Any sort of sport or activity that would possibly place your hand/or hands in the same position that you have them when riding, could exascerbate the pain you are experiencing. I highly suggest, if you plan on continuing to ride dirtbikes, you refrain from any other sport or activity that does as I mentioned above. At least hold it to a minimum.
Also, have you had your vision checked lately?
Jay knows not of what he speaks. As long as I shave my hands before riding, I have no problems. :scream:
The only time I have a problem with my hands going numb is about 15 minutes into a white knuckle trail ride / enduro. Once I hit the first reset and rest for a few minutes, it goes away for the rest of the day, but pushing too hard, going too fast, and gripping too hard at the beginning of a ride cause my hands to go numb.
Rubber mounted bars, silicone sealant in the ends of the bars, and proper sized grips also help. I used to use the big oversized ProGrips because they were nice and soft, but I had less problems when I went back to normal sized grips. I have bigger than average hands, but the ProGrips were too big.
This was a problem for me as well. What I found to be a huge help was to take the supplement for joints. Rescue 911 is one such supplement but you can find the same thing at any pharmacy or grocery store that carries viatmins. Glucosamine and condroitin are the two desired supplement ingredients. My problem, more than likely, is age related.