors.affiliation: Department of Physical Medicine and Orthopedic Surgery, Ghent University Hospital, Ghent, Belgium.
authors.forename: Thierry
authors.initials: T
authors.lastname: Parlevliet
authors.affiliation: Department of Rehabilitation Sciences and Physiotherapy, Ghent University, Ghent, Belgium;
authors.forename: Jessica
authors.initials: J
authors.lastname: Van Oosterwijck
mesh_terms: D000328:Adult; D015444:Exercise; D005260:Female; D006801:Humans; D017116:Low Back Pain / Q000503:physiopathology*; D008161:Lumbosacral Region / Q000502:physiology* / Q000503:physiopathology; D008279:Magnetic Resonance Imaging; D008297:Male; D008875:Middle Aged; D018482:Muscle, Skeletal / Q000502:physiology*; D059225:Nociception
keywords: experimental muscle pain; lumbar paraspinal muscles; muscle functional magnetic resonance imaging; muscle recruitment; recurrent low back pain