Soundwaves from low-intensity focused ultrasound reduce pain perception and associated cardiovascular effects. The corresponding study was published in Pain.
Focused ultrasound delivers a narrow band of sound waves to specific points inside tissues. It uses the same technology used to view babies developing in the womb. Whereas high-intensity ultrasound can ablate tissue, low-intensity waves have gentler effects, such as slowing nerve cell electrical activity. The approach has been used safely and effectively in both animal and human models, and is advantageous for noninvasively targeting deep structures.
Multiple studies suggest that the insula- an area located deeply within the brain- is critical for nociception and pain experience. In the current study, the researchers thus sought to see whether targeting the insula with focused ultrasound could ease pain. To do so, they recruited 23 healthy participants. They applied heat to the back of their hands to induce pain while delivering focused ultrasound waves to their insula guided by magnetic resonance imaging (MRI). They also monitored participant's heart rates and heart rate variability, and asked them to rate their pain perception on a scale of zero to nine.
Ultimately, the researchers found that the ultrasound reduced heart rate and heart rate variability- physical responses to the stress of pain. Meanwhile, participants reported an average pain reduction of three-quarters of a point. Study author Wynn Legon Ph.D., assistant professor at the Fralin Biomedical Research Institute at Virginia Tech, said in a press release:
"That might seem like a small amount, but once you get to a full point, it verges on being clinically meaningful. It could make a significant difference in quality of life, or being able to manage chronic Pain with over-the-counter medicines instead of prescription opioids."
The researchers noted that their work is a 'proof-of-principle study'. Future research directions include exploring the heart-brain axis, and whether pain can be mitigated by reducing the cardiovascular effects of stress.
Sources: Pain, Science Daily