I find the same thing sometimes. Sometimes I can identify a thought or feeling before I panic, but sometimes they come out of the blue, when I am not expecting them. But if I get up in front of an audience for whatever the reason; I get very nervous. I think this indicates a fear-provoking thought of some kind. Medications help; but I think most people get nervous in front of an audience, even if they don't have panic attacks. In a classroom setting, depending on who the students or listeners are, it is also frightening. I believe the feeling for me is what if I turn red; which will be a signal to everyone that I am nervous. Well; I suppose that is similar to your feeling of what if they hear my voice shaking, or see my hands shaking, etc. That could be your fear-provoking thought...that you will look foolish somehow. But as one of the support group has told me..I should think about how many out of 100 people would notice? And out of 100 people how many would care that much about your shaking? Well, I thought perhaps depending on the situation it would differ on any given occassion. What is the worst that could come of it? I thought, perhaps a lowering of self esteem, in a public speaking situation for myself. You would have to think about it for yourself. It is covered in the Panic Program, I believe in the third section under Challenging Anxious Thoughts. I believe that unless you are just totally stressed out about everything, panic is usually caused by some kind of a thought, even if it is a subconscious one. If there is no fear provoking thought beforehand, then perhaps it is an autonomic nervous system reaction just by so many things stressing you out you cannot decide on any one thing. Sometimes it is just difficult to figure it out.