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How the Discovery of a Brain Imaging Biomarker for Chronic Pain Could Disrupt the Legal System

Advances in neuroimaging could contribute to the objective verification of chronic pain and serve as proof in legal cases

By
Meeri Kim, Contributor
Wed, 11/29/2017

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In a recent case arising under U.S. federal disability law, a municipal worker injured in a car accident while on the job complained of chronic pain several years later. Like many chronic pain patients, she had no visible lesions -- her structural MRI scans had no gross abnormalities -- yet she suffered from severe headaches and back pain. Because of this lack of objective proof, her claim for disability benefits was denied.

Unfortunately, case outcomes like this one remain typical for those suffering from chronic pain. The inability to prove the existence of pain without a visible injury or objective biomarker has led to the dismissal of valid disability claims, as well as the rewarding of fraudulent ones, legal experts say.

In an effort to remedy these issues, some experts have proposed the use of new types of brain imaging evidence as proof of chronic pain -- for instance, a functional MRI (fMRI) scan that shows activation in brain regions associated with pain. A review paper published by the Harvard Review of Psychiatry in November discusses the biology of pain, how Anglo-American law confuses chronic and acute pain, and advances in neuroimaging that could soon contribute to the objective verification of pain.

“I think brain imaging could be evidentiary of chronic pain at the individual level, but we'd have to establish consistent imaging protocols and a better confidence interval on markers of chronic pain,” said Amanda Pustilnik, review author and professor of law at the University of Maryland School of Law in Baltimore. “Then eventually we could say something like, 'We have 80 percent confidence that this person has a chronic pain disorder that is severe.'”

Chronic pain is defined as pain that is present daily for over three months or beyond the expected period of healing. While acute pain serves as an alarm bell for tissue damage, chronic pain has no such adaptive function. It affects up to 35 percent of the population, contributing to a reduced quality of life for the individual and loss of productivity for society.

Despite research studies proving otherwise, the belief persists that chronic pain is purely psychogenic with no biological basis. Even the American Medical Association, in a 2013 practice guide on evaluating legal claimants with chronic pain, says that the condition in most cases is caused by a personality disorder. Patients are also accused of faking pain to play the victim or for financial gain.

“Chronic pain, in order to legally qualify as a disability, has to arise from some other condition capable of causing the pain,” said Pustilnik. “That sounds reasonable, but the problem is that chronic pain disorders can be disorders in themselves.”

Recent research has shown that patients with chronic pain have experienced pathological central nervous system remodeling. For instance, neuroimaging has discovered changes in regional gray and white matter volumes and density, as well as structural and functional connectivity. However, there is no biomarker of pain that currently exists and could be used in a legal setting, she said.

Even without a biomarker, Pustilnik believes that findings from neuroimaging can help update the legal system's definition of chronic pain as distinct from acute pain and a separate condition unto itself. In individual cases, the neuroscientific model of chronic pain could help as framework evidence, or phenomenon-level information that challenges commonly held but erroneous beliefs.

David Seminowicz, who directs the University of Maryland's Pain Imaging Lab in Baltimore, thinks that Pustilnik's paper covers an important topic. His research uses brain imaging to predict with high accuracy whether an individual is experiencing pain and, if so, how intense that pain is. However, he noted that there are still issues with taking his methods to the courtroom.

“In our lab, we test pain responses in hundreds of people and see all sorts of reactions, from extreme sensitivity and fear to the mildly intense pain, to the other end of the spectrum where a person rates the pain 9 out of 10 but doesn’t seem bothered by it at all,” said Seminowicz. “The brain imaging tools we currently have would show that the latter subject has a much higher pain intensity, but it tells us nothing about the underlying experience.”

He believes that new advances in brain imaging technology -- perhaps going beyond fMRI -- will lead to the eventual discovery of a pain biomarker that could be used as proof in legal cases. Because fMRI isn’t very quantitative, he said, other technologies like positron emission tomography or electroencephalography could be better candidates.