title: Identification of the non-recurrent inferior laryngeal nerve using intraoperative neurostimulation.
abstract: BACKGROUND
  The non-recurrent inferior laryngeal nerve occurs at a frequency of about 0.5% and usually on the right side. The identification of a non-recurrent laryngeal nerve may be difficult. We describe a new method for its identification using intraoperative neurostimulation.
  
  
  METHODS
  We examined nine patients with a non-recurrent inferior laryngeal nerve and five patients with a normal inferior laryngeal nerve anatomy who were operated on trans-sternally. Neurostimulation of the vagal nerve producing electromyographic signal in the intrinsic laryngeal musculature was performed at different points proximally and distally.
  
  
  RESULTS
  : Electromyographic signals were found proximally but not distally of the separation of the inferior laryngeal nerve from the vagus in 14 patients. In nine patients with a non-recurrent inferior laryngeal nerve, we performed neurostimulation of the vagus opposite the lower and the upper thyroid poles. In all patients we found no electromyographic signals at the distal stimulation point. In contrast, proximal neurostimulation of the vagus opposite the upper thyroid pole produced positive electromyographic signals.
  
  
  CONCLUSIONS
  Neurostimulation of the vagal nerve distally of the separation of the inferior laryngeal nerve did not produce electromyographic signals in the intrinsic laryngeal musculature, perhaps due to the different modalities in the vagal fascicles. Negative electromyographic signals following neurostimulation of the distal vagal nerve opposite the lower thyroid pole should lead to proximal neurostimulation of the vagus opposite the upper thyroid pole. Positive electromyographic signals proximally and negative electromyographic signals distally predict the occurrence of a non-recurrent inferior laryngeal nerve which allows its diagnosis before surgical dissection of the thyroid gland and may prevent nerve palsy.
authors.affiliation: Klinik für Allgemeinchirurgie, Martin-Luther-Universität Halle-Wittenberg, Ernst-Grube-Strasse 40, 06097 Halle/Saale, Germany. michael.brauckhoff@medizin.uni-halle.de
authors.forename: Michael
authors.initials: M
authors.lastname: Brauckhoff
authors.forename: Gerard
authors.initials: G
authors.lastname: Walls
authors.forename: Katrin
authors.initials: K
authors.lastname: Brauckhoff
authors.forename: Phuong Nguyen
authors.initials: PN
authors.lastname: Thanh
authors.forename: Oliver
authors.initials: O
authors.lastname: Thomusch
authors.forename: Henning
authors.initials: H
authors.lastname: Dralle
mesh_terms: D000328:Adult; D000368:Aged; D018276:Carcinoma, Medullary / Q000473:pathology / Q000503:physiopathology / Q000601:surgery*; D004558:Electric Stimulation / Q000379:methods*; D004576:Electromyography; D005260:Female; D006045:Goiter, Substernal / Q000473:pathology / Q000503:physiopathology / Q000601:surgery*; D006801:Humans; D007430:Intraoperative Care / Q000379:methods*; D008297:Male; D008875:Middle Aged; D012009:Recurrent Laryngeal Nerve / Q000473:pathology* / Q000503:physiopathology*; D013964:Thyroid Neoplasms / Q000473:pathology / Q000503:physiopathology / Q000601:surgery*; D014630:Vagus Nerve / Q000473:pathology / Q000503:physiopathology