Let me tell you, you will KNOW when or if you have one! It stinks! You will not be able to breathe, swallow, walk, talk, etc.
I was stupid and too stubborn to go in after my first crisis, and had to have a few more before I finally agreed to go to the hosp - ICU for 8 days!
You will feel weaker than you ever have before. It is a feeling you never want to experience - ever. However, if you do, the docs will prolly give you IV IG or the plasma exchange - it will make all of the difference in the world. Trust me on that!
I was started on Pred while there - as well as IV IG - by the 2nd day I felt so good I cried! I was still very weak, but was able to stand, walk, talk, BREATHE on my own.
I was able to keep my eyes open. It was truly a miracle!
By the 3rd day, I was able to EAT - really EAT for the first time in a month - let me tell you it was fabulous! I gorged!
Hope this helps!

Erin