I think it's the anaesthesia that quiets the nerves. When nerves are QUIET, they can't mis-fire, hence (for a short while), no pain.
We asked Alan's neurologist "how come when he takes his alprazolam before he goes to bed, that all the pain is gone and he drifts off to sleep."
She looked puzzled and this is exactly what she said:
"Well, it might be that it calms his nerves, they all go to sleep, his mind settles down, he doesn't have to concentrate on the pain, and he can let go.....and sleep.
Too bad he can't do this all day long. But hey, he at least gets his 8 or 9 hours in.
P.S. Hi kmeb. sending you a gentle hug.