Miniature, implantable nerve coolers for targeted pain relief

An implantable device designed to “cool” nerves can provide targeted, on-demand pain relief, researchers report. When tested on rats with neuropathic pain, the device produced highly localized cooling. “An implantable cooling device with on-demand local analgesia will be a game changer for long-term pain management,” write Shan Jiang and Guosong Hong in a related Perspective. It offers a promising path toward creating a class of analgesic devices for long-term, nonopioid pain management. Pain management is a pressing health issue for many, who often must turn to effective yet highly addictive and sometimes deadly opioid pain medications. This has made the development of localized, nonopioid, and nonaddictive alternatives highly attractive. One such approach is analgesic nerve cooling, which holds promise as an effective and reversible way to alleviate pain, including after amputations, nerve grafts, or spinal decompression surgeries, as examples. Like putting ice on a sore joint or muscle, targeted application of cold temperature directly to nerves can block the conduction of pain signals, providing temporary relief. However, conventional nerve cooling devices are bulky and rigid with non-specific cooling and high power requirements – qualities that prevent practical clinical use. To address this, Jonathan Reeder and colleagues developed a soft, miniaturized, and implantable nerve cooling system based on state-of-the-art microfluidic and flexible electronic technologies. Borrowing from electrical nerve cuffs, Reeder et al. use a liquid-to-gas phase transition within microfluidic channels in an elastic band that wraps around peripheral nerves to provide targeted cooling. An integrated thermal thin film sensor in the device provides real-time temperature monitoring and control. Since the device is made from water-soluble and biocompatible materials, it is bioresorbable (meaning it degrades), reducing necessary surgery risk. To demonstrate the device’s ability, the authors performed in vivo experiments in rat models of neuropathic pain, rapidly and precisely cooling peripheral nerves to provide local and on-demand pain relief. “Besides the demonstrated strengths of the miniaturized flexible cooling device for pain mitigation,” write Jiang and Hong in the related Perspective, “the technology presents further opportunities for neuroscience research and neurological practice.”