I actually have had that happen to me three times but it started before Mirena when I was pregnant with my last baby. I was at work and first my right hand finger tips went numb then it spread up my right arm and to my face. I couldn't talk and I wanted to call my husband but I couldn't figure out how to work the phone. Lasted a few minutes and afterwards it was followed by one of the worst migraines ever. I went to the ER and was tested but they couldn't find anything. I followed up with more testing in the Neurology department and what they determinied was that it was complicated migraines, not a stroke. I'm not sayign we had the same thing but I know with all that Mirena puts us through we can be quick to blame health problems on the IUD but sometimes it's unrelated. I really want to blame my new Sciataca on Mirena but frankly I think I'm just getting old. lol
I hope it's just migraines for you and nothing more serious. Knock on wood I haven't had one in a really long time but I also cut out caffeine and junk foods. I think that helped me a lot.