title: Electrical impedance myography correlates with standard measures of ALS severity.
abstract: BACKGROUND
  Electrical impedance myography (EIM) can be used to assess amyotrophic lateral sclerosis (ALS) progression. The relationship between EIM values and standard assessment measures, however, is unknown.
  
  
  METHODS
  EIM 50 kHz phase data from 60 subjects who participated in a longitudinal natural history study of ALS were correlated with handheld dynamometry (HHD), the ALS Functional Rating Scale-Revised (ALSFRS-R) score, and motor unit number estimation (MUNE).
  
  
  RESULTS
  Moderate strength correlations between EIM parameters and HHD were observed for both whole-body and individual upper and lower extremity values. Similarly, moderate strength correlations were observed between EIM and ALSFRS-R upper and lower extremity subscores, but not total ALSFRS-R scores. MUNE correlated significantly with single muscle EIM data but not with whole body or upper or lower extremity values.
  
  
  CONCLUSIONS
  These results support the concept that EIM can serve as a meaningful measure of disease severity in ALS.
authors.affiliation: Department of Neurology, Beth Israel Deaconess Medical Center, 330 Brookline Avenue, TCC-810, Boston, Massachusetts, USA, 02215.
authors.forename: Seward B
authors.initials: SB
authors.lastname: Rutkove
authors.forename: James B
authors.initials: JB
authors.lastname: Caress
authors.forename: Michael S
authors.initials: MS
authors.lastname: Cartwright
authors.forename: Ted M
authors.initials: TM
authors.lastname: Burns
authors.forename: Judy
authors.initials: J
authors.lastname: Warder
authors.forename: William S
authors.initials: WS
authors.lastname: David
authors.forename: Namita
authors.initials: N
authors.lastname: Goyal
authors.forename: Nicholas J
authors.initials: NJ
authors.lastname: Maragakis
authors.forename: Michael
authors.initials: M
authors.lastname: Benatar
authors.forename: Khema R
authors.initials: KR
authors.lastname: Sharma
authors.forename: Pushpa
authors.initials: P
authors.lastname: Narayanaswami
authors.forename: Elizabeth M
authors.initials: EM
authors.lastname: Raynor
authors.forename: Mary Lou
authors.initials: ML
authors.lastname: Watson
authors.forename: Jeremy M
authors.initials: JM
authors.lastname: Shefner
mesh_terms: D000368:Aged; D000690:Amyotrophic Lateral Sclerosis / Q000175:diagnosis* / Q000503:physiopathology*; D018450:Disease Progression; D017097:Electric Impedance; D019054:Evoked Potentials, Motor / Q000502:physiology; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D053581:Muscle Strength Dynamometer; D018482:Muscle, Skeletal / Q000503:physiopathology*; D009213:Myography / Q000379:methods* / Q000592:standards
keywords: ALSFRS-R; amyotrophic lateral sclerosis; biomarkers; electrical impedance myography; handheld dynamometry