Intraoperative Neuromonitoring During Thyroid Surgery: The Effect of Surgical Positioning

Surg Innov. 2019 Feb;26(1):77-81. doi: 10.1177/1553350618799786. Epub 2018 Sep 10.


Intraoperative neuromonitoring during thyroid surgery has been used to successfully prevent permanent neurological injury by early identification of anatomical variants. Proper interpretation of neuromonitoring data requires knowledge of what factors might affect the data. In this study, we examined the effect of surgical positioning on the latency and amplitude of neural recordings made from the vocalis muscle during thyroid surgery. A retrospective review was performed of 145 patients who underwent thyroid surgery. Eighty-three had open cervical procedures, and 62 had robotic-assisted transaxillary procedures. Intraoperative neuromonitoring recordings were made by stimulation of the vagus and recurrent laryngeal nerves for both groups. Ultrasound measurements were made of a subset of the transaxillary patients immediately before and after arm positioning. Groups differed only on right-sided recordings. Patients with transaxillary surgeries had significantly shorter latencies evoked from the vagus nerve. We found that vagus nerve-evoked latencies were also correlated to ultrasound measurements of the nerves. Surgical positioning during thyroid surgery is a factor that may affect intraoperative neuromonitoring data and should be taken into account by the surgeon during interpretation.

Keywords: endocrine surgery; evidence-based medicine/surgery; robotic surgery.

MeSH terms

  • Adult
  • Aged
  • Cohort Studies
  • Databases, Factual
  • Electromyography / methods
  • Female
  • Follow-Up Studies
  • Hospitals, University
  • Humans
  • Intraoperative Complications / prevention & control*
  • Male
  • Middle Aged
  • Monitoring, Intraoperative / methods
  • Neuronavigation*
  • Patient Positioning / methods*
  • Recurrent Laryngeal Nerve Injuries / diagnostic imaging
  • Recurrent Laryngeal Nerve Injuries / etiology
  • Recurrent Laryngeal Nerve Injuries / prevention & control*
  • Retrospective Studies
  • Risk Assessment
  • Robotic Surgical Procedures / adverse effects*
  • Robotic Surgical Procedures / methods
  • Thyroid Gland / pathology
  • Thyroid Gland / surgery
  • Thyroidectomy / adverse effects*
  • Thyroidectomy / methods
  • Time Factors
  • Treatment Outcome