Portable Finger Hand Held 4D USB Mini Mouse
It is off-table, without limitation by operation space and avoiding harm to wrist and muscle. The two dimensions and buttons are simply controlled by fingers.
This new mouse from Brando might be up your alley. It looks like a lame Sci-Fi gun in a low budget movie, but who knows, it might just help your wrist.
4D page scrolling function can be controlled simply by your thumb.