All nerves are comprised of neurons who past the drive either toward or far from the cerebrum by being turning them on or off. The principal neuron turns on, passes the information to the following neuron without any end in sight it goes. All of these neurons have a period when they can't pass motivations as they are energizing. The TENS unit sends electrical upgrade which shields the neurons in your spine from reviving henceforth making them unfit to keep passing the torment motivations upward. On the off chance that you kill the TENS unit, the torment returns so as much as it alleviates torment, it doesn't 'fix' it.
** I may take note of this is an extremely basic outline of how it functions and it would take a school level course to try and cover the fundamental ideas.