title: Corticomotor control of lumbar multifidus muscles is impaired in chronic low back pain: concurrent evidence from ultrasound imaging and double-pulse transcranial magnetic stimulation.
abstract: Chronic low back pain (CLBP) is often associated with impaired control of deep trunk muscles and reorganization of the primary motor areas (M1). Precisely, functional changes of the lumbar multifidus muscles (MF) involved in spine stability may be of special interest in rehabilitation. Therefore, we tested MF corticomotor control using double transcranial magnetic stimulation (TMS) paradigms for the first time in this muscle and examined its link with MF volitional activation. Eleven individuals with lateralized CLBP and 13 pain-free participants were recruited. Ultrasound imaging enabled measurement of MF volitional isometric contraction in prone lying. TMS of MF M1 area was used to test hemispheric excitability and mechanisms in relation to motor programming, i.e., active motor threshold (AMT), amplitude of motor-evoked potentials and short-interval intracortical inhibition (SICI) and facilitation (SICF). In CLBP, SICI level was lower in the left hemisphere and MF volitional contraction was not related to AMT (M1 excitability), conversely to what was observed in the pain-free group. No other between-group difference was detected. These original findings support a plasticity of cortical maps controlling paravertebral muscles and likely including a different motor strategy for the control of MF. Changes of M1 function may thus underlie impaired motor control of lumbopelvic spine and pain persistence in CLBP.
authors.affiliation: Laboratory of Clinical Neuroscience and Neurostimulation, Neuroscience Division of the Centre de Recherche du CHU de Québec, RC-9800, 2705 Blvd. Laurier, Quebec City, QC, G1V 4G2, Canada.|Constance Lethbridge Rehabilitation Center Research Site of the CRIR, Montreal, QC, Canada.
authors.forename: Hugo
authors.initials: H
authors.lastname: Massé-Alarie
authors.affiliation: Laboratory of Clinical Neuroscience and Neurostimulation, Neuroscience Division of the Centre de Recherche du CHU de Québec, RC-9800, 2705 Blvd. Laurier, Quebec City, QC, G1V 4G2, Canada.
authors.forename: Louis-David
authors.initials: LD
authors.lastname: Beaulieu
authors.affiliation: Constance Lethbridge Rehabilitation Center Research Site of the CRIR, Montreal, QC, Canada.|School of Physical and Occupational Therapy, McGill University, Montreal, QC, Canada.
authors.forename: Richard
authors.initials: R
authors.lastname: Preuss
authors.affiliation: Laboratory of Clinical Neuroscience and Neurostimulation, Neuroscience Division of the Centre de Recherche du CHU de Québec, RC-9800, 2705 Blvd. Laurier, Quebec City, QC, G1V 4G2, Canada. cyril.schneider@rea.ulaval.ca.|Department of Rehabilitation, Faculty of Medicine, Université Laval, Québec City, QC, Canada. cyril.schneider@rea.ulaval.ca.
authors.forename: Cyril
authors.initials: C
authors.lastname: Schneider
mesh_terms: D000328:Adult; D059350:Chronic Pain / Q000000981:diagnostic imaging / Q000503:physiopathology; D004576:Electromyography / Q000379:methods; D005260:Female; D006801:Humans; D017116:Low Back Pain / Q000000981:diagnostic imaging* / Q000503:physiopathology*; D008159:Lumbar Vertebrae; D008297:Male; D008875:Middle Aged; D009044:Motor Cortex / Q000503:physiopathology*; D010147:Pain Measurement / Q000379:methods; D064170:Paraspinal Muscles / Q000000981:diagnostic imaging* / Q000503:physiopathology*; D050781:Transcranial Magnetic Stimulation / Q000379:methods*; D014463:Ultrasonography; D055815:Young Adult
keywords: Chronic low back pain; Intracortical inhibition and facilitation; Multifidus motor control; Primary motor cortex; Transcranial magnetic stimulation; Ultrasound imaging