title: Electrical impedance myography in Duchenne muscular dystrophy and healthy controls: A multicenter study of reliability and validity.
abstract: BACKGROUND
  Electrical impedance myography (EIM) is a non-invasive, painless, objective technique to quantify muscle pathology.
  
  
  METHODS
  We measured EIM in 8 arm and leg muscles in 61 boys with Duchenne muscular dystrophy (DMD) and 31 healthy boys, ages 3-12 years, at 5 centers. We determined the reliability of EIM and compared results in boys with DMD to controls and to 6-minute walk distance (6MWD), North Star Ambulatory Assessment (NSAA), timed functional tests (TFTs), and strength (hand-held dynamometry).
  
  
  RESULTS
  EIM was well tolerated and had good inter- and intrarater reliability (intraclass correlation coefficient 0.81-0.96). The averaged EIM phase value from all muscles was higher (P < 0.001) in controls (10.45 ± 2.29) than boys with DMD (7.31 ± 2.23), and correlated (P ≤ 0.001) with 6MWD (r = 0.55), NSAA (r = 0.66), TFTs (r = -0.56), and strength (r = 0.44).
  
  
  CONCLUSIONS
  EIM is a reliable and valid measure of disease severity in DMD. Longitudinal studies comparing EIM with other assessments over time in DMD are warranted.
authors.affiliation: Department of Neurology, Washington University School of Medicine, 660 South Euclid Avenue, Box 8111, St. Louis, Missouri, 63110, USA.|Department of Pediatrics, Washington University School of Medicine, St. Louis, Missouri, USA.
authors.forename: Craig M
authors.initials: CM
authors.lastname: Zaidman
authors.affiliation: Skulpt, Inc, Boston, Massachusetts, USA.
authors.forename: Lucy L
authors.initials: LL
authors.lastname: Wang
authors.affiliation: Department of Neurology, Washington University School of Medicine, 660 South Euclid Avenue, Box 8111, St. Louis, Missouri, 63110, USA.|Department of Pediatrics, Washington University School of Medicine, St. Louis, Missouri, USA.
authors.forename: Anne M
authors.initials: AM
authors.lastname: Connolly
authors.affiliation: Department of Neurology, Washington University School of Medicine, 660 South Euclid Avenue, Box 8111, St. Louis, Missouri, 63110, USA.
authors.forename: Julaine
authors.initials: J
authors.lastname: Florence
authors.affiliation: Department of Pediatrics, Cincinnati Children's Hospital Medical Center, Cincinnati, Ohio, USA.
authors.forename: Brenda L
authors.initials: BL
authors.lastname: Wong
authors.affiliation: Department of Pediatrics and Neurology, University of Colorado, Denver, Colorado, USA.
authors.forename: Julie A
authors.initials: JA
authors.lastname: Parsons
authors.affiliation: Department of Rehabilitation Medicine, University of Washington, Seattle, Washington, USA.
authors.forename: Susan
authors.initials: S
authors.lastname: Apkon
authors.affiliation: Department of Neurology, Massachusetts General Hospital, Boston, Massachusetts, USA.
authors.forename: Namita
authors.initials: N
authors.lastname: Goyal
authors.affiliation: DART Therapeutics, Inc, Stockbridge, Massachusetts, USA.
authors.forename: Eugene
authors.initials: E
authors.lastname: Williams
authors.affiliation: DART Therapeutics, Inc, Stockbridge, Massachusetts, USA.
authors.forename: Diana
authors.initials: D
authors.lastname: Escolar
authors.affiliation: Department of Neurology, Beth Israel Deaconess Medical Center, Boston, Massachusetts, USA.
authors.forename: Seward B
authors.initials: SB
authors.lastname: Rutkove
authors.affiliation: Skulpt, Inc, Boston, Massachusetts, USA.
authors.forename: Jose L
authors.initials: JL
authors.lastname: Bohorquez
mesh_terms: D000367:Age Factors; D002648:Child; D002675:Child, Preschool; D017097:Electric Impedance; D005260:Female; D006801:Humans; D008297:Male; D053580:Muscle Strength / Q000502:physiology*; D053581:Muscle Strength Dynamometer; D018482:Muscle, Skeletal / Q000503:physiopathology*; D020388:Muscular Dystrophy, Duchenne / Q000473:pathology* / Q000503:physiopathology*; D009213:Myography; D012372:ROC Curve; D015203:Reproducibility of Results; D012720:Severity of Illness Index
keywords: Duchenne muscular dystrophy; biomarker; children; electrical impedance myography; myopathy