First, you have to show the patient – they often get confused about what you are talking about.
-“I want you to take your heel, okay, and put it on your knee, and then run it down the shin bone. Okay? First lift it in the air and then put it on the knee and then run it down the shin bone. Do that again. Try that again, up in the air first, on the knee directly, then down the shin bone. Now, do the other side. Excellent.”
I’m looking for two things. I’m looking for a little shaking of the hand when it moves, or the foot being unsteady – the so-called ataxia of the limb, and what’s going on there is that the cerebellum controls the agonist and antagonist communication. When you want to contract your biceps, you want that triceps to be relaxing. When you want to contract your triceps, you want your biceps to be relaxing. If the cerebellum is not working, the two of them are not communicating and they are both working, and that’s the problem. So, you get this ataxia on movement. It would not be there, that shakiness, when you are just at rest, so it’s not a "resting tremor," it’s an intention tremor. It’s what we call it.
The other thing we are looking for besides this, the shakiness, is dysmetria, or lack of measurement. Are they actually hitting the target? So, it was important for me to see that the heel hits his knee on target and then move down. A person with true ataxia will have both intention tremor and dysmetria. They’ll not hit their nose and then they’ll not hit the finger, and then they’ll not hit their nose. So, you want to see that he hits the target exactly and that there was smooth movement.