Ketamine is a legal anesthetic often used by doctors, but in low doses. A high-dosage ketamine coma, which Sutton experienced, has yet to receive a thumbs-up from the FDA.

Dr. Kirkpatrick said he tried to get the coma approved in the United States, but gave up after growing frustrated that the agency wanted more trials and information on the procedure. So he sought help from doctors in other countries to treat some of his patients who suffered from RSD. The treatment is also offered in Germany.

Kirkpatrick acknowledges that patients who undergo the ketamine coma may not wake up again. Some wonder if that's a risk worth taking.

"That's pretty risky, to put somebody to sleep for five days and suppress their reflexes," said Dr. Elliott Krane, a professor of anesthesiology and pediatrics at Stanford University's School of Medicine. "In the United States, that would require an intensive care unit."

Krane said that while a ketamine coma could work for some patients, getting FDA approval in the United States would be difficult.

"Anybody could do it (a ketamine coma) in the United States, if they wanted to," Krane said. "They could do it in their garage, I guess, but it wouldn't be a smart thing to do.

You would never get an American insurance company to pay for it because it's such a wacky idea.

"It's one of those things you can get away with 90 times. But on the 100th time, you're going to kill somebody."