Helen’s left foot slipped off the clutch on impact, twisting her ankle against the car’s floorboard. It felt like a minor sprain at the time, she recalls, but the pain never subsided. Instead it intensified. Eventually, the slightest touch, even the gentle brush of bed linen, shot electric flames up her leg. “I was in so much pain I could not speak, yet inside I was screaming,” wrote the young Englishwoman in an online journal of the mysterious condi-tion that would torment her for the next three years.