The electrodes stimulated the spinal cords of the patients while they engaged in specific motor tasks involving their paralyzed limbs. Before the patients were injured and their spinal cords were damaged, their brains would have sent those key electrical signals to their legs.

The new study upends the assumption that two years post-accident is a point of no return for people paralyzed due to a spinal cord injury. In the first months after a paralysis-inducing accident, patients might regain some function of their legs and lower torso with hard physical rehabilitation and the spontaneous regeneration of some nerves. But more than two years after these patients have been injured, those treating them have long thought there was little to be done.

The therapy reported Tuesday in the journal Brain proved promising as early as its first week of testing on four paraplegic subjects, each of whom was recruited to the study more than two years after his accident.