Scientists have long struggled to understand the science behind pain. At present, most diagnoses rely on subjective methods, such as self-reporting from patients and physical examinations. But there is currently no existing method of measuring pain intensity objectively.
Pain is always a subjective experience, as no one really knows how much pain another person is feeling. What one person describes as agonizing, another may call excruciating.
Researchers from Stanford University say that at present, there is no scientific way to measure pain intensity objectively or to pinpoint its exact location. If a patient is reluctant or unable to describe their pain, it can lead doctors down blind alleys or make it difficult to ascertain how a treatment is working.
In their study, published in the Journal of the American Chemical Society, the scientists claim they have developed a new technique that could result in better ways to relieve pain and monitor healing. It may also help doctors pinpoint the exact location of pain.
Sodium channels and saxitoxin
Previous studies have shown a link between pain and a particular protein - called a sodium channel - that helps nerve cells transmit pain and other sensations to the brain.
Certain types of the voltage-gated sodium channels are produced in large quantities at the site of the injury, and the Stanford scientists decided to develop an imaging method that could visualize large concentrations of the protein.
By attaching a signal to a small molecule called saxitoxin - a naturally occurring molecule produced by certain types of microscopic marine creatures - scientists were able to track its progress through the body using PET imaging.
Testing their hypothesis on rats, the researchers discovered that the saxitoxin molecules pooled at the sites where rats had nerve damage.
The researchers claim this is one of the first attempts to mark these sodium channels in living animals.
The paper states:
"We envision using this type of PET agent for serial monitoring of changes in channel expression levels that occur at injured nerves as a function of wound healing and/or drug treatment. Such information may be correlated with pain behavioral analyses to help shed light on the complex molecular processes that underlie pain sensation."