inspired by  a re-reading this report:
Effectiveness of Transcutaneous Electrical Nerve Stimulation for Treatment of Hyperalgesia and Pain
and talking to a former (100% cured,) Backaholic, i was  encouraged to drag out from the bottom of the wardrobe, my old “Bodi-tek” machine.
I  bought  a “Bodi tek”  years  ago  (seriously, 2001, 2002) when I thought it would improve my Martial arts.
In my favour i only used it once. I sat there covered in those patches. Twitching.
However,  there is, at certain levels, a validity to the electro stimulation of muscles and, well, according to the report above, some use in the therapeutic relief of pain.
To be honest,  as I write, I am reminded that , about 2 years ago, when  a sales rep from “firefly” came a calling, I got this machine out again, slapped it on various leg lower leg muscles and it seemed to help my achilles tendonopathy ( along with massage, trigger point therapy and some taping) So, if we, in the future, ask you to lie on the massage couch for a short while, hook you up,  and make you  twitch, you’ll know the reason why.
Interesting to see if we can effect the piriformis  thinking about it.