Researchers recorded brain impulses in patients who experienced continuous pain. The findings offer clues about future mechanisms for predicting and even erasing pain
Researchers first recorded patterns of nerve impulses in the brain of a person who is under chronic painpaving the way for implanted devices that can predict pain signals in the future or even override the mechanism.
Using a pacemaker-like device surgically placed inside the brain, the scientists recorded the brain impulses of four patients who suffered from uninterrupted nerve pain for over a year. The devices recorded several times a day for up to six months, offering clues as to where the chronic pain is located in the brain.
The study, published in the journal Nature Neurosciencereported that the pain was associated with electrical fluctuations in the orbitofrontal cortex, an area involved in emotion regulation, self-assessment and decision-making. Research suggests that such brain activity patterns could serve as biomarkers to guide the diagnosis and treatment of millions of people with chronic nervous system pain.
“The study truly advances a whole generation of research that has shown that brain function is important for pain processing and perception,” said Dr. Ajay Wasan, a pain medicine specialist at the University of Pittsburgh School of Medicine, who was not involved in the study.
About 1 in 5 American adults feel it chronic pain, which is defined as persistent or recurring pain that lasts for more than three months. To measure pain, doctors usually rely on patients’ self-ratings, using a numerical or visual scale with emojis. But the pain measures expressed by patients are subjective and can vary throughout the day. And some patients, such as children or people with disabilities, sometimes have trouble communicating their pain accurately.
“There’s a big movement in the pain field to develop more objective pain markers that can be used in conjunction with self-reports,” said Kenneth Weber, a Stanford University neuroscientist who was not involved in the study. In addition to advancing our understanding of what neural mechanisms underlie pain, Weber added, these markers could help validate pain experienced by some patients that is not fully recognized — or even completely ignored — by their physicians.
Previous studies have typically scanned the brains of chronic pain patients to look for changes in blood flow to various regions, an indirect measure of brain activity. But this type of research is limited to laboratory settings and requires patients to visit a hospital or laboratory multiple times.
In the new study, Dr. Prasad Shirvalkar, a neurologist at the University of California, San Francisco, and his colleagues used the electrodes to measure the collective firing pattern of thousands of neurons in the vicinity of the electrodes.
The researchers surgically implanted the devices into four people who had been living with pain for more than a year and found no relief from the medications. For three of the patients, the pain started after a stroke. The fourth had so-called phantom limb pain after losing a leg.
At least three times a day, patients rated the pain they were feeling and then pressed a button that stimulated their implants to record brain signals for 30 seconds. With patients being followed up daily at home and at work, “this is the first time we’ve assessed chronic pain in the real world,” Shirvalkar said.
The researchers placed electrodes in two areas of the brain: the orbitofrontal cortex, which hadn’t been studied much in pain research, and the anterior cingulate cortex, a region involved in processing emotional signals. Many studies have suggested that the anterior cingulate cortex is important for perceiving acute and chronic pain.
The scientists loaded data from patients’ pain scores and corresponding electrical signals into machine learning models, which could then predict chronic high and low pain states based on brain signals alone.
The researchers found that certain frequency fluctuations in the orbitofrontal cortex were the best predictors of chronic pain. While this brain signature was common among patients, Shirvalkar said, each patient also had unique brain activity. “Every patient had a different fingerprint for their pain,” he said.
Given these variations and the small number of study participants, Tor Wager, a Dartmouth College neuroscientist who was not involved in the study, advised caution before classifying orbitofrontal cortex signatures as biomarkers.
“We definitely need to corroborate this with other studies, using other methodologies that can provide systematic whole-brain coverage,” he said.
The study authors also noted that other brain regions may be involved. “We’re just getting started,” said Dr. Edward Chang, a neurosurgeon at the University of California, San Francisco. “This is only the first chapter.”
Implants also have another purpose: deep brain stimulation. As part of a larger clinical trial for the treatment of chronic pain, Shirvalkar and his colleagues are using mild electrical currents to stimulate brain regions near the electrodes. In addition to the four patients in the study who are already receiving this experimental therapy, the researchers want to recruit two more people and, over time, expand the study to another twenty to thirty people. Researchers hope to relieve lingering pain by sending pulses through the electrodes to correct any abnormalities in brain activity.
This article was originally published in The New York Times. /TRANSLATION BY RENATO PRELORENTZOU
Source: Terra
Ben Stock is a lifestyle journalist and author at Gossipify. He writes about topics such as health, wellness, travel, food and home decor. He provides practical advice and inspiration to improve well-being, keeps readers up to date with latest lifestyle news and trends, known for his engaging writing style, in-depth analysis and unique perspectives.
