Botulinum toxin injections : Botulinum toxin is a neurotoxin produced by the clostridium botulinum bacteria. Seven different serotypes exist but only the A and B serotypes are used in clinical practice. Botulinum toxin blocks the presynaptic release of neurotransmitter at the neuromuscular junction. Focal transitory paralysis thus occurs in the injected muscle. Its action lasts on average 3 months in striated skeletal muscle. The effect of BTI in the upper limb depends on the parameters studied. A meta-analysis carried out by Foley et al, 2013 showed a relatively large effect size for the reduction of impairment and the improvement of passive function. However, there was only a small effect size for the improvement of functions such as prehension. This confirms the results of a previous study (Sheean et al, 2010) which showed that the effect of BTI in the upper limb was only significant for the reduction of impairment or the improvement of passive function, but not active function.