A new technique to erase pain – nerve cooling - has been developed in the USA. A thin strip of bio-absorbable material, inserted around the nerves, radically lowers the temperature and curbs painful stimuli.
Alternative pain therapy
For several decades, pain therapy has relied mainly on opioids (morphine and others), which are very effective, but have major side effects, and can trigger dangerous forms of addiction, especially if used carelessly. This is why researchers have been looking for possible alternatives for some time.
One of the most interesting is described in an article published in the journal Science by researchers at Northwestern University (USA), who have suggested a system not based on drugs, but on a special cold therapy. Cold, as we well know, alleviates painful stimuli (think of ice packs!) More specifically, US scientists have created a very thin elastic strip, made of bio-absorbable material, which is inserted around individual nerve bundles to gently wrap them and produce precise, targeted cooling that numbs them and blocks pain signals to the brain. When this device is no longer needed, it dissolves and is eliminated through the kidneys, without the need for surgery.
Like numb fingers
"Our technique," explains bioengineer John Rogers, coordinator of the study, "exploits processes a bit like those that cause fingers to become numb when cold. The implant makes it possible to produce that effect in a programmable way, directly and locally on the targeted nerves, even those deep within the surrounding tissue”'.
So how does the cooling work technically? The strip created by Northwestern University is no more than 5 millimetres wide, about the thickness of a sheet of paper, and can be inserted by neurosurgeons without particularly invasive operations. The device contains two tiny channels to induce cold. In one there is a cooling liquid (perfluoropentane), while the other contains dry nitrogen, an inert gas. The amount of these two substances can be regulated via an external mini-pump. When liquid and gas flow into a shared 'chamber' within the strip, a reaction occurs that causes the liquid to evaporate rapidly, creating a sharp drop in temperature.
During these operations, a tiny integrated sensor monitors the situation to prevent excessive cooling of the nerve, which could cause tissue damage. In tests on laboratory animals, an antalgic effect was immediately apparent.
A vast range of potential applications
For the moment, the prototype is not ready to be tested on humans, because many details still have to be refined, but when it is, if it is confirmed to alleviate pain, it will probably find immediate application.
For example, it could be used in amputations, which are always followed by intense pain, but also to combat the so-called ‘phantom limb syndrome’, which also causes severe pain sensations. The new device can actually also be used - according to the researchers - to avoid the post-surgical pain of many other operations. In addition, simple pumps (like those for insulin) to mix liquid and gas and to be used as needed, are being considered for cases of chronic pain.
In the past, other research centres had turned to cold (cryotherapy) for pain relief, using - for example - needles to inject substances that could drastically lower temperature. But these techniques could not reach specific nerves and cooled large areas of tissue, creating undesirable effects such as cell damage and inflammation. The system developed by Northwestern University, however, seems to have overcome these problems.
