I've been battling a wrist injury for about 6 months and have been messing around with my handlebar/grip/lever setup quite a bit to get some relief. Historically I run aluminum bars with little backsweep, but I threw an XC-ish set of carbon bar with a lot of backsweep on one bike, and they seem to help. Not sure if its the backsweep, or the fact that they are carbon. I also found the big Ergons (GP1 I think) seem to help. I have Ergon GA3s on another bike and they don't help at all....too skinny and hard.
The thing that has probably helped me the most is an EVS wrist brace. It's a pretty basic inexpensive brace, but for me it offers good mix of support/flexibility. Looks like the one below. I've even been wearing it when doing yard work and stuff. It minimizes the soreness I can get for days after a ride. There are a few similarly designed braces by other manufacturers out there as well. There's one from Troy Lee that looked a little bit more substantial.
I have also had no choice but to tone back the bunny hops, log/rock overs and general trail debauchery that makes riding fun.....which is a real bummer.
I have a suspected TFCC tear, so your situation may be different, but the brace is pretty inexpensive, so not much of an investment to try.