title: Compound Motor Action Potential Quantifies Recurrent Laryngeal Nerve Innervation in a Canine Model.
abstract: OBJECTIVE
  The compound motor action potential (CMAP) is the summated action potential from multiple muscle fibers activated by a single nerve impulse. The utility of laryngeal muscle CMAP for quantifying innervation following recurrent laryngeal nerve (RLN) injury was investigated.
  
  
  METHODS
  In a series of 21 canine hemi-laryngeal preparations, RLNs were exposed and a stimulating electrode placed. Maximum CMAP amplitudes and area under the curve from the thyroarytenoid (TA) muscles were obtained at baseline and at 6 months following injury to the RLN. Injury mechanisms included crush, stretch, cautery, and complete transection with microsuture repair.
  
  
  RESULTS
  Prior to injury, baseline CMAP amplitudes and area under the curve were 15.81 mV and 15.49mVms, respectively. Six months following injury, CMAP amplitude and area under curve were 105.1% and 102.1% of baseline for stretch, 98.7% and 112.7% for crush, 93.3% and 114.3% for cautery. The CMAP amplitude and area under the curve in the transection/repair group had a 54.3% and 69.4% recovery, respectively, which were significantly different than baseline (P < .01, P < .05). These values were correlated with vocal fold motion.
  
  
  CONCLUSIONS
  The CMAP is a measure of vocal fold innervation. The technique could be further developed for clinical and experimental applications.
authors.affiliation: Department of Otolaryngology - Head and Neck Surgery, Washington University, Saint Louis, MO, USA bhattn@ent.wustl.edu.
authors.forename: Neel K
authors.initials: NK
authors.lastname: Bhatt
authors.affiliation: Department of Otolaryngology - Head and Neck Surgery, Washington University, Saint Louis, MO, USA.
authors.forename: Andrea M
authors.initials: AM
authors.lastname: Park
authors.affiliation: Department of Neurology, Washington University, Saint Louis, MO, USA.
authors.forename: Muhammad
authors.initials: M
authors.lastname: Al-Lozi
authors.affiliation: Department of Otolaryngology - Head and Neck Surgery, Washington University, Saint Louis, MO, USA.
authors.forename: Randal C
authors.initials: RC
authors.lastname: Paniello
mesh_terms: D000200:Action Potentials / Q000502:physiology*; D000818:Animals; D019540:Area Under Curve; D000071576:Crush Injuries; D004285:Dogs; D004576:Electromyography; D019054:Evoked Potentials, Motor / Q000502:physiology*; D007821:Laryngeal Muscles / Q000294:innervation*; D012009:Recurrent Laryngeal Nerve / Q000502:physiology* / Q000601:surgery; D061226:Recurrent Laryngeal Nerve Injuries / Q000503:physiopathology* / Q000601:surgery; D014827:Vocal Cords / Q000294:innervation*
keywords: larynx; surgical management; vagus nerve injury; vocal cord movement; vocal fold paralysis