One of my mares tosses her head like that (if that's what you meant by twitching) when I'm riding her. I think her problem is her hair tickling her ears as we go forward. When I rubber-band her forelock down and stick it under her browband, she pretty much quits.
I even tried that.
He's head tossing was a violent jerk. either up, or down, or to the side. I came home sometimes with green splotches on my pant leg from him bumping his mouth into my leg.
When I first started holding his head down as the trainer told me, (this was after the sulling up was cured), it seemed to start helping one day. Another girl was with me. I was really concentrating on him, we weren't talking much. But he went for about 10 minutes with out doing it, and she said, maybe he's got the idea. I told her, maybe, but he may try something else now. Guess what:), he suddenly slammed on the brakes and went flying backwards. We crashed into her.
I started spurring him really hard. Hard enought to make him fart:). He pulled that stunt about 3 times, then went back to twitching. It seemed the one thing he figured he could do, and I could come back with anything to make him stop. You can only hold a twitching horse head down for so long before your arms give out.
Becky
Towards the end of my time with him, I always rode with a tie down, because he did bash me in the face a few times. Once I put the tie down on and he hit it a few times, he never came up again, then it was always down, or to the side. That tells me he was a very smart horse, and just rebelling in a way he could.
I thought about putting his neck in a steel brace:)
Becky