Fresh from the clogged tubes of teh intarwubs…
"Evidence from pain synaesthetes would seem to lend some weight to the idea that the brain mirrors the physical aspects of pain, since it would make sense that their physical sensations would arise through some malfunctioning of this mirror system. "It is highly plausible that [sensitivity] for pain is common in all of us, and varies in response to seeing or thinking about another in pain, from tingling through to the actual perception of pain," says Bernadette Fitzgibbon at Monash University in Melbourne, Australia.<br />
There is, however, one key difference between pain synaesthesia and other types of hyper-empathy. Besides having a heightened sensitivity to another's pain, all the documented pain synaesthetes shared one other characteristic – they had all suffered traumatic pain before developing the condition. Many are amputees, and their phantom limb is the site of the pain they feel when faced with another's distress… "