title: Shear wave elastography reveals different degrees of passive and active stiffness of the neck extensor muscles.
abstract: OBJECTIVE
  The neck extensor muscles contribute to spinal support and posture while performing head and neck motion. Muscle stiffness relates to passive elasticity (support) and active tensioning (posture and movement) of muscle. It was hypothesized that support and motion requirements are reflected in the distribution of stiffness between superficial and deep neck extensor muscles.
  
  
  METHODS
  In ten healthy participants, shear modulus (stiffness) of five neck extensor muscles was determined in prone at rest and during isometric head lift at three intensities using shear wave elastography.
  
  
  RESULTS
  Shear modulus differed between muscles (P < 0.001), and was larger for the deeper muscles: (median (interquartile range)) trapezius 7.7 kPa (4.4), splenius capitis 6.5 kPa (2.5), semispinalis capitis 8.9 kPa (2.8), semispinalis cervicis 9.5 kPa (2.5), multifidus 14.9 kPa (1.4). Shear modulus differed between the resting condition and head lift (P < 0.001) but not between levels of head lift intensity.
  
  
  CONCLUSIONS
  Shear wave elastography revealed highest passive and active stiffness of the deep neck extensor muscles most close to the spine. The highest active increase of stiffness during the head lift was found in the semispinalis cervicis muscle. The non-invasive, clinically applicable estimates of muscle stiffness have potential for the assessment of muscular changes associated with neck pain/injury.
authors.affiliation: Schmerzmedizin, Klinik für Anästhesiologie, University Medical Center, Göttingen, Germany. angela.dieterich@bccn.uni-goettingen.de.|Schmerzmedizin, Klinik für Anästhesiologie, University Medical Center, Robert-Koch-Str.40, 37075, Göttingen, Germany. angela.dieterich@bccn.uni-goettingen.de.
authors.forename: Angela V
authors.initials: AV
authors.lastname: Dieterich
authors.affiliation: Laboratory "Movement, Interactions, Performance" (EA 4334), Faculty of Sport Sciences, University of Nantes, Nantes, France.|Faculty of Human Movement, University of Lisboa, Cruz Quebrada-Dafundo, Portugal.
authors.forename: Ricardo J
authors.initials: RJ
authors.lastname: Andrade
authors.affiliation: Laboratory "Movement, Interactions, Performance" (EA 4334), Faculty of Sport Sciences, University of Nantes, Nantes, France.|School of Physiotherapy (IFM3R), Nantes, France.
authors.forename: Guillaume
authors.initials: G
authors.lastname: Le Sant
authors.affiliation: Centre of Precision Rehabilitation for Spinal Pain (CPR Spine), School of Sport, Exercise and Rehabilitation Sciences, College of Life and Environmental Sciences, University of Birmingham, Birmingham, UK.
authors.forename: Deborah
authors.initials: D
authors.lastname: Falla
authors.affiliation: Schmerzmedizin, Klinik für Anästhesiologie, University Medical Center, Göttingen, Germany.
authors.forename: Frank
authors.initials: F
authors.lastname: Petzke
authors.affiliation: Laboratory "Movement, Interactions, Performance" (EA 4334), Faculty of Sport Sciences, University of Nantes, Nantes, France.|NHMRC Centre of Clinical Research Excellence in Spinal Pain, Injury and Health, School of Health and Rehabilitation Sciences, The University of Queensland, Brisbane, Australia.
authors.forename: François
authors.initials: F
authors.lastname: Hug
authors.affiliation: Laboratory "Movement, Interactions, Performance" (EA 4334), Faculty of Sport Sciences, University of Nantes, Nantes, France.
authors.forename: Antoine
authors.initials: A
authors.lastname: Nordez
mesh_terms: D000293:Adolescent; D000328:Adult; D004548:Elasticity; D054459:Elasticity Imaging Techniques; D005260:Female; D006801:Humans; D008297:Male; D053580:Muscle Strength; D009334:Neck Muscles / Q000000981:diagnostic imaging* / Q000502:physiology; D011187:Posture
keywords: Cervical spine; Muscle activation; Neck; Shear modulus; Shear wave elastography; Synergist; Ultrasound