Many years ago I briefly used a tens unit for back pain.. mine had like battery pack with a little wire that led to a patch or two. You stick the patch on the problem area and then you turn the patch on to different levels and it sort of vibrates and pulses and makes the muscle under the patch twitch and tingle and this can give a sense of relief and this might help relax the muscle kind of through electric jolts which is like deep massage in a sense.
...Anyway that was what I remember experiencing. Like I said that was many years ago and maybe the tens unit has changed a little but regardless it sounds like this tool can help ease some suffering! That is Wonderful news...
..also what's super nice about it is the tens unit is a non-invasive measure to use in the sense it's not drugs or internal medicine but rather an electrical tool one can turn off and on and just use it for a certain amount of time.
(For example, if one used a tens unit while doing dishes or after a little physical therapy or exercise that would be a a lot better than tearing your insides up from popping too much Tylenol or getting hooked on pain pills or something that the body tends to build a tolerance to anyway.. Although I am not a medical expert and can't give qualified medical advice, I would venture to guess one is much better off messing with a tens unit!)