Medicine: An Hour When Life Stood Still

For seven months the blond, chubby-cheeked twins ate, slept, cried, had their diapers changed, just like babies everywhere. But they gazed at the world around them from an awkward and virtually immobilizing position. The two were joined at the back of the head, with their faces turned Janus-like in opposite directions. Sitting up or crawling was impossible. By the time they were brought to Johns Hopkins Children's Center in August, they weighed a total of 30 lbs. -- too heavy and clumsy a bundle for their mother to carry easily.

Last week, for the first time in their brief lives, Patrick...