Just a month after back surgery, Nancy Scatena was once again in excruciating pain. The medications her doctor prescribed barely took the edge off the unrelenting back aches and searing jolts down her left leg. “The pain just kept intensifying,” says the 52-year-old Scottsdale, Ariz., woman who suffers from spinal stenosis, a narrowing of the chanel through which spinal nerves pass. “I was suicidal.