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Hydrophilic Polymers Allow Immediate Physiologic Function of Severed Nerves after Interposition Grafting
Kevin W. Sexton, MD; G. A. Del Corral, MD; J. M. Britt; G. D. Bittner, PhD; R. B. Shack, MD; W. P. Thayer, MD, PhD
Vanderbilt University, Nashville, TN, USA
Background: Traumatic neuropathies (TN) are a common source of morbidity in the United States affecting approximately 5% of all admissions to a level one trauma center. It has been reported that less than 50% of these injuries will obtain a functional recovery and less than 5% will obtain a full recovery. We sought to improve the rate of physiologic recovery following repair of transected nerves using hydrophilic polymers. This technique is based on the ability to fuse axons of severed cell membranes using hydrophilic polymers, generating functional and morphological neuronal continuity. Our hypothesis is that nerve gaps can be acutely repaired using autografts and a double fusion technique if performed before the onset of Wallerian degeneration. Our technique may be applicable for cases of segmental nerve loss including patients with acute traumatic deficits and also patients in need of reconstruction after oncologic resection.
Methods: Sprague Dawley rats were anesthetized with isoflourane. The right sciatic nerve was exposed. Baseline compound action potentials (CAPs) were stimulated and recorded using a Powerlab data acquisition system (ADInstruments). A 0.5 cm segment of the sciatic nerve was then removed with scissors. The transected nerve segment was then reimplanted in an end-to-end fashion using an epineural approximation technique. CAPS were recorded as above. A series of solutions (Calcium free Kreb’s solution [0.5 mM EGTA in 99 mM NaCl, 5 mM KCl, 1.2 mM KH2PO4, 1.3 mM MgSO4, 26 mM NaHCO3, 10 mM Na ascorbate, 10 mM dextrose, pH 7.35, 295 milliosmolar], 1 mM Methylene Blue in Calcium free Kreb’s solution, and 190 mM Polyethylene glycol 3.35 kD in distilled water) were applied to the repair sites. After 3 minutes, solution CAPS were obtained in the same manner above.
Results: Three interposition grafts were performed. Prism 5, (GraphPad Software, Inc.) was used for all data comparisons. Baseline CAPs had average amplitude of 2.771 +/- 1.2 mV. No CAPs could be obtained after standard epineural repair (0 +/- 0 mV). After solution exposure, post repair CAPs were obtained with a mean of 3.726 +/- 2.309 mV. Baseline CAPs and post solution exposure CAPs were not significantly different (p=.5304, paired t-test).
Conclusions: Hydrophilic polymers allow for immediate return of physiologic function in a short segment nerve interposition graft
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