Researchers develop new test to objectively measure pain, test medications

November 6, 2018 by Mollie Rappe, Brown University
Credit: CC0 Public Domain

If you've ever visited the emergency department with appendicitis, or you're one of the 100 million U.S. adults who suffer from chronic pain, you're familiar with a row of numbered faces, with expressions from smiling to grimacing, used to indicate pain levels.

Despite that tool's widespread use, some researchers say a more empirical approach would better serve both patients and the physicians who provide care.

"Sadly, this scale of smiley faces, called the visual analogue scale, is the gold-standard pain-assessment tool," said Carl Saab, an associate professor of neuroscience and neurosurgery (research) at Brown University and Rhode Island Hospital. "Our goal is to associate specific brain activity with various scores on the numerical scale to make pain assessment more objective. 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."

Saab and his colleagues have developed an electroencephalography-based test to objectively measure pain. Electroencephalography (EEG) is a method that measures brain activity using electrodes placed on the scalp. The brain activity is measured in the form of oscillations or "waves" of a certain frequency, somewhat like the specific frequency that dictates a radio station.

A frequency that correlates with pain in animals is called the "theta band," Saab said. Computational analysis of theta brain waves to determine their power can be used to objectively measure pain in rodents and humans in a non-invasive manner, he added.

In a Nov. 6 paper published in Scientific Reports, Saab's team reported that measuring the power of theta waves using EEG is an effective and direct test of pain and potential pain medication efficacy in pre-clinical animal models.

Testing new pain medications

The current method to measure pain, and the effectiveness of potential pain medications, in a pre-clinical animal model is to poke the animal's paw and see how quickly it moves its paw away. Slow paw withdrawal is linked to less pain and better pain medication. Faster paw withdrawal is linked to more pain and less effective pain medication.

"When I was a graduate student, I hated this test because it had nothing to do with clinical pain," said Saab, who is affiliated with Brown's Carney Institute for Brain Science. "Nobody pokes a patient with back pain. I'm just so happy that I beat this test, now we're working with something better."

Since the EEG-based test is a more direct measure of ongoing, spontaneous pain than the current approach, it could help researchers develop more effective medications for chronic back pain or sciatica, which don't have many effective treatments, Saab said.

In the paper, his team looked at three pain medications and compared their effectiveness in an animal model of sciatica. The researchers used the traditional behavior test, the EEG test and an analysis to determine blood concentration of the medications, which was compared with the clinical blood concentration of the medications in human patients.

The first medication they tested was a proven treatment for some forms of chronic pain, which is sold under the brand name Lyrica. The second was a promising in phase two clinical trials, and the third was a medication with inconclusive effectiveness in earlier studies.

Overall, the theta wave measurement and behavior test gave similar results, said Saab.

However, for a few of the experiments, such as a dose below the effective level of the first , the EEG test provided results that were more accurate—more similar to the results found in patients than the behavior test—said Saab. Specifically, the EEG test showed a decrease in theta power measurement at the clinical dose but not the low dose, while the behavior test showed slower paw withdrawal at the low dose and the clinical dose. By indicating pain relief at a dose lower than the effective dose, the behavior test gave a false positive.

"The ability to detect false positive or false negative outcomes is crucial to the drug development process," the authors wrote. Saab believes that the EEG test can aid researchers in identifying false positives in pre-clinical trials of new pain medications, improving the development process.

Future impact of pain test

The ultimate goal of the research is an objective tool to measure pain for clinics and emergency departments. Toward this end, Saab is working to translate his findings to patients by calibrating the EGG signatures of pain with the traditional smiley-face-based tool.

In addition to aiding the development of more effective pain medications and improving the diagnosis and management of chronic pain, both of which address contributing factors to the opioid epidemic, an objective measure of pain could improve health disparities, Saab said. These range from women whose pain is dismissed by medical practitioners to patients with difficulty communicating, including young children.

Three years ago, Saab launched a start-up company to develop the next generation of pain sensors, which he hopes can become the new gold standard for pain measurement. Saab added there's considerable interest in a pain measurement tool for veterinary medicine.

Saab and Brown collaborators David Borton, an assistant professor of engineering, and Stephanie Jones, an associate professor of neuroscience, are working to understand the fundamental neuroscience of and what kind of activity in the neurons produces the brain waves that constitute "signatures" of pain. In September, the team received a BRAIN grant from the National Institutes of Health to support this work.

Saab presented his findings on the EGG to determine the effectiveness of new medications on Monday, Nov. 5, at the annual convention of the Society for Neuroscience in San Diego.

Explore further: CDC: about one in five U.S. adults have chronic pain

More information: Suguru Koyama et al, An Electroencephalography Bioassay for Preclinical Testing of Analgesic Efficacy, Scientific Reports (2018). DOI: 10.1038/s41598-018-34594-2

Related Stories

CDC: about one in five U.S. adults have chronic pain

September 14, 2018
(HealthDay)—About 20.4 percent of U.S. adults have chronic pain and 8.0 percent have high-impact chronic pain, according to research published in the Sept. 14 issue of the U.S. Centers for Disease Control and Prevention's ...

