title: Ultrasound assessment of bilateral longus colli muscles in subjects with chronic bilateral neck pain.
abstract: OBJECTIVE
  The aim of this study was to investigate bilateral differences in the cross-sectional area (CSA) and shape ratio of the longus colli muscle between subjects with mechanical neck pain and healthy controls.
  
  
  METHODS
  A case-control cohort study was conducted. Bilateral ultrasound images of the longus colli muscle at the thyroid (C5-C6) level were conducted in 20 patients with mechanical bilateral chronic neck pain and 20 controls by an assessor blinded to the subjects' condition. CSA, anterior-posterior dimension (APD), lateral dimension (LD), and shape ratio (LD/APD) were measured.
  
  
  RESULTS
  The intraclass correlation coefficients (3,1) were above 0.86 for within-day and above 0.81 for between-day intraexaminer reliability. Patients with mechanical neck pain showed bilateral smaller CSA (P < 0.001) and APD (P = 0.004) as compared with controls. Muscle shape and LD were not different between groups (P = 0.092 and P = 0.963, respectively). Women exhibited smaller bilateral CSA as compared with men (P < 0.01). CSA was negatively associated with self-reported disability, whereas APD was negatively associated with intensity of neck pain: the greater the self-reported disability or the pain intensity, the smaller the bilateral CSA or APD of the longus colli muscle.
  
  
  CONCLUSIONS
  The longus colli muscle exhibited smaller bilateral CSA and APD, but not LD and shape ratio, in subjects with bilateral chronic neck pain as compared with healthy controls. Reduced CSA was negatively associated with self-reported disability and APD was negatively associated with the intensity of pain.
authors.affiliation: Physiotherapy Department, University of Social Welfare and Rehabilitation Sciences, Tehran, Iran.
authors.forename: Khodabakhsh
authors.initials: K
authors.lastname: Javanshir
authors.forename: Asghar
authors.initials: A
authors.lastname: Rezasoltani
authors.forename: Mohammad Ali
authors.initials: MA
authors.lastname: Mohseni-Bandpei
authors.forename: Mohsen
authors.initials: M
authors.lastname: Amiri
authors.forename: Ricardo
authors.initials: R
authors.lastname: Ortega-Santiago
authors.forename: César
authors.initials: C
authors.lastname: Fernández-de-Las-Peñas
mesh_terms: D000328:Adult; D016022:Case-Control Studies; D002574:Cervical Vertebrae; D002908:Chronic Disease; D015331:Cohort Studies; D005260:Female; D019416:Head Movements; D006801:Humans; D008297:Male; D009334:Neck Muscles / Q000000981:diagnostic imaging* / Q000473:pathology / Q000503:physiopathology; D019547:Neck Pain / Q000000981:diagnostic imaging* / Q000209:etiology / Q000473:pathology; D010147:Pain Measurement; D016059:Range of Motion, Articular; D015203:Reproducibility of Results; D012737:Sex Factors; D014463:Ultrasonography; D055815:Young Adult