One morning in my fourth year of medical school, a vascular surgeon at the University Hospital in São Paulo, Brazil, invited me to visit the orthopedics inpatient ward. "Today we will talk to a ghost," the doctor said. "Do not get frightened. Try to stay calm. The patient has not accepted what has happened yet, and he is very shaken."
A boy around 12 years old with hazy blue eyes and blond curly hair sat before me. Drops of sweat soaked his face, contorted in an expression of horror. The child's body, which I now watched closely, writhed from pain of uncertain origin. "It really hurts, doctor; it burns. It seems as if something is crushing my leg," he said. I felt a lump in my throat, slowly strangling me. "Where does it hurt?" I asked. He replied: "In my left foot, my calf, the whole leg, everywhere below my knee!"