What causes phantom limb sensations and how are they treated?

The answer

Phantom limb sensations affect 80-100% of amputees, with 50-80% experiencing phantom pain. Neuroscientist V.S. Ramachandran pioneered the explanation in the 1990s: the brain's somatosensory cortex retains the neural map of the missing limb, and adjacent cortical areas 'invade' the vacated territory. Touching an amputee's face can produce sensations in the phantom hand because face and hand regions are adjacent in the cortical homunculus. Ramachandran's mirror box therapy - using a mirror to create a visual illusion of the missing limb moving - reduces phantom pain in 60% of patients by providing visual feedback that 'unparalyzes' the phantom. Modern treatments include virtual reality systems and targeted muscle reinnervation surgery, which reassigns severed nerves to remaining muscles.