Nerve Tape-Assisted PEG Fusion
Abstract
Peripheral nerves are the “wires” of the body that carry electrical signals from the brain to the muscles (telling them what to do) and from the skin back to the brain (for interpretation of sensation). Severe nerve injuries often result in life-altering functional deficits including loss of ability to elicit volitional movement in part or all of a limb. Soldiers with these types of injuries rarely return to active duty. When a nerve is transected, the only hope for recovery is surgical repair. Using the “wire” analogy, after a nerve is cut, the “copper” degenerates within a few days and is cleared by the body leaving an empty tube of “insulation.” Historically, fixing a cut nerve required a specially trained surgeon using microsutures thinner than a human hair to sew the “insulation” together and provide a path for the “copper” to regrow along. This regenerative process is very slow, inefficient, and almost always unsatisfactory. The copper wires (really many microscopic nerve fibers) often cannot find their way to the muscle and are lost. However, even with successful regrowth, time dependent irreversible changes leave the target muscles permanently weakened and clinical outcomes tend to be dismal. Several decades ago, it was discovered that cut nerve ends could spontaneously anneal when treated with a series of solutions including a specific form of polyethylene glycol (PEG) hydrogel. Instead of the “copper” degenerating and necessitating the slow, inefficient process of regrowth, the copper ends could be welded back together—re-establishing immediate conductivity and avoiding many of the pitfalls of the regeneration process including muscle weakening. Starting with earthworms and simple biological models but working up to small animals, researchers developed and gradually refined this technique so that, when done properly, functional recovery was not only faster but also remarkably better. Unfortunately, there are significant obstacles to translating this technique to clinical practice: (1) the repair must be done within one to three days from the time of injury; (2) the approximated nerve ends must be precisely aligned; and (3) the repair must be stabilized to protect the fragile “spot welds” until they have time to mature. Obtaining perfect alignment is difficult for even specialized surgeons when using conventional microsuture techniques, and less experienced surgeons are often not capable of consistently achieving successful “PEG-fusion.” Experienced microsurgeons tend to be at specialized centers that may be logistically difficult and time-expensive to access. Nerve Tape is a novel nerve repair device that utilizes microhooks (less than ½ a millimeter long) embedded into a biologically friendly backing. Though currently developed for conventional nerve repair, Nerve Tape has several characteristics that make it well suited to facilitate PEG-fusion: (1) it is easy to use (the Nerve Tape is positioned with the microhooks facing up so that the nerve ends can be positioned perfectly apposed; the microhooks engage the outer surface of the nerve without damaging the sensitive internal structures); (2) the Nerve Tape entubulates the repair, directing the ends toward each other and fine-tuning and achieving precise alignment; and (3) the metal scaffold and wrapping combined with the microhooks provides stability and protection to fragile, repaired nerve fibers. The purpose of our proposed study is to (1) modify Nerve Tape design to facilitate the PEG-fusion process; (2) validate the efficacy of Nerve Tape facilitated PEG-fusion in both small and larger nerves; and (3) ensure that the optimized tool/protocol is effective even when used by less experienced surgeons. Based on preliminary work in our laboratory, the microhooks must be repositioned and windows or fenestrations created at the nerve coaptation to increase nerve end stability and provide access for direct solution/PEG application. These
Document Details
- Document Type
- DoD Grant Award
- Publication Date
- Dec 05, 2021
- Source ID
- W81XWH2110825
Entities
People
- Jonathan Isaacs
Organizations
- United States Army
- Virginia Commonwealth University