First, I am not a medical professional. I am simply a person who suffered from repetitive stress injury (RSI). I had tried many things to alleviate the pain I felt shooting up my forearm and up into my shoulder blades.
When I purchased this I looked at other computer mice that would possibly change how I would place my hand and arms but none worked like the Penclic Ambidextrous Mouse. In as little as a month I noted the change and the pain began to back off.
Of course, you should consult with a physician to ensure you are not having other issues but if you use a pc and want to avoid RSI this may be something to add to your workspace. I highly recommend the Penclic D2 or D3 Ambidextrous mouse. The D2 is pictured here and is wired. I prefer wired over wirelss but both are great.