For me, as funny as it seems its when I have right eye, instead of left eye ptosis. not a big deal in itself, as you say, but 9/10 if I don't stop I will crash within a short while. Problem is that I don't always have this sign, and have learned to recognize others as well.

As to crisis, I was really lucky that my respiratory problems were always addressed by excellent pulmonologists, who used non-invasive respiratory support very early on, as well as IV neostigmine, PLEX etc. In many (probably not all) cases you can prevent the need for intubation by using NIV instead.
Also, once you get adjusted to it, you can use it on your own at home (as long as you know how to, what to monitor etc.) and don't even have to go to the hospital.

Tysondouglass - It's good that you got that much info, but, as you said, more of what you already knew. That's good confirmation though.
My GI doc actually sent me for a manometry where they insert a sensor in the nose and down into the stomach then withdraw it slowly while having you swallow sips of warm salt water. It was so much fun.... Anyway, I'm sure it would have shown the weakness of my swallow but, unfortunately, the data was lost and there was no way for my doc to retrieve it. He wanted to repeat the test but I respectfully declined. Definitely not something I would ever want to do twice. The nurse who performed the test kept telling me to "swallow better, swallow harder" so I know she was seeing something. Too bad the doctor wasn't there for the test.

: you are absolutely right, you could use the voice as an indicator of weakness. I was getting very hoarse, took a nap, when I got up I talked fine. Someone tell my husband he can't shut me up for long~lol