According to the 2011 Institute of Medicine's Relieving Pain in America Consensus Report, 100 million people in the U.S. suffer from chronic pain. That is nearly one out of every three people. Yet no two individuals experience pain in quite the same way. The highly subjective and personalized nature of pain make it a complex problem to diagnose and treat.
Understanding how to predict, prevent and alleviate pain remains the mission of the Stanford Division of Pain Medicine, according to Division Chief Sean Mackey, MD, PhD. In the last decade, he has seen dramatic changes in the way pain is understood. Rather than viewing pain as simply a symptom of trauma, infection, inflammation or surgery, pain specialists like Mackey now see it as a discrete disease entity — one that fundamentally alters the entire nervous system. Advanced neuroimaging tools have allowed them to peer inside the brain, unlocking mysteries of where pain is perceived and processed, how it affects the brain and how it can act to change thoughts and emotions.
"For the first time, we have the tools to effectively explore the impact of pain on the brain," says Mackey. "And we can use this information to create the comprehensive interdisciplinary treatment needed to prevent or reverse these changes."
Stanford tests objective pain-o-meter
Although pain is a major symptom and indicator of many illnesses, physicians must currently rely on their patients' subjective self-reporting to measure pain. "One of the key things we have all been searching for is an objective way to determine whether a person is in pain or not," says Mackey. "There are huge individual differences in how people experience pain, and it’s not directly correlated to the extent of the injury."
In a study published last year, Mackey tested a method of analyzing brain structure using advanced computer algorithms that accurately predicted whether a patient had lower back pain 76 percent of the time. Mackey's team used a machine-learning approach to perform the study. Using these pattern classifiers, the same type of algorithms used by Google in its search engine, Stanford researchers were able to find patterns of brain activity and brain structure that correlate and predict the experience of pain.
"This method may one day augment self-reporting as the primary way of determining whether a patient is in chronic pain," says Mackey, professor of anesthesiology, perioperative and pain medicine, and neurosciences and neurology (by courtesy).
Genetics play a role in pain treatment
And just as individuals experience pain differently, how patients respond to pain treatment is also highly variable and genetically predestined, according to a separate study by Martin Angst, MD, professor of anesthesia. Although opiates remain the mainstay medication for easing pain, they don’t work well for everyone because of side effects. The Angst study showed that genetics play a significant role in determining which patients will suffer the most from disturbing side effects of opiates such as nausea, slowed breathing and dislike for a drug.