title: Functional regeneration of recurrent laryngeal nerve injury during thyroid surgery using an asymmetrically porous nerve guide conduit in an animal model.
abstract: BACKGROUND
  Vocal cord paralysis (VCP) caused by recurrent laryngeal nerve (RLN) damage during thyroidectomy commonly results in serious medico-legal problems. The purpose of this study was to evaluate the usefulness of an asymmetrically porous polycaprolactone (PCL)/Pluronic F127 nerve guide conduit (NGC) for functional regeneration in a RLN injury animal model.
  
  
  METHODS
  A biodegradable, asymmetrically porous PCL/F127 NGC with selective permeability was fabricated for use in this study. A 10-mm segment of left RLN was resected in 28 New Zealand white rabbits, and then an asymmetrically porous NGC or a nonporous silicone tube was interposed between both stumps and securely fixed. Vocal cord mobility was endoscopically evaluated at one, four, and eight weeks postoperatively. Nerve growth through NGCs was assessed by toluidine blue staining, and thyroarytenoid (TA) muscle atrophy was evaluated by hematoxylin and eosin staining. Immunohistochemical stainings for acetylcholinesterase (AchE), anti-neurofilament (NF), and anti-S100 protein were also conducted, and transmission electron microscopy (TEM) was used to evaluate functional nerve regeneration.
  
  
  RESULTS
  At eight weeks postoperatively, endoscopic evaluations showed significantly better recovery from VCP in the asymmetrically porous PCL/F127 NGC group (6 of 10 rabbits) than in the silicone tube group (1 of 10 rabbits). Continued nerve growth on the damaged nerve endings was observed with time in the asymmetrically porous PCL/F127 NGC-interposed RLNs. TA muscle dimensions and AchE expressions in TA muscle were significantly greater in the asymmetrically porous PCL/F127 NGC group than in the silicone tube group. Furthermore, immunohistochemical staining revealed the expression of NF and S100 protein in the regenerated nerves in the asymmetrically porous PCL/F127 NGC group at eight weeks postoperatively, and at this time, TEM imaging showed myelinated axons in the regenerated RLNs.
  
  
  CONCLUSIONS
  The study shows that asymmetrically porous PCL/F127 NGC provides a favorable environment for RLN regeneration and that it has therapeutic potential for the regeneration of RLN damage.
authors.affiliation: 1 Department of Otorhinolaryngology-Head and Neck Surgery, Inha University School of Medicine , Incheon, Republic of Korea.
authors.forename: Jeong-Seok
authors.initials: JS
authors.lastname: Choi
authors.forename: Se Heang
authors.initials: SH
authors.lastname: Oh
authors.forename: Hye-Young
authors.initials: HY
authors.lastname: An
authors.forename: Young-Mo
authors.initials: YM
authors.lastname: Kim
authors.forename: Jin Ho
authors.initials: JH
authors.lastname: Lee
authors.forename: Jae-Yol
authors.initials: JY
authors.lastname: Lim
mesh_terms: D000818:Animals; D001672:Biocompatible Materials; D005260:Female; D007821:Laryngeal Muscles / Q000098:blood supply / Q000473:pathology; D009133:Muscular Atrophy / Q000209:etiology; D009416:Nerve Regeneration / Q000502:physiology*; D016062:Porosity; D019736:Prostheses and Implants; D011817:Rabbits; D012009:Recurrent Laryngeal Nerve / Q000502:physiology / Q000601:surgery / Q000648:ultrastructure; D061226:Recurrent Laryngeal Nerve Injuries / Q000150:complications / Q000628:therapy*; D013965:Thyroidectomy / Q000009:adverse effects; D014826:Vocal Cord Paralysis / Q000517:prevention & control* / Q000601:surgery
chemical_list: D001672:Biocompatible Materials