Study IDs pain descriptors for varying stages of low back pain

May 4, 2018
(HealthDay)—Varying pain descriptors may be useful when evaluating patients with different stages of low back pain (LBP), according to a study published online April 30 in PAIN Practice.

Study finds the frequency of alpha brain waves could be used to assess a person's predisposition to pain

March 28, 2018
The frequency of alpha brain waves can be used as a measure of an individual's vulnerability to developing and experiencing pain, researchers at the University of Birmingham in the UK and University of Maryland in the US ...

Animations prove effective in accurately measuring pain

August 6, 2018
To improve communication about pain between patients and physicians, a team led by researchers from the University of Pittsburgh and UPMC has developed a mobile application called "Painimation" that has the potential to assess ...

Reduction of opioid dose may improve pain, quality of life

July 20, 2017
(HealthDay)—Reductions in opioid dosing might improve pain and function, as well as boost quality of life, according to a report published online July 18 in the Annals of Internal Medicine.

Hypnosis transforms treatment for chronic pain

May 16, 2018
Researchers from UNSW Sydney and Neuroscience Research Australia (NeuRA), Universidade Cidade de São Paulo, Brazil and the University of Washington, US have identified a new drug-free treatment which combines hypnosis with ...

Recommended for you

Infants born to obese mothers risk developing liver disease, obesity

November 16, 2018
Infant gut microbes altered by their mother's obesity can cause inflammation and other major changes within the baby, increasing the risk of obesity and non-alcoholic fatty liver disease later in life, according to researchers ...

New study shows NKT cell subsets play a large role in the advancement of NAFLD

November 16, 2018
Since 2015 it has been known that the gut microbiota could have a direct impact on nonalcoholic fatty liver disease (NAFLD), which affects up to 12% of adults and is a leading cause of chronic liver disease. In the November ...

Antibiotic prescribing influenced by team dynamics within hospitals

November 15, 2018
Antibiotic prescribing by doctors is influenced by team dynamics and cultures within hospitals.

Discovery suggests new route to fight infection, disease

November 14, 2018
New research reveals how a single protein interferes with the immune system when exposed to the bacterium that causes Legionnaires' disease, findings that could have broad implications for development of medicines to fight ...

Zika may hijack mother-fetus immunity route

November 14, 2018
To cross the placenta, Zika virus may hijack the route by which acquired immunity is transferred from mother to fetus, new research suggests.

New research aims to help improve uptake of hepatitis C testing

November 14, 2018
New research published in Scientific Reports shows persisting fears about HIV infection may impact testing uptake for the hepatitis C Virus (HCV).

2 comments

Adjust slider to filter visible comments by rank

Display comments: newest first

SANDROGREG
not rated yet Nov 07, 2018
God bless Dr Larry for his marvelous work in my life, I was diagnosed of HERPES SIMPLEX VIRUS since 2010 and I was taking my medications, I wasn't satisfied i needed to get the HERPES out of my system, I searched about some possible cure for HERPES i saw a comment about Dr Larry, how he cured HERPES with his herbal medicine, I contacted him and he guided me. I asked for solutions, he started the remedy for my health, he sent me the medicine within 3days. I took the medicine as prescribed by him and 2weeks later i was cured from HERPES contact him assurancesolutionhome@gmail.com once again thanks to you Dr Larry. cure the flowing virus, contact his web site: or add him on whatsapp +1(424)-261-8520
1 cancer cure
2 diabetes cure
3 ringing ear
4 herpes cure
5 warts cure
6 HPV cure
7 HIV
8 get your ex back
9 pregnancy herbal medicine
10 prostate enlargement
11 Hepatitis
SANDROGREG
not rated yet Nov 07, 2018
God bless Dr Larry for his marvelous work in my life, I was diagnosed of HERPES SIMPLEX VIRUS since 2010 and I was taking my medications, I wasn't satisfied i needed to get the HERPES out of my system, I searched about some possible cure for HERPES i saw a comment about Dr Larry, how he cured HERPES with his herbal medicine, I contacted him and he guided me. I asked for solutions, he started the remedy for my health, he sent me the medicine within 3days. I took the medicine as prescribed by him and 2weeks later i was cured from HERPES contact him assurancesolutionhome@gmail.com once again thanks to you Dr Larry. cure the flowing virus, contact his web site: assurancesolutionhome.wordpress.com
assurancesolutionhome.website2.me/ or add him on whatsapp +1(424)-261-8520
1 cancer cure
2 diabetes cure
3 ringing ear
4 herpes cure
5 warts cure
6 HPV cure
7 HIV
8 get your ex back
9 pregnancy herbal medicine
10 prostate enlargement
11 Hepatitis

Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.