Chronic pain affects more than 100 million Americans, according to the American Academy of Pain Medicine. That’s more than diabetes, coronary heart disease, stroke, and cancer combined. It also doubles the risk of suicide. Yet, unlike for most of these diseases, there is no objective diagnostic tool to measure how much pain a patient is feeling.
Instead, patients and doctors have to rely on highly variable self-reports that rate feelings of pain on a scale from 0 to 10. Since each person experiences (and reports) pain differently, it’s often hard for doctors to tell who is really suffering and who needs treatment the most.
“The biggest challenge is that there are no objective tests,” said Dr. David Borsook, co-director of the Center for Pain and the Brain, a professor at the Harvard Medical School, and director of the P.A.I.N. Group at Boston Children’s Hospital, in an interview with Healthline. “That means we’re at the whims of listening to a patient and the diagnostic skill sets of the physician, or lack thereof. It’s very hard for patients to express what they’re feeling and suffering in the short time they see physicians. For physicians, they’re under pressure to see patients quite quickly, and pain is a complicated process.”
This created problems for Leslie, 54, of Fairless Hills, Pennsylvania. After twenty years of fighting recurring oral cancer, she developed a different relationship with pain than most people. So when she tore her rotator cuff, the pain didn’t seem so severe by comparison.
“They kept asking me on a scale of 1 to 10 — and I’m so accustomed to 10 being tongue cancer pain that nothing compares to that — and I kept giving him a 4 or 5,” Leslie told Healthline.
“After almost a year of it, I said ‘I know something’s wrong with my shoulder. It’s hurting, I can’t function,’” she said. So she told her doctors that her pain was a 9, which finally prompted them to order an MRI. The scan confirmed what Leslie already knew: her shoulder was badly injured and required surgery.
On the other side of the equation, a patient might exaggerate symptoms in order to get access to prescription pain medications. The Centers for Disease Control and Prevention (CDC) reports that more than 12 million Americans used prescription opioids for nonmedical purposes in 2010. Such drugs were involved in 14,800 overdose deaths in 2008.
Borsook says that deciding whether to use opioid medication is a tough, and hotly contested, decision. “There’s good data to show that many patients who are prescribed opioids go on to have an addiction problem,” he explained. “The difficulty is that, on the flip side, there are many patients who are helped tremendously with opioids, and how do we differentiate that you’re a responder with low risk for addiction, or that [you’re] a nonresponder or have a high risk of addiction?”
When it comes to pain management, there aren’t a lot of other pharmacological options, Borsook added. This means scientists badly need to find a biomarker — an accurate, measurable sign in the body that can tell doctors who is experiencing pain, how much of it they’re feeling, and which treatments will work best for them.
The Business of Measuring Pain
A new wave of research over the past 15 years has unlocked a number of potential biomarkers. The most notable new technique is functional magnetic resonance imaging (fMRI). Doctors scan the brain to measure differences in blood flow to tell which brain regions are active at a particular time. Some scientists, like Tor Wager at the University of Colorado, Boulder, and Vania Apkarian at Northwestern University, have begun to map out how acute and chronic pain appear in the brain using fMRI scans.
The two types of pain don’t look the same on a scan. While both involve the insula, the brain’s primary pain detector, chronic pain also involves brain regions associated with emotional regulation.
“Pain is a complex, multidimensional experience that many studies have shown necessitates a number of brain regions,” said Andy Segerdahl, a researcher at the University of Oxford, in an interview with Healthline. “The perception and experience of pain most likely emerges from synchronized communication between many brain regions; it does not arise from a single part of the brain alone.”
Chronic pain is especially tricky because it’s an intricate condition that may have multiple origins that require different treatment strategies.
“I think the real problem in chronic pain is that it’s unlikely one treatment will work,” said Borsook. “When you take [one treatment], it may only affect one of those circuits. It may not be enough that, in affecting one circuit, it can have a domino effect of correcting the others.”
