A team of researchers, led by Carl Saab from Brown University and Rhode Island Hospital, has developed a new method that is claimed to objectively measure pain levels. The system uses electroencephalography (EEG) to identify oscillations in certain brainwaves that have been found to clearly correlate with commonly used pain assessment tools.

Despite some extraordinary scientific advances in the 21st century it's remarkable how primitive our current pain measurement tools are. From simply ranking pain between 0 and 10, to the commonly used visual analog scale that is literally just a spectrum of smiley faces spanning happy to sad, these self-reported measures offer doctors no clear empirical way to evaluate a patient's pain levels.

Recent research has revealed that certain resting state EEG oscillations within the low-frequency theta band could be associated with pain levels. In order to home in on this specific association a new study measured the effectiveness of several pain medications in a rodent model, comparing EEG theta levels with a traditional behavior test.

The current way researchers measure pain, and the efficacy of pain medication, in animal models is to poke the animal's paw. If the animal withdraws its paw quickly it is regarded as a sign of high pain levels and ineffective medication. The new study revealed that EEG theta wave measurements could be clearly correlated with the results of this animal behavior test in evaluating an animal's pain levels.

In some cases the EEG results were notably more accurate than the animal behavior test, revealing certain doses of pain medication to be ineffective despite a slow paw response, suggesting the behavior test indicated a false positive.

One of the most helpful outcomes to potentially flow out of this research is the ability for clinicians to hopefully better evaluate pain levels in patients that are unable to clearly self-report those specific sensations. Young children, babies, and even animals, could be viable targets for this new EEG test, as the researchers are currently working to calibrate these EEG signatures in a way that correlates with traditional pain measurement scales. Following from that, the goal of the research is to develop new pain sensors that can easily and clearly signal to doctors how much pain a patient is actually suffering.

"Our goal is to associate specific brain activity with various scores on the numerical scale to make pain assessment more objective," explains Carl Saab, a researcher working on the project. "We want to help patients with chronic pain and their physicians get into agreement about pain level so it is better managed and diagnosed, which may reduce the over-prescription of opioids."

The new study was published in the journal Scientific Reports.