Panic attacks can be triggered by flashbacks, emotional flashbacks, or even just plain old emotions. Once you have ptsd, your system is primed to flick into fight/flight way too easily. That’s part of the core pathology of ptsd - the over-sensitive fight/flight response.
So, it could be that an underlying emotion (which you may have numbed yourself out to) is driving your nervous system over that panic threshold that is waaaay too easy to go into with ptsd.
“Panic attacks” are usually something people talk about in relation to anxiety disorders. With ptsd, it’s common to hear people talk about fight/flight, but essentially the same thing is happening. Just different terminology.
Darting eyes and stuff? Sounds a lot like your nervous system heading into that fight/flight response.
You mentioned that when it ramps up, you just shut down completely? “Fight/flight” actually also includes “freeze”, “fawn” and “flop”.
Fawn is a complex one. Flop? Is when your brain has decided “Lion is about to eat me, I’m done”. Your system has shot past fight/flight (when your eyes are darting) and is now reducing your level of awareness, your arms and legs go floppy, and brain is flooding your body with hormones and chemicals that will make you numb.
Between fight/flight (aka panic attack) and flop? Is freeze. When your system is starting to shut down because the darting eyes has gone on too long, your system freezes.
Emotional flashbacks and emotional states aren’t irrelevant just because someone has called something a panic attack. Plenty of times I’ve had flashbacks that have caused me a panic attack, sometimes going right through to flop when my body is just a jelly-like unresponsive blob. Emotions and flashbacks can do that.
What’s going on for you? Could be all of the things you mentioned, with the outcome you’re describing being a panic attack. What might be more helpful to you is switching the language: my emotions/flashbacks have caused my system to go into fight/flight/freeze/flop.
Understanding the process (this might feel instantaneous, but there are still quick steps involved) might help you start to recognise those moments when this is starting to happen.
Building the skill of recognising what’s happening, as it’s happening? You’re halfway to solving this problem. All that’s left? Is figuring out the skills to apply to stop it happening. Like, completely.
Which would be totally awesome!