title: [The influence of denervation on myofiber morphology of the adductor and abductor in patients with recurrent laryngeal nerve paralysis].
abstract: OBJECTIVE
  To investigate the influence of denervation on myofiber morphology of the adductor and the abductor in patients with recurrent laryngeal nerve (RLN) paralysis and to provide experimental evidence for the clinical feasibility of RLN repair.
  
  
  METHODS
  Adductor muscles were acquired from the lateral cricoarytenoid muscle (LCAM) and abductor muscles from the posterior cricoarytenoid muscle(PCAM). Normal human PCAM and LCAM are treated as control group (n = 7). Thirty-eight cases of PCAM with damaged RLN were divided into five groups according to the duration of their RLN damage: 0.5-1 year (7 cases), > 1-2 years (10 cases), > 2-3 years (8 cases), > 3-6 years (8 cases) and > 6 years (5 cases); twenty-nine cases of LCAM were also divided into five groups: 0.5-1 year (7 cases), > 1-2 years (6 cases); > 2-3 years (6 cases), > 3-6 years (6 cases) and > 6 years group(4 cases). They were all stained with HE and Masson three-color staining, the fiber cross-sectional area of muscle tissue and collagen connective tissue were quantitative analyzed. The changes of myofiber morphology of adductor and abductor muscles after the loss of the RLN were analyzed with image analysis system.
  
  
  RESULTS
  The transverse areas of myofibers gradually decreased and those of collagen fibers gradually increased with the prolongation of denervation. (1) Difference between the denervated groups of LCAM of 0.5-1 year, > 1-2 years and > 2-3 years groups were not significant (P > 0.05). Fiber cross-sectional area of > 3-6 years group decreased most obviously with significantly difference compared with > 2-3 years group (P < 0.05); (2) There were obvious difference between the control group, 0.5-1 year group, > 1-2 years group, > 2-3 years group and > 3-6 years of PCAM(P < 0.05); (3) There was no significant difference between the group of > 3-6 years and > 6 years of two kinds of laryngeal intrinsic muscle (P > 0.05); (4) Fiber cross-sectional area of each group of the LCAM after 1 year denervation were significantly greater than that of the PCAM under same conditions (P < 0.05).
  
  
  CONCLUSIONS
  The influence of denervation on myofiber morphology following denervation is different between the abductor and adductor owing to the different fiber type composition and functional properties. The rate of muscle atrophy of the adductor is slower than that of the abductor. To restore the structure and function of denervated laryngeal muscles better, the recurrent laryngeal nerve injury repair surgery for PCA muscle function recovery should be carried out within 1 year after denervation while the surgery for LCA muscle function recovery should be carried out within 3 years after denervation.
authors.affiliation: Department of Otolaryngology-Head and Neck Surgery, Changhai Hospital, the Second Military Medical University, Shanghai, 200433, China.
authors.forename: Xiaoxia
authors.initials: X
authors.lastname: Qiu
authors.forename: Hongliang
authors.initials: H
authors.lastname: Zheng
authors.forename: Shicai
authors.initials: S
authors.lastname: Chen
authors.forename: Donghui
authors.initials: D
authors.lastname: Chen
authors.forename: Jianqiu
authors.initials: J
authors.lastname: Chen
authors.forename: Wei
authors.initials: W
authors.lastname: Wang
authors.forename: Siwen
authors.initials: S
authors.lastname: Xia
mesh_terms: D016022:Case-Control Studies; D003714:Denervation; D006801:Humans; D007821:Laryngeal Muscles / Q000294:innervation / Q000473:pathology*; D009210:Myofibrils / Q000473:pathology*; D019635:Neurosurgical Procedures; D012009:Recurrent Laryngeal Nerve / Q000473:pathology*; D013194:Staining and Labeling; D014826:Vocal Cord Paralysis / Q000473:pathology* / Q000601:surgery