Hi
Children with Athetoid Cerebral Palsy have lack of proximal fixation and Lack of dissociation in addition to poor trunk control. They usually use ATNR to perform movement and they have a problem in using more than one postural pattern of movement at the same time.
So, I suggest the following:
1- Start your session in sitting position to break up the dominant postural pattern of movement.
2- Apply joint compression to the upper limbs
2- Facilitate dissociation of upper limbs from each other, then upper limbs from trunk.
3- From sitting position on a roll encourage the child to push a GymBall in the midline
4- From the previous position encourage the child to pick up some toys from the floor in the mid line
5- Then from this position take the child directly from the roll to a nearby GymBall and do some bouncing in sitting position then move him to the sides, forward and backward.
6- Do pelvic dissociation on the GymBall ( you will need an assistant to hold the child's hands)
7- According the child's abilities you can build up more advanced exercises.