The effect of botulinum toxin A on gastrocnemius length: magnitude and duration of response

Dev Med Child Neurol. 1999 Apr;41(4):226-32. doi: 10.1017/s0012162299000493.


Thirty-nine ambulant children (22 with hemiplegia, 17 with diplegia) with spastic cerebral palsy receiving isolated gastrocnemius muscle injection with botulinum toxin A were studied prospectively. The children had a mean age of 6 years (range 3 to 13 years). Measurement of gastrocnemius muscle length was used to estimate the dynamic component of each child's spasticity and to quantify the response. There was a strong correlation between the dynamic component of spasticity before injection and the corresponding magnitude of the response after injection. Children undergoing repeated injections showed similar correlations. A strong correlation was found between the duration of response and the dynamic component. Children with hemiplegia showed twice the duration for a given dynamic component compared with those with diplegia when injected with the same total dose per unit body weight. Long-term lengthening did not occur for the cohort, although some patients showed a response at a 12-month follow-up. By delaying shortening, the injections may have a role in delaying the need for surgery. Injections were well tolerated with few side effects.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adolescent
  • Botulinum Toxins, Type A / adverse effects
  • Botulinum Toxins, Type A / pharmacology
  • Botulinum Toxins, Type A / therapeutic use*
  • Child
  • Child, Preschool
  • Female
  • Hemiplegia / drug therapy
  • Hemiplegia / physiopathology
  • Humans
  • Male
  • Muscle Contraction / drug effects
  • Muscle Relaxation / drug effects*
  • Muscle, Skeletal / drug effects*
  • Neuromuscular Agents / adverse effects
  • Neuromuscular Agents / pharmacology
  • Neuromuscular Agents / therapeutic use*
  • Paralysis / drug therapy*
  • Paralysis / physiopathology*
  • Prospective Studies
  • Time Factors
  • Treatment Outcome


  • Neuromuscular Agents
  • Botulinum Toxins, Type A