Neuroplasticity and the "body map"
After amputation, the brain retains a "map" of the lost limb. The nervous system continues to receive and generate signals that the brain interprets as pain, spasm, "twisting" or "squeezing" of the phantom hand or leg. This is not an "imaginary" pain but a real state of the nervous system.
The goal of treatment is to gently retune this map, giving the brain new adequate movement and sensory signals so that phantom pain decreases and stops interfering with life.