I have a serious right-hand issue too. It took me a little while, but I figured out it is a repetitive stress issue caused by too much mouse usage on my computer. I've been using a stiffish wrist/hand support and pulled it over my knuckles to immobilise my fingers to a certain degree. It's working so far and giving me back some control of my fingers, two of which became uncontrollable and were quite painful. Your splints sound as if they do a similar function. I'm just trying to do a self-fix to save money. Cheers.