One company, Millennium Magnetic Technologies (MMT), has already taken this fMRI research and used it to start helping patients. Using brain scans of patients who report chronic pain, MMT creates a series of images to illustrate the patient’s pain for use in insurance and disability claims.
Although a few court cases in New York and Arizona have accepted such scans as evidence, they only represent the tip of the iceberg. More than 95 percent of personal injury cases are settled before they go to court, explained Carlton Chen, MMT’s general counsel.
“What we’re finding is that when the defendants see the documentation and they’re reassured that there is indeed objective evidence of pain and they’re able to quantify it, they’re more amenable to coming to a settlement,” explained Dr. Steven Levy, CEO of MMT. “It removes a barrier that is otherwise there.”
Such technology would be a game-changer for people like Emily, 28, of Berlin, Connecticut. Emily was born with a rare condition called Klippel-Feil Syndrome, which caused seven vertebrae in her neck to fuse and caused spinal cord abnormalities. Although symptomless for most of her life, at age 24 she spontaneously developed muscle and joint pain that spread throughout the left side of her body.
Because of her cheerful and upbeat demeanor, she had a hard time finding doctors who would take her “invisible” pain seriously. “Just because I’m not coming in and crying hysterically — that’s part of having chronic pain — you can’t cry every day, because then you’d just be a disaster,” she told Healthline. “Even though I’m not showing that I’m in pain, doesn’t mean that I’m not in pain.”
It took Emily more than two years to fight her way through the courts and get approved for disability payments. She believes MMT’s work could help other people in her position.
“I think it would be tremendously helpful for doctors, and in court cases having patients be better believed and not having to fight so hard for the benefits they deserve,” she said.
Are fMRIs Ready for Prime Time?
The question is, are these imaging techniques rigorous enough to be used as evidence? Current tests for chronic pain have come in at about 92 percent accuracy. That means as many as 8 percent of patients with chronic pain can still fall through the cracks. And there are lingering questions about what certain fMRI readings actually mean.
“The issue of recognizing a neurological signature of clinical, and especially chronic, pain is much more demanding and yet unresolved,” said Carlo Porro, a professor of human physiology at the University of Modena and Reggio Emilia in Italy, in an interview with Healthline. “fMRI patterns associated to pain might differ according to the type of pain and clinical cause.”
Borsook doesn’t think the science has advanced far enough to use fMRI as a biomarker for chronic pain. “There’s no question that the biomarker is not being validated,” he said. “It’s not used routinely in any medical center; it’s not used routinely in drug development. If there was such a thing out there, it would be like a diagnosis for diabetes — every hospital uses it. I know the field does not have that.”
Dr. Sean Mackey, who submitted written arguments as an expert witness in a court case for a chronic pain disability claim, agrees. “These [fMRI study results] are under carefully controlled laboratory conditions,” said Mackey, division chief of Pain Medicine at Stanford University and the immediate past president of the American Academy of Pain Medicine, in an interview with Healthline. “They don’t yet generalize to the broad population. It’s not ready to be used as a clinical diagnostic test and certainly not in a medical or legal environment.”
There simply haven’t been enough tests, he explained. “There’s a large number of challenges that we have not yet addressed. [We] haven’t yet looked at whether or not somebody can fake this. Secondly, we don’t know whether the patterns of brain activity being represented in a particular situation — does it represent pain? Does it represent some generalized emotional distress? Anxiety, fear, depression?”
Another problem Mackey explained is that general neuroscience findings can’t be applied to individuals, any more than knowing the average height of an American woman will tell you the height of any specific woman.
Tor Wager is also reluctant to see his work used as evidence to support MMT’s claims. “I do not believe the MMT analyses have been validated in groups of patients or published, and doing so is essential for this particular use of brain images,” he told Healthline.
Levy maintains that MMT is not intending to provide research data, but instead to get help to pain patients who need it now. He hopes that as the research does progress, it will continue to lend validity to his work.
“We expect that it’s just a matter of time before other courts and other jurisdictions accept this testimony by neuroscientists. As this technology becomes more available, this will find its way into the courts and become more and more accepted.”