“Ice on it!”: This is often the advice to relieve pain quickly. Depending on the injury, however, a lot of ice is needed, which also cools imprecisely when placed on the skin. A team from Northwestern University in the USA presented an alternative in Science magazine: an ultra-miniaturized ice bag that can be implanted and placed directly on a single nerve. It has been shown to relieve pain in rats, suggesting it may also be useful in treating pain in humans, they say.
The new gadget is interesting because of its size and nature. It’s made of a soft, stretchy, nerve-like material called polyoctanediol citrate, or POC for short, that gradually melts in the body. “Local cooling is an effective tool for relieving pain,” says Theanne Griffith, a neuroscientist at the University of California, Davis, who was not involved in the study. »The concept shows how this longstanding knowledge can be applied in a really innovative way.«
The method is based on tiny, snake-shaped tubes through which liquid flows and an electronic interface that measures and controls the temperature and thus nerve activity. The cooling takes place with the help of the chemical perfluoropentane (PFP) contained in the tubes, which is already approved in the USA as a contrast medium for ultrasound.
Another chamber contains dry nitrogen. When the two chemicals come together, they produce the desired cold. The device, just a few millimeters long, wraps a tiny section of a single nerve like a cuff and cools it directly. According to current knowledge, a second surgical procedure should not be necessary to remove the device, since it later dissolves in the body.