title: Smudging of the Motor Cortex Is Related to the Severity of Low Back Pain.
abstract: METHODS
  Cross-sectional design.
  
  
  OBJECTIVE
  Here we aimed to determine whether motor cortical reorganization in low back pain (LBP) can be identified using noninvasive surface electromyographic (EMG) recordings of back muscles at different lumbar levels, and whether cortical reorganization is related to clinical features of LBP.
  
  
  BACKGROUND
  Reorganization of motor regions of the brain may contribute to altered motor control, pain, and disability in chronic LBP. However, data have been limited by the need for invasive recordings of back muscle myoelectric activity. The relationship between altered cortical organization and clinical features of LBP remains unclear.
  
  
  METHODS
  In 27 individuals with recurrent, nonspecific LBP and 23 pain-free controls, we mapped the motor cortical representation of the paraspinal muscles using transcranial magnetic stimulation in conjunction with noninvasive surface EMG recordings at L3 and L5 levels. Clinical measures of pain severity, location, and duration were made.
  
  
  RESULTS
  The results demonstrate a loss of discrete motor cortical organization of the paraspinal muscles in chronic LBP that can be identified using noninvasive EMG recordings. A loss of discrete cortical organization was clearer when surface electrodes were positioned at L3 rather than L5. A novel finding was that altered motor cortical organization (number of discrete peaks and map volume) was associated with the severity and location of LBP.
  
  
  CONCLUSIONS
  These data suggest that surface EMG positioned at L3 is appropriate for the identification of changes in the motor cortex in LBP. Furthermore, our data have implications for treatment strategies that aim to restore cortical organization in LBP.
  
  
  METHODS
  2.
authors.affiliation: School of Science and Health, University of Western Sydney, Campbelltown, New South Wales, Australia.|The University of Queensland, NHMRC Centre of Clinical Research Excellence in Spinal Pain, Injury and Health and School of Health and Rehabilitation Sciences, Brisbane, Queensland, Australia.
authors.forename: Siobhan M
authors.initials: SM
authors.lastname: Schabrun
authors.affiliation: The University of Queensland, NHMRC Centre of Clinical Research Excellence in Spinal Pain, Injury and Health and School of Health and Rehabilitation Sciences, Brisbane, Queensland, Australia.
authors.forename: Edith L
authors.initials: EL
authors.lastname: Elgueta-Cancino
authors.affiliation: The University of Queensland, NHMRC Centre of Clinical Research Excellence in Spinal Pain, Injury and Health and School of Health and Rehabilitation Sciences, Brisbane, Queensland, Australia.
authors.forename: Paul W
authors.initials: PW
authors.lastname: Hodges
mesh_terms: D000328:Adult; D003430:Cross-Sectional Studies; D004576:Electromyography / Q000379:methods*; D005260:Female; D006801:Humans; D017116:Low Back Pain / Q000175:diagnosis* / Q000503:physiopathology*; D008297:Male; D009044:Motor Cortex / Q000503:physiopathology*; D064170:Paraspinal Muscles / Q000503:physiopathology; D012720:Severity of Illness Index; D050781:Transcranial Magnetic Stimulation / Q000379:methods*; D055815:Young Adult