I was treating a boy who had a concussion recently. Not only did he have Right cerebellar deficiency, but when I put my finger up to check his convergence with his eyes, he was startled. He continued to jump and be taken aback each time I moved quickly in front of his face. This is a bad sign. It usually means that there's inflammation in the upper cortex, or not enough signals to inhibit a startle response. So, after treating his brain, the startle response was gone.
I asked his mom to add some vibration on the right side of his body for homework until I saw him next. She did this and his symptoms were much improved. However, she also used vibration on his face and she said he started to 'do really poorly'. He got dizzy and nauseated and the rest of his symptoms came back! I knew this would not have created good outcome, because the signals from the face use different pathways. But to actually see it clinically was amazing. He is much better today.