title: Hydrophilic polymers enhance early functional outcomes after nerve autografting.
abstract: BACKGROUND
  Approximately 12% of operations for traumatic neuropathy are for patients with segmental nerve loss, and less than 50% of these injuries obtain meaningful functional recovery. Polyethylene glycol (PEG) therapy has been shown to improve functional outcomes after nerve severance, and we hypothesized this therapy could also benefit nerve autografting.
  
  
  METHODS
  We used a segmental rat sciatic nerve injury model in which we repaired a 0.5-cm defect with an autograft using microsurgery. We treated experimental animals with solutions containing methylene blue (MB) and PEG; control animals did not receive PEG. We recorded compound action potentials (CAPs) before nerve transection, after solution therapy, and at 72 h postoperatively. The animals underwent behavioral testing at 24 and 72 h postoperatively. After we euthanized the animals, we fixed the nerves, sectioned and immunostained them to allow for quantitative morphometric analysis.
  
  
  RESULTS
  The introduction of hydrophilic polymers greatly improved morphological and functional recovery of rat sciatic axons at 1-3 d after nerve autografting. Polyethylene glycol therapy restored CAPs in all animals, and CAPs were still present 72 h postoperatively. No CAPS were detectable in control animals. Foot Fault asymmetry scores and sciatic functional index scores were significantly improved for PEG therapy group at all time points (P < 0.05 and P < 0.001; P < 0.001 and P < 0.01). Sensory and motor axon counts were increased distally in nerves treated with PEG compared with control (P = 0.019 and P = 0.003).
  
  
  CONCLUSIONS
  Polyethylene glycol therapy improves early physiologic function, behavioral outcomes, and distal axonal density after nerve autografting.
authors.affiliation: Department of Plastic Surgery, Vanderbilt University Medical Center, Nashville, Tennessee, USA. kevin.w.sexton@vanderbilt.edu
authors.forename: Kevin W
authors.initials: KW
authors.lastname: Sexton
authors.forename: Alonda C
authors.initials: AC
authors.lastname: Pollins
authors.forename: Nancy L
authors.initials: NL
authors.lastname: Cardwell
authors.forename: Gabriel A
authors.initials: GA
authors.lastname: Del Corral
authors.forename: George D
authors.initials: GD
authors.lastname: Bittner
authors.forename: R Bruce
authors.initials: RB
authors.lastname: Shack
authors.forename: Lillian B
authors.initials: LB
authors.lastname: Nanney
authors.forename: Wesley P
authors.initials: WP
authors.lastname: Thayer
mesh_terms: D000200:Action Potentials; D000818:Animals; D001369:Axons / Q000473:pathology; D001522:Behavior, Animal; D005260:Female; D005528:Foot / Q000502:physiology; D009416:Nerve Regeneration / Q000187:drug effects*; D016067:Nerve Transfer; D011092:Polyethylene Glycols / Q000494:pharmacology / Q000627:therapeutic use*; D051381:Rats; D017207:Rats, Sprague-Dawley; D012584:Sciatic Nerve / Q000502:physiology; D020426:Sciatic Neuropathy / Q000601:surgery*; D013501:Surface-Active Agents / Q000494:pharmacology / Q000627:therapeutic use*
chemical_list: D013501:Surface-Active Agents; D011092:Polyethylene Glycols