Is it Nerve Damage?

So this isn't an emergency or anything but I am curious. Vincent is just under two years old. I found him in the snow in the Adirondacks as a kitten of about 4 months old. He had frostbite and the tip of his right ear died off a long time ago... (picture for reference) 


Sometimes when Vincent is getting pets and you accidentally graze his ears he will have a massive involuntary twitch with his legs. It definitely doesn't seem to hurt him, he usually acts as if it doesn't happen. This same strange convulsion happens when touches ice on his face or paws. (It being summer here in VA, I let him play with ice cubes since he begs for them when he hears the ice machine.)

Another thing he does that I don't understand is when he's relaxed (usually on his back or side) he will have what looks like a very slow and steady convulsions/spasms in a leg (seen it happen in every leg but only one leg at a time) and it is NOT like the REM twitching you see animals do in their sleep. It is a very steady, even, and slow 'bouncing' that he doesn't seem to notice. I try to get it on film but it doesn't usually last more than 30 seconds. When he does it, it looks very surreal, I've never seen a cat's legs move so oddly. 

I guess anything is possible?   Have you ever asked your Vet? 

All I can tell you is we had a dog who had Frostbite on his paws, and when they bothered him,he would chew on them.  We supposed then got numb, or at least that's what our Dad told us...not sure if that's what the Vet told him or what.  'Course, that was at least 50 or more years ago, so probably everyone was guessing   (just like I am with I said "I guess anything is possible" )