I don't know anything about the two syndromes you mentioned but I do also get this symptom. It affects my feet more than my hands but both are involved. On my feet, it's usually my second and/or third toes that go numb, with my fingers it jumps around more but usually is my pinky. I don't really have any advice or info about it, just wanted to let you know you're not alone in it.

--Annie

The symptoms are ...
numb little finger and finger next to it.
Also it can effect your palm..Half of my palm is numb.

I am now having problems with trigger thumb.

One way to realive it is to make sure you are not bending your elbow and putting pressure on it while talking on the phone or the computer.

At night you can use a towle and wrap it around your elbow to keep it straight.
When it is straight it takes the pressure off the nerve.

I am not a doc...just telling you what my doc told me.