In children requiring botulinum toxin injections, improving supervisory procedures of injection sessions to reduce pain and improve the experience of this invasive procedure is needed. The intervention of medical clowns seems very interesting in this goal, but its effectiveness has not been proven within the botulinum toxin injections. The objective of the study is to evaluate in terms of profit the presence or absence of clowns during a session of botulinum toxins by determining their impact on pain and anxiety felt among children and their carers