It's just like, he would like to move his left side of his body, but he's not able to transmit the right input to move his left arm and left leg.
그러니까 아이가 몸의 왼쪽 부분을 움직이고 싶어도 왼팔이나 왼다리를 움직이도록 바른 신호를 전달할 수 없는 거죠.