title: Quantifying passive muscle stiffness in children with and without cerebral palsy using ultrasound shear wave elastography.
abstract: OBJECTIVE
  The aim of this study was to compare passive muscle stiffness in children with cerebral palsy (CP) and children with typical development using a novel ultrasound technique: ultrasound shear wave elastography (SWE).
  
  
  METHODS
  We conducted a prospective study of 13 children with CP (six females and seven males, median age 5y 1mo [interquartile range 4y 4mo-7y 8mo]) and 13 children with typical development (six females and seven males, median age 5y 3mo [interquartile range 4y 4mo-9y 4mo]). Demographic information and physical exam measurements were obtained in addition to shear modulus measurements (passive muscle stiffness) of the lateral gastrocnemius muscle at 20° plantar flexion, 10° plantar flexion, and 0° plantar flexion using SWE.
  
  
  RESULTS
  Children with CP had significantly greater shear modulus measurements at all three foot positions (p<0.050). When the shear modulus values were normalized to the baseline value for each child, there was no significant difference between the two groups.
  
  
  CONCLUSIONS
  Passive muscle stiffness, measured without the influence of spasticity, is greater in children with CP than in children with typical development when a muscle is at slack and at stretch. When shear modulus was normalized, the results indicate that muscle in children in both groups responds similarly to passive stretch. Further work includes evaluating effect of botulinum toxin on passive muscle properties.
authors.affiliation: Department of Physical Medicine and Rehabilitation, Mayo Clinic College of Medicine, Rochester, MN, USA.|Department of Neurology, Mayo Clinic College of Medicine, Rochester, MN, USA.|Department of Pediatric and Adolescent Medicine, Mayo Clinic College of Medicine, Rochester, MN, USA.
authors.forename: Joline E
authors.initials: JE
authors.lastname: Brandenburg
authors.affiliation: Medical Scientist Training Program, Mayo Graduate School, Mayo Clinic College of Medicine, Rochester, MN, USA.
authors.forename: Sarah F
authors.initials: SF
authors.lastname: Eby
authors.affiliation: Department of Radiology, Mayo Clinic College of Medicine, Rochester, MN, USA.
authors.forename: Pengfei
authors.initials: P
authors.lastname: Song
authors.affiliation: Department of Physiology and Biomedical Engineering, Mayo Clinic College of Medicine, Rochester, MN, USA.
authors.forename: Shirley
authors.initials: S
authors.lastname: Kingsley-Berg
authors.affiliation: Division of Biomedical Sciences and Informatics, Mayo Clinic College of Medicine, Rochester, MN, USA.
authors.forename: William
authors.initials: W
authors.lastname: Bamlet
authors.affiliation: Department of Physiology and Biomedical Engineering, Mayo Clinic College of Medicine, Rochester, MN, USA.
authors.forename: Gary C
authors.initials: GC
authors.lastname: Sieck
authors.affiliation: Department of Physiology and Biomedical Engineering, Mayo Clinic College of Medicine, Rochester, MN, USA.|Division of Orthopedic Research, Mayo Clinic College of Medicine, Mayo Clinic, Rochester, MN, USA.
authors.forename: Kai-Nan
authors.initials: KN
authors.lastname: An
mesh_terms: D000843:Ankle Joint / Q000503:physiopathology*; D002547:Cerebral Palsy / Q000000981:diagnostic imaging*; D002648:Child; D002675:Child, Preschool; D054459:Elasticity Imaging Techniques / Q000379:methods*; D005260:Female; D006801:Humans; D008297:Male; D009128:Muscle Spasticity / Q000000981:diagnostic imaging*; D018482:Muscle, Skeletal / Q000000981:diagnostic imaging*; D016059:Range of Motion, Articular / Q000502:physiology*