Researchers developing dissolving pain-relief implant

A Northwestern University-led team of researchers has developed an implant that relieves pain on demand without the use of drugs. The water-soluble device wraps around nerves to deliver targeted cooling, which numbs nerves and blocks pain signals to the brain. The patient uses an external pump to remotely activate the device and adjust its intensity. After the device is no longer needed, it naturally absorbs into the body. “Although opioids are extremely effective, they also are extremely addictive,” said engineer John A. Rogers, who is the Louis Simpson and Kimberly Querrey Professor of Materials Science and Engineering, Biomedical Engineering and Neurological Surgery in the McCormick School of Engineering and Northwestern University Feinberg School of Medicine. “The technology reported here exploits the mechanism that causes your fingers to feel number when cold. Our implant allows that effect to be produced in a programmable way, directly and locally to targeted nerves, even those deep within surrounding soft tissues.” Read: Atopic dermatitis: a new treatment approved by Health Canada The new device leverages a simple, common concept that everyone knows: evaporation. Similar to how evaporating sweat cools the body, the device contains a liquid coolant that is induced to evaporate at the specific location of a sensory nerve. “As you cool down a nerve, the signals that travel through the nerve become slower and slower — eventually stopping completely,” said study coauthor Dr. Matthew MacEwan of Washington University School of Medicine in St. Louis. “We are specifically targeting peripheral nerves, which connect your brain and your spinal cord to the rest of your body. These are the nerves that communicate sensory stimuli, including pain. By delivering a cooling effect to just one or two targeted nerves, we can effectively modulate pain signals in one specific region of the body.” The device is just 5 millimeters wide. One end is curled into a cuff that softly wraps around a single nerve, bypassing the need for sutures. By precisely targeting only the affected nerve, the device spares surrounding regions from unnecessary cooling, which could lead to side effects. “You don’t want to inadvertently cool other nerves or the tissues that are unrelated to the nerve transmitting the painful stimuli,” MacEwan said. “We want to block the pain signals, not the nerves that control motor function and enables you to use your hand, for example.” To induce the cooling effect, the device contains tiny microfluidic channels. One channel contains the liquid coolant (perfluoropentane), which is already clinically approved as an ultrasound contrast agent and for pressurized inhalers. A second channel contains dry nitrogen, an inert gas. When the liquid and gas flow into a shared chamber, a reaction occurs that causes the liquid to promptly evaporate. Simultaneously, a tiny integrated sensor monitors the temperature of the nerve to ensure that it’s not getting too cold, which could cause tissue damage. “Excessive cooling can damage the nerve and the fragile tissues around it,” Rogers said. “The duration and temperature of the cooling must therefore be controlled precisely. By monitoring the temperature at the nerve, the flow rates can be adjusted automatically to set a point that blocks pain in a reversible, safe manner.” The researchers believe the device will be most valuable for patients who undergo routine surgeries or even amputations that commonly require post-operative medications. Surgeons could implant the device during the procedure to help manage the patient’s post-operative pain. The study, “Soft, bioresorbable coolers for reversible conduction block of peripheral nerves,” was supported by the Phil and Penny Knight Campus for Accelerating Scientific Impact, the Querrey Simpson Institute for Bioelectronics, and the National Science Foundation (award number CMM1635443). It will be published in the July 1 issue of the journal Science. Read: QUIZ: Puzzles in chronic pain management This article was originally published in Convenient Care Clinician.

Researchers developing dissolving pain-relief implant

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