Researchers have identified two biomarkers that can reveal how sensitive an individual is to pain, and may offer new approaches for treating pain. Reporting in JAMA Neurology, scientists found that measurements of corticomotor excitability (CME), which happens in a part of the brain that helps control movement, and peak alpha frequency (PAF), which is linked to cognitive performance, can reliably differentiate between people with high and low thresholds to pain over long periods. With these biomarkers, people with varying levels of sensitivity to pain might be able to receive better treatments that are more tailored to their needs.
"The burden of chronic pain is massive. Having objective biomarkers would greatly assist with decision making in the diagnosis, prevention and treatment of chronic pain," said senior study author David Seminowicz, now of the University of Western Ontario.
Chronic pain affects almost two billion people around the world, which has a dramatic effect on their quality of life. There is also a need for better, nonaddictive therapeutics.
In this study, the investigators focused on people with pain in the muscles or joints around the jaw. This pain is usually associated with temporomandibular disorders. The researchers measured PAF levels with electroencephalography (EEG). This technique uses electrodes to record the brain's electrical activity. CME was measured with a tool called transcranial magnetic stimulation, which uses magnetic fields to stimulate neurons in the brain.
"For the first time we have something that looks like it could predict pain outcomes for people," said study co-author Siobhan Schabrun, a professor at the University of Western Ontario, among other appointments.
The work indicated that people with a slow PAF before lengthy pain episodes and reduced CME levels after the onset of prolonged pain would be more likely to have higher levels of pain after days or weeks.
Individuals with low CME levels during acute lower back pain were also at higher risk of chronic pain after six months.
It may also be possible to measure PAF and CME levels before surgery so that clinicians know which patients will be more sensitive to pain afterwards.
"This study represents a major leap forward in the field of pain science. A biomarker that can predict pain sensitivity with 88 percent accuracy has the potential to transform the treatment and prevention of pain in future," noted Schabrun.
Now, the investigators want to validate the reliability and accuracy of these biomarkers in larger populations, and develop clinical applications for these tests.
"If these brain biomarkers can predict that occurrence in future, we hope to be able to interfere with the transition to chronic pain to provide better patient outcomes," said Schabrun.
Sources: University of Western Ontario, JAMA Neurology