Machines like TENS are very simple to operate and can really help some types of pain, but seeing Alan can't feel anything in his feet, Dakota brings up a good point, if it got accidentally turned up to the highest setting and left running for who knows how long and Alan couldn't feel anything, this would be a real worry.

I have used my machine up on very high settings when my hip was giving me grief, i never got any burns or anything but there is big differance, i could feel it and i knew when to turn it down, i think playing safe as you are is wise.