A randomised controlled trial to determine the optimum frequency of Botulinum Toxin injections to the calf in children with cerebral palsy

Cerebral Palsy (CP) is a disorder affecting around 2 in 1000 live births. Commonly, children with CP have spasticity in their muscles causing stiffness. When Botox (Botulinum Toxin A) is injected into a spastic muscle, it helps it to relax for around 3 months, after which the effect begins to wear off. During this relaxed time, the muscle is able to exercise through a greater range, helping to prevent contractures from forming. Botox is therefore used to both reduce spasticity in the short term, and to slow or prevent the development of contractures in the long term. This in turn, assists to delay corrective orthopaedic surgery until the later childhood years when surgical outcomes are more predictable and longer lasting. Currently, the most important clinical question is how often Botox should be used. More regular injections may provide additional time that the effects of Botox are working, and muscle contractures could be delayed more effectively. The aim of this study is to compare over a two-year period, the effects of Botox injections once a year compared to 3 times a year (every four months). The main measure will be the rate of development of contractures over the two years. Measurements (such as calf strength, questionnaires and blood tests) will also be made to determine whether either program negatively affects the muscle, whether the children in either group have a different level of function or quality of life and whether either program leads to the Botox having a reduced effect over time.