I don't think the underlying cause is the same, but I've developed the inability to write certain letters and numbers, or at least not without a lot of effort. Particularly M, N, S, W and 8. My brain knows how to form the letter, but my fingers won't make the motions. Usually I have to move the pencil back and forth in a line 6 or 7 times before the rest of the letter forms. It's kind of embarrassing when someone is watching my sign my name since it starts with an M. I have no idea where this came from, but it hasn't always been the case.