title: Muscle changes in brachial plexus birth injury with elbow flexion contracture: an MRI study.
abstract: BACKGROUND
  Muscle pathology of the arm and forearm in brachial plexus birth injury (BPBI) with elbow flexion contracture has not been evaluated with MRI.
  
  
  OBJECTIVE
  To determine whether limited range of motion of the elbow in BPBI is correlated with specific patterns of muscular pathology.
  
  
  METHODS
  For 15 BPBI patients, total active motion (TAM) of the elbow (extension-flexion) and the forearm (pronation-supination) were measured. MRI of the elbow joints and musculature allowed assessment of elbow congruency. Fatty infiltration and size reduction of the muscles were graded semiquantitatively.
  
  
  RESULTS
  Mean TAM of the elbow was 113 degrees (50 degrees-140 degrees) and that of the forearm 91 degrees (10 degrees-165 degrees). The greater the size reduction of the brachioradialis muscle, the more diminished was elbow TAM. The more extensive the BPBI and muscle pathology of the pronator teres muscle, the more limited was the TAM of the forearm. Pathology of the supinator and brachialis muscles was evident in every patient.
  
  
  CONCLUSIONS
  Extensive BPBI may result in marked limitation of TAM. Elbow flexion contracture seems to be caused mainly by brachialis muscle pathology. Prosupination of the forearm is better preserved when the pronator teres is not severely affected. MRI can reliably show the extent of muscle pathology in BPBI.
authors.affiliation: Helsinki Medical Imaging Center, University of Helsinki, 00029 Helsinki, Finland. tiina.poyhia@hus.fi
authors.forename: Tiina H
authors.initials: TH
authors.lastname: Pöyhiä
authors.forename: Mika P
authors.initials: MP
authors.lastname: Koivikko
authors.forename: Jari I
authors.initials: JI
authors.lastname: Peltonen
authors.forename: Mikko O
authors.initials: MO
authors.lastname: Kirjavainen
authors.forename: Antti E
authors.initials: AE
authors.lastname: Lamminen
authors.forename: A Yrjänä
authors.initials: AY
authors.lastname: Nietosvaara
mesh_terms: D000293:Adolescent; D001720:Birth Injuries / Q000150:complications / Q000175:diagnosis*; D020516:Brachial Plexus Neuropathies / Q000150:complications / Q000175:diagnosis*; D002648:Child; D002675:Child, Preschool; D003286:Contracture / Q000175:diagnosis*; D004551:Elbow Joint / Q000294:innervation / Q000473:pathology*; D005260:Female; D006801:Humans; D008279:Magnetic Resonance Imaging / Q000379:methods*; D008297:Male; D018482:Muscle, Skeletal / Q000294:innervation / Q000473:pathology*; D009135:Muscular Diseases / Q000175:diagnosis* / Q000209:etiology