title: Effect of laryngotracheal topical anesthesia on recurrent laryngeal nerve monitoring during thyroid Surgery.
abstract: OBJECTIVE
  Intraoperative neuromonitoring of the recurrent laryngeal nerve (RLN) is often used as an adjunct for RLN identification and preservation during thyroidectomies. Laryngotracheal anesthesia (LTA) with topical lidocaine reduces coughing upon emergence from anesthesia and in the immediate postoperative period; however, its use is prohibited with concerns that it could decrease the sensitivity of the intraoperative neuromonitoring. We hypothesize that there is no difference in measurements of nerve conduction made before and after LTA administration.
  
  
  METHODS
  An observational study in which all patients were subjected to LTA administration was conducted. Recurrent laryngeal nerve threshold currents were measured before and after the intervention.
  
  
  METHODS
  Tertiary medical center operating room.
  
  
  METHODS
  Eighteen patients (total of 25 nerves at risk) with American Society of Anesthesiologists classes 1 to 3 undergoing thyroid surgery.
  
  
  METHODS
  After the thyroid was removed and threshold currents at the RLN were obtained, LTA with endotracheal lidocaine was applied on the left and right side of the in situ endotracheal tube (2 cc of 4% lidocaine per side). Threshold currents were reassessed at 5 and 10 minutes after LTA administration.
  
  
  METHODS
  Threshold currents (minimum stimulus current applied to the RLN required to generate a discernible electromyographic response at the vocal cords) were recorded along the RLN for a baseline at 5 and 10 mm from the insertion point of the RLN into the larynx. Threshold currents were reassessed at the same 2 positions on the RLN at 5 and 10 minutes after LTA administration. Differences in mean values, between threshold currents recorded at the 3 different times, at 2 positions on the RLN, were used to compare effects of LTA on nerve conduction.
  
  
  RESULTS
  There were no statistically significant differences when comparing threshold currents before and after LTA administration.
  
  
  CONCLUSIONS
  Laryngotracheal anesthesia had no significant effect on RLN nerve conduction in the period assessed.
authors.affiliation: Department of Anesthesiology, Head and Neck Surgery, Penn State College of Medicine and Penn State Hershey Medical Center, Hershey, PA, USA. Electronic address: jpachuski1@hmc.psu.edu.
authors.forename: Justin
authors.initials: J
authors.lastname: Pachuski
authors.affiliation: Department of Anesthesiology, Head and Neck Surgery, Penn State College of Medicine and Penn State Hershey Medical Center, Hershey, PA, USA. Electronic address: svaida@hmc.psu.edu.
authors.forename: Sonia
authors.initials: S
authors.lastname: Vaida
authors.affiliation: Department of Anesthesiology, Head and Neck Surgery, Penn State College of Medicine and Penn State Hershey Medical Center, Hershey, PA, USA. Electronic address: kdonahue@hmc.psu.edu.
authors.forename: Kathleen
authors.initials: K
authors.lastname: Donahue
authors.affiliation: Department of Surgery, Division of Otolaryngology, Head and Neck Surgery, Penn State College of Medicine and Penn State Hershey Medical Center, Hershey, PA, USA. Electronic address: jroberts8@hmc.psu.edu.
authors.forename: John
authors.initials: J
authors.lastname: Roberts
authors.affiliation: Department of Public Health Sciences, Penn State College of Medicine, Hershey, PA, USA. Electronic address: ark3@psu.edu.
authors.forename: Allen
authors.initials: A
authors.lastname: Kunselman
authors.affiliation: Department of Surgery, Division of Otolaryngology, Head and Neck Surgery, Penn State College of Medicine and Penn State Hershey Medical Center, Hershey, PA, USA. Electronic address: boberman@hmc.psu.edu.
authors.forename: Benjamin
authors.initials: B
authors.lastname: Oberman
authors.affiliation: Department of Surgery, Division of Otolaryngology, Head and Neck Surgery, Penn State College of Medicine and Penn State Hershey Medical Center, Hershey, PA, USA. Electronic address: hpatel5@hmc.psu.edu.
authors.forename: Hetal
authors.initials: H
authors.lastname: Patel
authors.affiliation: Department of Surgery, Division of Otolaryngology, Head and Neck Surgery, Penn State College of Medicine and Penn State Hershey Medical Center, Hershey, PA, USA. Electronic address: dgoldenberg@hmc.psu.edu.
authors.forename: David
authors.initials: D
authors.lastname: Goldenberg
mesh_terms: D000779:Anesthetics, Local / Q000494:pharmacology*; D004558:Electric Stimulation / Q000379:methods; D004576:Electromyography / Q000187:drug effects; D006801:Humans; D007830:Larynx / Q000187:drug effects; D008012:Lidocaine / Q000494:pharmacology; D016343:Monitoring, Intraoperative / Q000379:methods*; D009431:Neural Conduction / Q000187:drug effects; D012009:Recurrent Laryngeal Nerve / Q000187:drug effects* / Q000502:physiology; D061226:Recurrent Laryngeal Nerve Injuries / Q000209:etiology / Q000517:prevention & control; D013965:Thyroidectomy / Q000009:adverse effects*; D014132:Trachea / Q000187:drug effects; D014827:Vocal Cords / Q000187:drug effects
chemical_list: D000779:Anesthetics, Local; D008012:Lidocaine
keywords: Intraoperative neuromonitoring; Laryngotracheal topical anesthesia; Lidocaine; Recurrent laryngeal nerve; Thyroidectomy