title: Impact of EMG Changes in Continuous Vagal Nerve Monitoring in High-Risk Endocrine Neck Surgery.
abstract: BACKGROUND
  Continuous vagal intraoperative neuromonitoring (CIONM) of the recurrent laryngeal nerve (RLN) may reduce the risk of RLN lesions during high-risk endocrine neck surgery such as operation for large goiter potentially requiring transsternal surgery, advanced thyroid cancer, and recurrence.
  
  
  METHODS
  Fifty-five consecutive patients (41 female, median age 61 years, 87 nerves at risk) underwent high-risk endocrine neck surgery. CIONM was performed using the commercially available NIM-Response 3.0 nerve monitoring system with automatic periodic stimulation (APS) and matching endotracheal tube electrodes (Medtronic Inc.). All CIONM events (decreased amplitude/increased latency) were recorded.
  
  
  RESULTS
  APS malfunction occurred on three sides (3%). A total of 138 CIONM events were registered on 61 sides. Of 138, 47 (34%) events were assessed as imminent (13 events) or potentially imminent (34 events) lesions, whereas 91 (66%) were classified as artifacts. Loss of signal was observed in seven patients. Actions to restore the CIONM baseline were undertaken in 58/138 (42%) events with a median 60 s required per action. Four RLN palsies (3 transient, 1 permanent) occurred: one in case of CIONM malfunction, two sudden without any significant previous CIONM event, and one without any CIONM event. The APS vagus electrode led to temporary damage to the vagus nerve in two patients.
  
  
  CONCLUSIONS
  CIONM may prevent RLN palsies by timely recognition of imminent nerve lesions. In high-risk endocrine neck surgery, CIONM may, however, be limited in its utility by system malfunction, direct harm to the vagus nerve, and particularly, inability to indicate RLN lesions ahead in time.
authors.affiliation: Department of Surgery, Haukeland University Hospital, Jonas Lies vei 65, 5021, Bergen, Norway. katrin.brauckhoff@helse-bergen.no.
authors.forename: Katrin
authors.initials: K
authors.lastname: Brauckhoff
authors.affiliation: Department of Surgery, Haukeland University Hospital, Jonas Lies vei 65, 5021, Bergen, Norway.
authors.forename: Renate
authors.initials: R
authors.lastname: Vik
authors.affiliation: Department of ENT, Haukeland University Hospital, Bergen, Norway.
authors.forename: Lorentz
authors.initials: L
authors.lastname: Sandvik
authors.affiliation: Department of ENT, Haukeland University Hospital, Bergen, Norway.|Department of Clinical Medicine, University of Bergen, Bergen, Norway.
authors.forename: John-Helge
authors.initials: JH
authors.lastname: Heimdal
authors.affiliation: Department of Surgery, Haukeland University Hospital, Jonas Lies vei 65, 5021, Bergen, Norway.
authors.forename: Turid
authors.initials: T
authors.lastname: Aas
authors.affiliation: Department of Clinical Medicine, University of Bergen, Bergen, Norway.|Department of Radiology, Haukeland University Hospital, Bergen, Norway.
authors.forename: Martin
authors.initials: M
authors.lastname: Biermann
authors.affiliation: Department of Surgery, Haukeland University Hospital, Jonas Lies vei 65, 5021, Bergen, Norway.|Department of Clinical Science, University of Bergen, Bergen, Norway.
authors.forename: Michael
authors.initials: M
authors.lastname: Brauckhoff
mesh_terms: D000328:Adult; D000368:Aged; 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 / Q000009:adverse effects; D011183:Postoperative Complications / Q000175:diagnosis / Q000517:prevention & control; D011446:Prospective Studies; D012009:Recurrent Laryngeal Nerve / Q000503:physiopathology*; D061226:Recurrent Laryngeal Nerve Injuries / Q000150:complications / Q000175:diagnosis* / Q000517:prevention & control; D012307:Risk Factors; D013959:Thyroid Diseases / Q000209:etiology; D013965:Thyroidectomy / Q000009:adverse effects*; D014630:Vagus Nerve / Q000503:physiopathology*; D014826:Vocal Cord Paralysis / Q000175:diagnosis / Q000209:etiology / Q000517:prevention & control*