Anyone ever had any problem related to wrist lesions caused by keyboard or mouse? Tendinitis? Tenosynovitis?
How long it lasted? How did it go away?
Not using the mouse seems to be the key for me. I use it more than I like to admit, but mainly only to move and focus windows, to copy/paste text, and, regrettably, when surfing (Firefox is somewhat frustrating to drive by keyboard, and most web sites ruin what little usability there is in the browser itself). Thunderbird is even worse, but I'm trying to switch back to Gnus now for that reason. Stuff that doesn't scroll from the keyboard, or has unexpected key bindings for scrolling, tends to drive me nuts because for me, scrolling is probably the worst mousetrap, as it were.
I had a minor strain of some sort maybe ten years ago, but it went away by itself, partly perhaps because I moved the mouse to the other side of the keyboard while it lasted (not more than a week, and it wasn't very severe, but moving the mouse back was a relief).
The general advice is to have a good keyboard and mouse which suit your personal use, and ditto for table and chair. Still, shift positions while working.
Another thing I'd recommend is making sure that your entire hand is supported (from the elbow down)... That helps a lot.
I didn't have anything as serious as tendonitis, but I did get shooting pains up my arms. Two big wins for me were:
1) make sure your posture is correct. Install a program like workrave (Workrave) and when it reminds you to take micro-breaks, remember to sit properly and take a drink of water too.
2) give the dvorak simplified keyboard a go. it's easy to learn and a *lot* more comfortable than QWERTY, plus all systems have it pre-installed because it's a standard. A good place to look for info was dvzine.org which is now extinct, but you can find it in the wayback machine at archive.org. A good online tutor is A Basic Course in Dvorak (google "abcd dvorak")
I won't vouch for Dvorak speed claims, but it has definately solved the problem of pains in my arms. Plus because I'm actually a touch-typist now (never learned QWERTY after 15 years!) I think that has helped at least as much as the different layout, so if you're reluctant to try it, at least learn to type properly on "normal" keyboards.