title: No change in calf muscle passive stiffness after botulinum toxin injection in children with cerebral palsy.
abstract: OBJECTIVE
  Stiffness and shortening of the calf muscle due to neural or mechanical factors can profoundly affect motor function. The aim of this study was to investigate non-neurally mediated calf-muscle tightness in children with cerebral palsy (CP) before and after botulinum toxin type A (BoNT-A) injection.
  
  
  METHODS
  Sixteen children with spastic CP (seven females, nine males; eight at Gross Motor Function Classification System level I, eight at level II; age range 4-10 y) and calf muscle spasticity were tested before and during the pharmaceutically active phase after injection of BoNT-A. Measures of passive muscle compliance and viscoelastic responses, hysteresis, and the gradient of the torque-angle curve were computed and compared before and after injection.
  
  
  RESULTS
  Although there was a slight, but significant increase in ankle range of motion after BoNT-A injection and a small, significant decrease in the torque required to achieve plantigrade and 5° of dorsiflexion, no significant difference in myotendinous stiffness or hysteresis were detected after BoNT-A injection.
  
  
  CONCLUSIONS
  Despite any effect on neurally mediated responses, the compliance of the calf muscle was not changed and the muscle continued to offer significant resistance to passive motion of the ankle. These findings suggest that additional treatment approaches are required to supplement the effects of BoNT-A injections when managing children with calf muscle spasticity.
authors.affiliation: Clinical Rehabilitation Sciences Research Group, Faculty of Health Sciences, The University of Sydney, Lidcombe, NSW, Australia.
authors.forename: Adel A A
authors.initials: AA
authors.lastname: Alhusaini
authors.forename: Jack
authors.initials: J
authors.lastname: Crosbie
authors.forename: Roberta B
authors.initials: RB
authors.lastname: Shepherd
authors.forename: Catherine M
authors.initials: CM
authors.lastname: Dean
authors.forename: Adam
authors.initials: A
authors.lastname: Scheinberg
mesh_terms: D019274:Botulinum Toxins, Type A / Q000494:pharmacology / Q000627:therapeutic use*; D002547:Cerebral Palsy / Q000188:drug therapy* / Q000503:physiopathology*; D002648:Child; D002675:Child, Preschool; D004576:Electromyography / Q000379:methods; D005260:Female; D006801:Humans; D007273:Injections, Intramuscular / Q000379:methods; D007596:Joints / Q000187:drug effects; D008297:Male; D009128:Muscle Spasticity / Q000188:drug therapy / Q000209:etiology; D018482:Muscle, Skeletal / Q000187:drug effects* / Q000503:physiopathology*; D009465:Neuromuscular Agents / Q000494:pharmacology / Q000627:therapeutic use*; D011446:Prospective Studies; D016059:Range of Motion, Articular / Q000187:drug effects; D018709:Statistics, Nonparametric; D019415:Torque
chemical_list: D009465:Neuromuscular Agents; D019274:Botulinum Toxins, Type A