Is brain Imaging for pain measurement reliable enough for the courtroom?

Papers-I-Read Neuroscience Ethics Nature

30 Mar 2021

Link to Paper

In recent years, several neuroimaging-based companies claim to detect pain signals using fMRI (functional magnetic resonance imaging). Such scans for measuring pain have been used as evidence in court trials in cases involving claims of unresolved pain. Although there is a real chance at helping someone in pain by providing “proof of pain” through brain imaging techniques, it is also important to examine if such methods are actually even correct and ethical or if they can be fooled, an allure to wrongly acquiring money.

Pain is a very subjective experience. To objectively quantify it, we look at the source of the experience - the brain. Several researchers over the years have tried to understand the nature of pain using fMRI on the ground that pain shares common elements. A study at the University of Colorado investigated pain’s signature by placing people in an fMRI scanner as they touch a hot plate. Note that acute pain is being measured here. However, most court cases question the truthfulness of chronic pain. A study at the Northwestern University in Chicago scanned people with back injuries over the course of one or more years. A shift of the pain signature from the insula (associated with acute pain) to the amygdala (associated with emotion) and medial prefrontal cortex (associated with cognitive behavior) was observed; “pain is becoming more internalized”. This suggests an emotional connection to chronic pain, which may also reinforce each other.

It is relevant for science to research the nature of pain and attempt to quantify it objectively. But are the current methods accurate enough to be used in court? Given how fMRI scans have been regarded as evidence for pain in court, it is critical to scrutinize the feasibility of pain imaging both from a technical and ethical point of view and discuss its limitations.

Technical Feasibility

Given the current state of the art, it is fair to say that the current advancement in pain measurement by brain imaging is not reliable. Maybe it will be sometime in the future, but not now. Pain cannot be reliably localized to a particular brain region. Hence finding biomarkers might be advantageous. Even if the exact biomarkers are known, the challenge exists in quantifying the degree of pain at a personal level and associating it with brain regions and brain activity.

Something as subjective as pain is difficult to detect using fMRI. Increased brain activity might suggest more pain, but does not necessarily quantify pain well enough to take a legal decision. Someone’s pain tolerance might be someone else’s nightmare. The subjective character of pain makes interpersonal comparisons hard. It is important to not undervalue someone’s pain and make a decision based on it by objectively measuring pain from different subjects on a common scale. Further, all this study is based on inverse inference, which might not even be true given the abstract nature of pain. Signatures detected in pain could be seen in subjects, not in pain.

fMRI mainly measures blood flow and has a poor temporal resolution which is an issue in measuring acute pain. EEG can be useful to detect such changes. During studies, for eg. using the hot plate, it can be difficult to decouple actual pain from the thought of pain. EEG and MEG with higher temporal resolution could help deal with this by separating the pain response from anticipation. But this is more useful for acute pain. Once we know the biomarkers, using multimodal imaging methods could be more comprehensive, if the biomarker shows up in all methods. For chronic pain, I think the focus should be placed on detecting maladaptive changes and functional reorganization in the brain images as an indication of pain.

It is crucial to think about how one might fool the imaging by thinking of pain. People could also physically/mentally hurt themselves before a scan to get a positive result. Therefore, a better understanding of pain signatures and their causes is of need. However, the potential for easily deceiving the method should not prevent us from studying this further.

Ethical Analysis

Let us assume that we have a perfect way of detecting and quantifying pain using fMRI. Even then it is questionable to measure how much pain a person is in, let alone use it is as evidence in court. Can courts even accept such brain imaging results as proof of pain? If yes, how much weightage should be given to such evidence, given how there is a clear “neuro” bias found in public.

To “measure” chronic pain, a woman with back pain was imaged before and after walking. This makes us question if it is even okay to force people in chronic pain to perform tasks to induce more pain, such that a biomarker is more strongly measurable? Further, tests like an fMRI scan are not accessible and also really expensive and can even cost up to $4500. The cost can also hinder people who may genuinely need such a piece of evidence in court from having one.

Accepting such brain images in court will also increase the burden of proving one’s pain. It can also lead to forcing people to undertake these tests becoming commonplace for use in health insurance claims, medicine prescription, etc. It can cause trust issues and make us question people when they say they are in pain if they don’t have a positive pain test.

The incentive structure of this method can encourage people to cheat for money, leaves, insurance claims. It can also force people who actually are in pain, to wait to take such a test when they are hurting more. Additionally, making interpersonal comparisons of pain just for treatment, compensation, etc is unjust and gives the idea that being more in pain is advantageous.

Having proper pain measurement methods does not make the underlying social issue that makes such a test relevant in court in the first place. The incentive for most of these cases in court is poor health insurance systems. A well-functioning health care system may reduce the need for pain detection, at least in legal cases.

All this said pain research is important both for science and society. Such a method can help to secure an out-of-court settlement, saving a lot of time and money. It will also help combat stigma against people in chronic pain by providing a way of it. The communication of scientific breakthroughs influences the way the public perceives and utilizes such technologies as pain measurement. Therefore it is important to both introduce and use such pain measurement techniques judiciously.

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