Seriously, That does happen to me. I usually am able to sit down , before I fall down. My mind slowly shuts down. Too much data- can not compute, overloading occurring. I stay seated for several minutes, then I'm able to resume my activities. My GalPal used to take these events personally, but now she understands that she needs to help me by taking control, stop asking questions, Etc.
My lesion is at C5-6 which is pretty high up the cord and may influence the Pons. I'd recommend googling "Pons". It's a pretty interesting part of our brains. F
