Polyethylene-Glycol Assisted Nerve Repair Promotes Superior Sensory and Motor Recovery Following Injury of Mixed Sensory-Motor Nerves in the Upper Extremities
Sriya V Nemani, BA1, Sara C Chaker, BS1, Helene Ismail, MSc1, Jun Yao, RN1, Douglas Weikert, MD1, Mihir J Desai, MD1, Jed Ian Maslow, MD1, Brinkley K Sandvall, MD2, Panambur Laxminarayan Bhandari, MD1, William Lineaweaver, MD1, Brian C Drolet, MD1, J. Bradford Hill, M.D.1 and Wesley P. Thayer, M.D., PhD1, 1Vanderbilt University Medical Center, Nashville, TN, 2Texas Children's Hospital, Houston, TX
Introduction. In more proximal injuries of mixed sensory-motor nerves, delayed nerve regeneration can cause debilitating muscle atrophy and can result in the amputation of the affected extremity, significantly decreasing the patient’s quality of life. Polyethylene-glycol (PEG), through its hydrophilic properties, can facilitate the fusion of severed axons. Topical application of PEG during nerve repair prevents axonal degeneration, restores the morphological continuity of the severed axon, and promotes immediate conduction of action potentials across the nerve coaptation site. PEG-fusion of rat sciatic nerves has been shown to increase the number of surviving neuromuscular junctions, reduce muscle atrophy, and improve functional outcomes. Currently, there are no human studies on PEG-fusion in mixed sensory-motor nerve injuries.
Materials and Methods. This study presents preliminary data from our clinical trial on PEG-fusion, comparing patients treated with PEG with historical controls. Patients with completely transected median or ulnar nerves which could be repaired within 72 hours of injury were enrolled and treated with our novel PEG-fusion protocol. Participants followed up at 2 weeks, 1 month, 3 months, 6 months, and 1 year postoperatively. Sensory recovery was assessed at each timepoint using Semmes-Weinstein monofilaments and static two-point discrimination testing. A Medical Research Council Classification (MRCC) rating was then calculated from the respective sensory assessments. Motor function was assessed at each timepoint using the MRCC ratings as well, which were determined by clinician assessment. Participants were compared to demographically matched patients previously treated at our institution for ulnar or median nerve injuries.
Results. A total of 18 patients (6 PEG, 12 control) with a total of 20 transected nerves (10 median, 10 ulnar) were analyzed. Demographic and surgical characteristics, including the distance from the fingertip to the injury, did not significantly differ between groups. Patients treated with PEG demonstrated significantly greater sensation at 2 weeks (p < 0.000), 1 month (p < 0.000), 3 months (p < 0.000), 6 months (p < 0.000), and 1 year (p = 0.028) compared to historical controls. Patients in both cohorts demonstrated similar MRCC motor scores in the early postoperative period, however at 1 year postoperatively PEG patients significantly outperformed their control counterparts in motor function (p < 0.000). No participants had adverse events related to the study drug.
Conclusion. PEG-fusion accelerates sensory recovery following the repair of a mixed sensory-motor nerve. PEG-fusion also allows for superior motor function later in recovery, likely by preserving neuromuscular junctions and preventing muscle atrophy.
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