Evaluating the pain in a subject is fundamental to ensure the best therapy. But how to do this, since this is influenced by many subjective factors? Currently, there are various scales of assessment that are divided into one dimensional, which measure only the intensity of pain, or multidimensional, which take into account various aspects but, due to their greater complexity, do not have wide use. An example of a one-dimensional scale is the visual analogue scale (VAS): the patient is invited to identify his or her own level of pain on a 10 cm long line in which the extreme to the left (0) corresponds to the absence of pain, while the extreme to the right (10) corresponds to the maximum pain imaginable.
With the intention of a more objective assessment of pain, Brown University researchers developed an electroencephalography-based test, i.e. detecting brain activity through electrodes placed on the scalp, with excellent temporal resolution.
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 an agreement about pain level so it is better managed and diagnosed, which may reduce the over-prescription of opioids.
~ Carl Saab, an associate professor of neuroscience and neurosurgery at Brown University
According to the research published in Scientific Reports, it would be possible to assess pain through the analysis of the power of theta waves, brain waves that have a bandwidth between 4 and 8 Hz. Moreover, using EEG, the evaluation would remain completely non-invasive.
During laboratory tests on rodents, researchers compared the EEG-based test with the one traditionally used to measure pain and the efficacy of painkillers in pre-clinical studies. The traditional consists of hitting the animal’s paw and seeing how quickly it moves away. Slow removal of the leg is linked to less pain and better pain-relieving therapy, whereas faster removal indicates the opposite.
The experiment was performed using three different pain medications on rats with sciatica. According to Saab, the two tests showed similar results overall.
However, in some specific cases, such as the decrease in the dose of the first drug, the first method was more precise and consistent with what resulted from clinical practice and, above all, managed to avoid false positives, something that did not happen with the behavioral test.
The final objective is to carry out a test that can be widely used and can improve the treatment of chronic pain. Such a test could also be effective for patients with communication difficulties, including young children, and find application in the veterinary field.