I know it sounds crazy, this seizures thing. But I wanted to speak out my support for your symptom experience... because POIS sometimes has some crazy symptoms and effects. I used to be afraid to tell people all the weird symptoms that I got.
It is a very very complex illness I think.
But to answer your question:
My seizures-- I had less than 10 in 5 years perhaps...
they were triggered when I had a sudden rush of blood to my head, or something...
they sometimes happened when I did a Big Stretch with my arms, or when I suddenly got up from sitting for a long time.
Seizures are a neurological event, as far as I know. They concern the nerves, which run through the spine, and the base of the brain stem... it's a neurological dysfunction. I also found I was having a lot lot of Back and Neck Pain during that time... and my spine was hurting a lot!