title: Evoked electromyographic technique for quantitative assessment of the innervation status of laryngeal muscles.
abstract: OBJECTIVE
  The purpose of this study was to develop a minimally invasive, noninjurious evoked electromyographic technique that could accurately quantitate the level of innervation of laryngeal muscles with recurrent laryngeal nerve stimulation.
  
  
  METHODS
  A four-phase study was conducted in 24 canines, including 1) identification of the best stimulation-recording configuration, 2) statistical analysis of sensitivity and accuracy, 3) evaluation of safety, and 4) identification of the laryngeal muscle(s) that contribute to the evoked response.
  
  
  RESULTS
  The results demonstrated that an entirely noninvasive technique is not feasible. The stimulating cathode must be invasive to ensure discrete activation of the recurrent laryngeal nerve, whereas both recording electrodes should remain on the surface with one overlying the thyroid ala. This configuration proved to be highly accurate, with an error rate of only 6% to 7%, and with sensitivity sufficient to detect a signal in a nerve with fewer than 1% of the axons intact. There was no evidence of nerve injury in any animal over the course of 350 stimulus needle penetrations. By use of neuromuscular blockade to identify those muscles generating the surface response, the thyroarytenoid muscle was found to be the primary contributor, whereas the posterior cricoarytenoid muscle was uninvolved.
  
  
  CONCLUSIONS
  This evoked electromyographic technique could provide quantitative information regarding the extent of muscle innervation during denervation and regeneration in case of laryngeal paralysis.
authors.affiliation: Department of Otolaryngology-Head and Neck Surgery, Vanderbilt University Medical School, Nashville, Tennessee, USA.
authors.forename: David L
authors.initials: DL
authors.lastname: Zealear
authors.forename: Matthew R
authors.initials: MR
authors.lastname: Swelstad
authors.forename: Scott
authors.initials: S
authors.lastname: Fortune
authors.forename: Ricardo J
authors.initials: RJ
authors.lastname: Rodriguez
authors.forename: Sung-Min
authors.initials: SM
authors.lastname: Chung
authors.forename: Klara
authors.initials: K
authors.lastname: Valyi-Nagy
authors.forename: Mark J
authors.initials: MJ
authors.lastname: Billante
authors.forename: Cheryl R
authors.initials: CR
authors.lastname: Billante
authors.forename: Kurt
authors.initials: K
authors.lastname: Garren
mesh_terms: D000818:Animals; D004285:Dogs; D004576:Electromyography / Q000379:methods*; D005071:Evoked Potentials; D007821:Laryngeal Muscles / Q000294:innervation*; D012038:Regeneration; D012680:Sensitivity and Specificity