title: Evaluation of Stiffness of the Spastic Lower Extremity Muscles in Early Spinal Cord Injury by Acoustic Radiation Force Impulse Imaging.
abstract: OBJECTIVE
  To investigate intrinsic viscoelastic changes using shear wave velocities (SWVs) of spastic lower extremity muscles in patients with early spinal cord injury (SCI) via acoustic radiation force impulse (ARFI) imaging and to evaluate correlation between the SWV values and spasticity.
  
  
  METHODS
  Eighteen patients with SCI within 3 months and 10 healthy adults participated. We applied the ARFI technique to measure SWV of gastrocnemius muscle (GCM) and long head of biceps femoris muscle. Spasticity of ankle and knee joint was assessed by original Ashworth Scale.
  
  
  RESULTS
  Ten patients with SCI had spasticity. Patients with spasticity had significantly faster SWV for GCM and biceps femoris muscle than those without spasticity (Mann-Whitney U test, p=0.007 and p=0.008) and normal control (p=0.011 and p=0.037, respectively). The SWV values of GCM correlated with the ankle spasticity (Spearman rank teat, p=0.026). There was significant correlation between the SWV values for long head of biceps femoris muscle and knee spasticity (Spearman rank teat, p=0.022).
  
  
  CONCLUSIONS
  ARFI demonstrated a difference in muscle stiffness in the GCM between patients with spastic SCI and those without spasticity. This finding suggested that stiffness of muscles increased in spastic lower extremity of early SCI patients. ARFI imaging is a valuable tool for noninvasive assessment of the stiffness of the spastic muscle and has the potential to identify pathomechanical changes of the tissue associated with SCI.
authors.affiliation: Department of Rehabilitation Medicine, Chungnam National University School of Medicine, Daejeon, Korea.
authors.forename: Kang Hee
authors.initials: KH
authors.lastname: Cho
authors.affiliation: Department of Rehabilitation Medicine, Chungnam National University School of Medicine, Daejeon, Korea.
authors.forename: Jin Hee
authors.initials: JH
authors.lastname: Nam
keywords: Muscle spasticity; Spinal cord injuries; Ultrasonography