title: Electrical impedance myography in spinal muscular atrophy: a longitudinal study.
abstract: BACKGROUND
  New approaches for assessing disease progression in spinal muscular atrophy (SMA) are needed. In this study, we evaluate whether electrical impedance myography (EIM) can detect disease progression in SMA compared with a group of healthy children of similar age.
  
  
  METHODS
  Twenty-eight children with SMA and 20 normal children underwent repeated EIM testing in four muscles at regular intervals for up to 3 years. An average rate of change of EIM was calculated for each subject and normalized to subcutaneous fat thickness and muscle girth.
  
  
  RESULTS
  Multiple EIM parameters showed a change in normal subjects over a mean of 16.7 months; however, no change was found in SMA patients over this period.
  
  
  CONCLUSIONS
  EIM could detect non-mass-dependent muscle maturation in healthy children. In contrast, the muscle in children with SMA, as measured by EIM, was virtually static, showing no evidence of growth or active deterioration.
authors.affiliation: Department of Neurology, Beth Israel Deaconess Medical Center, 330 Brookline Avenue, Boston, Massachusetts 02215, USA. srutkove@bidmc.harvard.edu
authors.forename: Seward B
authors.initials: SB
authors.lastname: Rutkove
authors.forename: Matt C
authors.initials: MC
authors.lastname: Gregas
authors.forename: Basil T
authors.initials: BT
authors.lastname: Darras
mesh_terms: D000293:Adolescent; D002648:Child; D002675:Child, Preschool; D017097:Electric Impedance; D004576:Electromyography; D005260:Female; D006801:Humans; D007223:Infant; D008137:Longitudinal Studies; D008297:Male; D053580:Muscle Strength / Q000502:physiology; D018482:Muscle, Skeletal / Q000000981:diagnostic imaging / Q000503:physiopathology*; D009134:Muscular Atrophy, Spinal / Q000473:pathology* / Q000503:physiopathology*; D018608:Ultrasonography, Doppler; D055815:Young Adult