What the researchers found was that those with depression showed a higher level of activity in the areas of their brain that processed emotions. Moreover, the regions of the brain that are normally involved in mitigating pain were less active in the depressed subjects -- a hint that chronic pain may have a propensity to feedback on itself.
Toussaint says the depression that accompanied her chronic pain was nearly too much for her to bear.
"I suffered very, very extreme depression," she says. "All of us with pain do. We're being tortured 24/7, we're not believed, and our lives are upside-down.
"I had a plan of suicide -- not because of the physical pain but because everyone I knew had abandoned me."
Fortunately, pain experts say, the majority of those battling mysterious chronic pain can find answers if they search long enough.
"Most pain does have a label," Cope says. "If you can find some general idea of what's causing your pain, you can tailor treatment toward that."
"A lot of people don't realize that there are treatments available," Christo says. "We do have some pretty reasonable treatments for people that can help control the pain and increase quality of life."
As for the best way to access these resources, Christo says pain sufferers can start with a simple Internet search, using their symptoms as search terms.
"What will usually come up is a description of the condition, and sometimes a directory of self-help groups," he says, adding that some support Web sites even have suggestions for doctor referrals.
For those who have found themselves being pinballed from one doctor to the next, finding a multidisciplinary pain management center may be the best step. Here, patients can afford themselves an entire spectrum of care services -- from pain physicians and physical therapists, to psychiatrists trained in helping those with chronic pain come to deal with their conditions.
"Medication, injections, physical therapy and pain psychology all can come together to significantly improve quality of life," Christo says.
For Toussaint, the medicine that worked best was the anti-seizure drug Neurontin. Today, this medication, combined with a physical therapy regimen that incorporates Eastern and Western healing techniques, allows her to control the pain brought about by her condition.
As is the case with some who face chronic pain, Toussaint may live with her condition for the rest of her life. But she says that those who face a similar struggle must take heart that an answer exists for their mysterious pain.
"Know that you're not alone," she says. "Know that you're pain is real. And know that you deserve the dignity of proper diagnosis and treatment."
To visit the For Grace website, click here.
To visit the website of the American Academy of Pain Medicine, click here.