title: Electrophysiologic monitoring characteristics of the recurrent laryngeal nerve preoperatively paralyzed or invaded with malignancy.
abstract: OBJECTIVE
  To elucidate electrophysiologic responses of the recurrent laryngeal nerves that were preoperatively paralyzed or invaded by malignancy and to use this information as an added functional parameter for intraoperative management of recurrent laryngeal nerves with malignant invasion.
  
  
  METHODS
  Case series with chart review.
  
  
  METHODS
  Academic, tertiary care center.
  
  
  METHODS
  All consecutive neck surgeries with nerve monitoring performed by senior author (GWR) between December 1995 and January 2007 were reviewed after obtaining Institutional Review Board approval from Massachusetts Eye and Ear Infirmary Human Subjects Committee and the Partners Human Research Committee. Electrophysiologic parameters in all cases with preoperative vocal cord paralysis/paresis, and the recurrent laryngeal nerve invasion by cancer, were studied.
  
  
  RESULTS
  Of the 1138 surgeries performed, 25 patients (2.1%) had preoperative vocal cord dysfunction. In patients with preoperative vocal cord dysfunction, recognizable recurrent laryngeal nerve electrophysiologic activity was preserved in over 50% of cases. Malignant invasion of the recurrent laryngeal nerve was found in 22 patients (1.9%). Neural invasion of the recurrent laryngeal nerve was associated with preoperative vocal cord paralysis in only 50% of these patients. In nerves invaded by malignancy, 60% maintained recognizable electrophysiologic activity, which was more commonly present and robust when vocal cord function was preserved.
  
  
  CONCLUSIONS
  Knowledge of electrophysiologic intraoperative neural monitoring provides additional functional information and, along with preoperative vocal cord function information, aids in constructing decision algorithms regarding intraoperative management of the recurrent laryngeal nerve, in prognosticating postoperative outcomes, and in patient counseling regarding postoperative expectations.
authors.affiliation: Massachusetts Eye and Ear Infirmary, Division of Thyroid and Parathyroid Surgery, Harvard Medical School, Boston, Massachusetts, USA.
authors.forename: Dipti
authors.initials: D
authors.lastname: Kamani
authors.forename: E Ashlie
authors.initials: EA
authors.lastname: Darr
authors.forename: Gregory W
authors.initials: GW
authors.lastname: Randolph
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D003937:Diagnosis, Differential; D004576:Electromyography; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D008297:Male; D008875:Middle Aged; D008991:Monitoring, Physiologic / Q000379:methods*; D009361:Neoplasm Invasiveness; D057234:Preoperative Period; D011379:Prognosis; D012009:Recurrent Laryngeal Nerve / Q000473:pathology / Q000503:physiopathology*; D012189:Retrospective Studies; D013964:Thyroid Neoplasms / Q000150:complications* / Q000473:pathology / Q000601:surgery; D013965:Thyroidectomy; D014826:Vocal Cord Paralysis / Q000209:etiology / Q000473:pathology / Q000503:physiopathology*; D055815:Young Adult
keywords: EMG; IONM; electrophysiologic parameters; invasive malignancy; recurrent laryngeal nerve monitoring; surgery for thyroid cancer; thyroid malignancy; vocal cord paralysis