title: Muscle volume alterations in spastic muscles immediately following botulinum toxin type-A treatment in children with cerebral palsy.
abstract: OBJECTIVE
  With evidence for an atrophic effect of botulinum toxin type A (BoNT-A) documented in typically developing muscles, this study investigated the immediate morphological alterations of muscles in children with cerebral palsy (CP) after BoNT-A treatment.
  
  
  METHODS
  Fifteen children (10 males, five females; age range 5-11y, mean age 8y 5mo, SD 1y 10mo) with spastic diplegic CP [Gross Motor Function Classification System Levels I (n=9) and II (n=6)] receiving BoNT-A injections for spasticity management were included. None of the children was a first-time receiver of BoNT-A. Magnetic resonance imaging and Mimics software assessed muscle volume, timed 2 weeks before and 5 weeks after injection. All participants received BoNT-A bilaterally to the gastrocnemius muscle, and five participants also received BoNT-A bilaterally to the medial hamstring muscles. Functional assessment measures used were the 6-Minute Walk Test (6-MWT), the Timed Up and Go (TUG) test, and hand-held dynamometry.
  
  
  RESULTS
  Whilst total muscle group volume of the injected muscle group remained unchanged, a 4.47% decrease in the injected gastrocnemius muscle volume (p=0.01) and a 3.96% increase in soleus muscle volume (p=0.02) was evident following BoNT-A. There were no statistically significant changes in function after BoNT-A as assessed by the TUG. There was also no statistically significant change in distance covered in the 6-MWT. Muscle strength, as assessed using hand-held dynamometry was also not statistically different after BoNT-A treatment.
  
  
  CONCLUSIONS
  Muscle volume decreases were observed in the injected muscle (gastrocnemius), with synergistic muscle hypertrophy that appeared to compensate for this decrement. The 4% to 5% decrease in the volume of BoNT-A injected muscles are not dramatic in comparison to reports in recent animal studies, and are a positive indication for BoNT-A, particularly as it also did not negatively alter function.
authors.affiliation: School of Sport Science, Exercise & Health, The University of Western Australia, Perth, WA, Australia. Sian.Williams@health.wa.gov.au
authors.forename: Sîan A
authors.initials: SA
authors.lastname: Williams
authors.forename: Siobhan
authors.initials: S
authors.lastname: Reid
authors.forename: Catherine
authors.initials: C
authors.lastname: Elliott
authors.forename: Peter
authors.initials: P
authors.lastname: Shipman
authors.forename: Jane
authors.initials: J
authors.lastname: Valentine
mesh_terms: D019274:Botulinum Toxins, Type A / Q000008:administration & dosage / Q000494:pharmacology / Q000627:therapeutic use*; D002547:Cerebral Palsy / Q000188:drug therapy* / Q000473:pathology / Q000503:physiopathology; D002648:Child; D002675:Child, Preschool; D005260:Female; D006801:Humans; D007273:Injections, Intramuscular; D035002:Lower Extremity; D008279:Magnetic Resonance Imaging; D008297:Male; D009119:Muscle Contraction / Q000187:drug effects; D053580:Muscle Strength / Q000187:drug effects*; D018908:Muscle Weakness / Q000188:drug therapy; D018482:Muscle, Skeletal / Q000187:drug effects* / Q000473:pathology* / Q000503:physiopathology; D009929:Organ Size / Q000187:drug effects; D016896:Treatment Outcome
chemical_list: D019274:Botulinum Toxins, Type A