Spasticity is a poorly defined concept of increasing resistance against fast movements. It comprises a static picture of lost control on reflexes, and primitive reflexes are unmasked. This view is too simple. Reflexes can be modulated by the individual over time, which means, that increase and decrease are possible. Also, some control on reflex activity can be regained. Especially the affection of the sensory parallel to the motor pathways can explain the difficulties to build up a better control. A lot of time and movement experience are required, reflected in developmental delay and improvement of spasticity in at least some patients over time.