Not sure exactly what happened with Mitch. I think it's more than the incident I had. The one I had was scary enough.
I was at the DMV to get my license updated to 'REALID'. When I went up to the desk, the clerk asked me why I was there, and I froze. I could not remember the term 'REALID'. I just stared at her, dumbstruck, trying desperately to pull the term from my memory. Scary, believe me. Clerk was very kind and eventually I got it, but it took a bit. Sometimes, this getting old sucks.

Count me in the dementia camp, though it's not a perfect fit by any stretch. It's not amnesia, it doesn't last long enough. Acute transient global mental immobilization. I just made that up, mostly. Earlier generations might refer to hardening of the arteries to the brain, now some type of sclerotic illness.

Seizures range from a few seconds to the horrible grand mall we all think of. It is quite possible that he has shown what some call zone outs. He might stop mid sentence and 15 seconds begin to speak exactly where he stopped.

Epilepsy is often triggered by a traumatic brain injury like he recently had.

and during his July incident, staffers had gotten him turned around and he seemed surprised at being in a different position.

That's one reason I was wondering about seizure activity. During TIAs, people are generally aware that something is wrong and they come out of it more slowly.

Absence seizures are weird, a person sitting down will keep his balance, ditto a person standing up. A person at dinner might have a fork halfway to an open mouth and will remain frozen that way. Or stop in mid sentence and either resume it a few seconds later or lose their train of thought completely. It's as though for the duration, they are just not there. Falls happen when someone is getting out of a chair or walking or reaching for something. Please tell me he's not driving any more.

Whatever is going on with him, he needs a neuro workup, not some GP looking at him once it's over and saying he's fine. He's not.

not letting his constituents know the extent of his illness.

and anyone who's watched him freeze up in public know knows.

Absence seizures are generally well controlled with medication. Maybe they haven' t found the right one. Or maybe he hasn't been to see a neurologist, hoping nobody outside his staff notices anything (he hasn't noticed, he's unaware) and he's terrified he'll be forced out before he's ready to die on the job.

I doubt this started as a result of his serious fall. I'm betting that whatever this is caused that fall.