I've forgotten the exact acronym that TENS stands for(someting like Topical Electronic Nerve Stimulator?), but I've got a TENS unit and it works!.
It's basically a small battery powered unit used for pain management. You attach electrodes around the affected area - the lower back in my case - and you can "jam" the appropriate nerves responsible for pain conduction. This is done by tuning the variable frequency, variable amplitude pulse controls to find a setting that suits your particular condition.