title: Laryngeal adductor function in experimental models of recurrent laryngeal nerve injury.
abstract: OBJECTIVE
  Most patients with unilateral vocal fold paralysis experience some degree of spontaneous reinnervation, which depends upon the type and severity of recurrent laryngeal nerve (RLN) injury. After partial recovery, the paretic vocal fold may or may not adduct adequately to allow glottic closure, which in turn affects phonatory and swallowing outcomes. This process was studied in a series of canine laryngeal nerve injury models.
  
  
  METHODS
  Animal (canine) experiments.
  
  
  METHODS
  Maximum stimulable laryngeal adductor pressure (LAP) was measured pretreatment (baseline) and at 6 months following experimental RLN injuries (total n = 59). The nine study groups were designed to simulate a range of severities of RLN injury.
  
  
  RESULTS
  The greatest LAP recovery, at 108% of original baseline, was seen in a 50% transection model; the least recovery was seen when the RLN underwent complete transection with repair, at 56% with precise alignment and 50% with alignment reversed. Intermediate models (partial RLN injuries) gave intermediate results. Crush models recovered 105% of LAP, whereas a half-transection, half-crush injury recovered 72%, and cautery injuries recovered 61%. Controls (complete transection without repair) had no measurable recovery.
  
  
  CONCLUSIONS
  The injured RLN has a strong tendency to recover. Restoration of adductor strength, as determined by the LAP, was predictably related to the severity of RLN injury. The model RLN injuries studied provide a range of expected outcomes that can be used for future experiments exploring interventions that may improve postinjury adductor function.
  
  
  METHODS
  NA.
authors.affiliation: Department of Otolaryngology-Head and Neck Surgery, Washington University, St. Louis, Missouri, U.S.A; the St. Louis Veterans Affairs Medical Center, St. Louis, Missouri, U.S.A.
authors.forename: Randal C
authors.initials: RC
authors.lastname: Paniello
authors.forename: Jason T
authors.initials: JT
authors.lastname: Rich
authors.forename: Nick L
authors.initials: NL
authors.lastname: Debnath
mesh_terms: D000818:Animals; D004195:Disease Models, Animal; D004285:Dogs; D005260:Female; D007821:Laryngeal Muscles / Q000294:innervation*; D020127:Recovery of Function; D061226:Recurrent Laryngeal Nerve Injuries / Q000503:physiopathology*
keywords: Vocal cord; canine; paralysis; reinnervation; synkinesis