title: Paraspinal muscle asymmetry and fat infiltration in patients with symptomatic disc herniation.
abstract: To investigate asymmetry in size and composition of the multifidus and erector spinae in patients with posterolateral disc herniation and concordant radicular symptoms, and determine whether symptom duration is associated with degree of asymmetry.
  
  
  
  Thirty-three patients diagnosed with posterolateral disc herniation at L4-L5 verified on imaging and concordant leg pain were included. Multifidus and erector spinae cross-sectional area (CSA), functional cross-sectional area (FCSA, fat-free area), signal intensity and ratio of FCSA to total CSA were measured bilaterally from T 2-weighted axial magnetic resonance imaging (MRI) at L3-L4, L4-L5, L5-S1 and S1 levels.
  
  
  
  No side-to-side differences in multifidus CSA, FCSA, and ratio of FCSA/CSA reached statistical significance at any spinal level. The multifidus signal intensity at L5-S1 was significantly greater (more fatty infiltration) on the side of the disc herniation. The erector spinae FCSA (lean muscle mass) at L5-S1 was found to be significantly smaller on the side of the herniation and the ratio of FCSA/CSA was smaller (more fatty infiltration) on the side of the herniation at L4-L5 and L5-S1. The degree of muscle asymmetry was not associated with symptoms duration.
  
  
  
  There was no significant asymmetry of the multifidus at spinal level above, same or level below the disc herniation. Instead, variations in muscle composition were observed, with greater fat infiltration on the side and at spinal levels adjacent to the disc herniation. Muscle asymmetry was not correlated with symptom duration.
authors.affiliation: Common Spinal Disorders Research Group, Faculty of Rehabilitation Medicine, University of Alberta, 2-50 Corbett Hall, 8205, 114 Street, Edmonton, AB, T6G 2G4, Canada.
authors.forename: Maryse
authors.initials: M
authors.lastname: Fortin
authors.affiliation: National Centre for Spinal Disorders, Budapest, Hungary.
authors.forename: Àron
authors.initials: À
authors.lastname: Lazáry
authors.affiliation: National Centre for Spinal Disorders, Budapest, Hungary.
authors.forename: Peter Paul
authors.initials: PP
authors.lastname: Varga
authors.affiliation: Robert Jones and Agnes Hunt Orthopaedic Hospital, Keele University, Oswestry, Shropshire, UK.
authors.forename: Iain
authors.initials: I
authors.lastname: McCall
authors.affiliation: Common Spinal Disorders Research Group, Faculty of Rehabilitation Medicine, University of Alberta, 2-50 Corbett Hall, 8205, 114 Street, Edmonton, AB, T6G 2G4, Canada. michelec@ualberta.ca.
authors.forename: Michele C
authors.initials: MC
authors.lastname: Battié
mesh_terms: D000273:Adipose Tissue / Q000000981:diagnostic imaging / Q000473:pathology; D000328:Adult; D000368:Aged; D015331:Cohort Studies; D005260:Female; D006801:Humans; D007405:Intervertebral Disc Displacement / Q000000981:diagnostic imaging / Q000473:pathology; D008279:Magnetic Resonance Imaging; D008297:Male; D008875:Middle Aged; D064170:Paraspinal Muscles / Q000000981:diagnostic imaging / Q000473:pathology
keywords: Atrophy; Disc herniation; Erector spinae; Fatty infiltration; Multifidus