title: Stimulation threshold greatly affects the predictive value of intraoperative nerve monitoring.
abstract: OBJECTIVE
  Using a standardized, graded, intraoperative stimulation protocol, we aimed to delineate the effects of various stimulation levels applied to the recurrent laryngeal nerve on the postoperative predictive value of intraoperative nerve monitoring.
  
  
  METHODS
  A total of 917 nerves at risk were included for analysis. Intraoperatively, patients underwent stimulation of the recurrent laryngeal nerve at 0.3, 0.5, 0.8, and 1.0 mA followed by postoperative laryngoscopy for correlation with intraoperative findings.
  
  
  METHODS
  Sensitivity, specificity, positive predictive value, and negative predictive value were calculated at each stimulation level.
  
  
  RESULTS
  Sensitivity, specificity, positive predictive value, and negative predicative values ranged from 100% to 37%, 6% to 99%, 2% to 39%, and 100% to 99%, respectively at 0.3 to 1.0 mA. No demographic variables affected sensitivity or specificity. Receiver operating characteristic analysis identified 0.5 mA as the level of stimulation that optimizes sensitivity and specificity.
  
  
  CONCLUSIONS
  The predictive value of intraoperative nerve monitoring varies greatly depending on the stimulation levels used. At low amplitudes of stimulation, nerve monitoring has high sensitivity and negative predictive value but low specificity and positive predictive value, related to the high rate of false positives. At high levels of stimulation, specificity and negative predictive value are high, sensitivity is low, and the positive predictive value rises as the rate of false negatives increase and the rate of false positives decrease. A stimulation level of 0.5 mA optimizes the predictive value of nerve monitoring; however, stimulation at multiple levels significantly improves the predictive value of intraoperative nerve monitoring.
  
  
  METHODS
  2b.
authors.affiliation: Department of Otolaryngology-Head and Neck Surgery , University of California, San Francisco, San Francisco, California; School of Medicine , University of California, San Francisco, San Francisco, California.
authors.forename: Daniel L
authors.initials: DL
authors.lastname: Faden
authors.forename: Lisa A
authors.initials: LA
authors.lastname: Orloff
authors.forename: Tokunbo
authors.initials: T
authors.lastname: Ayeni
authors.forename: Daniel S
authors.initials: DS
authors.lastname: Fink
authors.forename: Katherine
authors.initials: K
authors.lastname: Yung
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D004599:Electric Stimulation Therapy / Q000379:methods*; D004576:Electromyography / Q000379:methods*; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D008297:Male; D008875:Middle Aged; D016343:Monitoring, Intraoperative / Q000379:methods*; D037981:Neck Dissection; D011237:Predictive Value of Tests; D012372:ROC Curve; D012009:Recurrent Laryngeal Nerve / Q000502:physiology*; D061226:Recurrent Laryngeal Nerve Injuries / Q000503:physiopathology / Q000517:prevention & control*; D012189:Retrospective Studies; D012684:Sensory Thresholds / Q000502:physiology*; D055815:Young Adult
keywords: Recurrent laryngeal nerve; intraoperative nerve monitoring; thyroid surgery