A study by researchers at McGill University and researchers in Italy suggests that blocking inflammation after injury may make the pain chronic, a finding that challenges the standard approach to treating pain.
Chronic pain – especially in the lower back – is a common disease, but scientists do not know why some back injuries resolve on their own, while others cause suffering for years.
In this study, researchers found that neutrophils, a type of white blood cell that helps the body fight infection and dominate the early stages of inflammation, play a key role in resolving pain.
Jeffrey Mogil, a research researcher and professor of psychology at McGill University, says standard medical practice for treating short-term pain after an injury may be the opposite of what we need to do.
“We think that chronic pain develops due to inflammation, so we think that inflammation is bad and we need to stop it. But what this study suggests is that yes, but at the cost of increasing your chances of developing chronic pain, “Mogil said.
Although the findings have not yet been tested on people in a clinical trial, several non-study pain experts say it offers a new way to look at how the body treats.
Blood cell and mouse testing
The study, which was published in Science Translational Medicine last Wednesday was conducted by nearly two dozen researchers who studied pain in three phases using human blood cells and experiments with mice
They examined the blood cells of 98 patients with acute low back pain and looked for markers of inflammation. Three months later, they did the same test – comparing those who still have constant pain and those who do not.
Patients whose pain disappeared showed more inflammation at the first visit, which appeared to be caused by neutrophils, a type of white blood cell. On the second visit, their blood cells showed a change in gene expression in several thousand genes.
Jeffrey Mogil, a neurologist and professor of psychology at McGill University, says the findings call into question what has become standard treatment for short-term pain. (McGill University)
“Absolutely nothing happened in the blood of people who did not get rid of their pain,” said Dr. Luda Diatchenko, another research researcher and professor of dentistry and medicine at McGill University. Both groups of patients used anti-inflammatory drugs, she said.
The researchers tested on mice and confirmed that blocking the inflammation with medication relieved them of pain for a short time, judging by their sensitivity to touch. But the drugs prolonged the elimination of their pain – turning the acute pain into something more chronic.
In the final phase of the study, they examined data on 500,000 people from the UK’s Biobank, a database of medical information obtained from half a million volunteers.
Researchers have found that those who take anti-inflammatory drugs such as ibuprofen, naproxen and diclofenac to treat their pain are much more likely to experience pain two to 10 years later – a correlation that is consistent with their other findings. but cannot determine what caused the continuing pain.
By comparing blood samples between patients whose pain was resolved and those who did not, the researchers found that people whose pain disappeared had experienced a lot of inflammation caused by neutrophils, a type of white blood cell. (Louis-Marie Filidore / CBC)
They also found that those taking other painkillers, such as acetaminophen (Tylenol), were less likely to have chronic pain than those taking anti-inflammatory drugs.
The study should be taken seriously, says the pain doctor
Dr. Hans Clark, medical director of the Toronto General Hospital’s pain research department, says about 18 percent of the population struggles with chronic back pain.
Even without randomized clinical trials, Clark said there were implications for understanding what happens differently between acute and chronic pain.
“This is a very remarkable finding,” he told CBC News.
“Finding a molecular basis that applies to those who will have a problem with chronic pain compared to those who will avoid it must be taken quite seriously.”
Clark says the main treatment for a back injury should be heat, physiotherapy, stretching, massage and then potentially medication.
“What these researchers showed was that, you know, we could try other drugs other than anti-inflammatory ones first,” he said.
Dr Hans Clark, director of pain services at Toronto General Hospital, says the study has findings that need to be taken seriously when it comes to chronic pain. (Dr. Hans Clark)
Clark says he has a natural immune response that must occur after an injury.
“We still need to really understand when we need to intervene in this natural process, because it is clearly shown that if you have a large number of these white cells … that you can actually do better in the long run,” he said.
But until the results are tested in human trials, Clark still advises patients who can’t get out of bed because of pain to take anti-inflammatory drugs to help them function again.
“We don’t want the message to be… you have to be in excruciating pain for a long time because it’s a natural process,” he said.
A clinical trial is pending
Clark says about 90% of people with acute injuries will find that their pain goes away.
Stephen Katz, who lives in Toronto, is in the other 10 percent; he has had low back pain for years and a simple action such as lifting a pencil can cause an exacerbation.
Steve Katz suffers from chronic low back pain. With the results of this study, he says he can wait longer before resorting to anti-inflammatory drugs during his next exacerbation. (Mark Bohsler / CBC)
“It’s kind of a stabbing pain and it gets to the point where I really can’t walk,” he said.
Katz visits his physiotherapist Lauren Roberts often for exercise and acupuncture. But on days when he can’t get out of bed, he reaches for drugs like Robax and Advil.
Now that he has heard of the study, Katz says he can wait longer before taking his painkillers.
“I’m not surprised. At the same time, I’m allergic to pain,” he said. “It depends on the level of pain, to be honest.”
Roberts, who founded the Running Physio Clinic in Toronto, said she was also not surprised by the study’s findings – especially since similar discussions are taking place in the field of sports medicine. in 2015.
Physiotherapist Lauren Roberts, who founded the Running Physio Clinic in Toronto, says sports medicine is also discussing the positive role that inflammation can play in treatment. (Mark Bohsler / CBC)
“It is possible that there will be a negative side effect of taking NSAIDs [non-steroidal anti-inflammatory drugs], especially earlier in this inflammatory cycle that occurs in the body. But people tend not to like to hear that, Roberts said.
“This first 24 to 48 [hours]I would say, if you can overcome it, try and see if you can. ”
Mogil says the team is preparing to confirm its work randomized controlled trials with people.
“What we are saying here is quite radical.” It has been repealing decades of standard practice and exceptional claims require exceptional evidence, “he said.
“Before, we were mainly interested in what causes pain, and all the research was on that, but now I think more people are realizing that maybe it’s a better idea to try to understand why the pain goes away.”
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