Intraoperative neuromonitoring (IONM) of the recurrent laryngeal nerve during thyroid surgery: which signal loss pattern mandates halting ipsilateral dissection immediately?
- A Loss of electromyographic (EMG) signal (type 2 signal loss) after a discrete event suggesting traction or thermal injury ✓
- B Loss of signal amplitude >50% from baseline with intact signal on contralateral side
- C Signal amplitude decrease of 20-30% during retraction of the thyroid lobe
- D Absence of baseline signal before dissection begins
Correct answer: A. Loss of electromyographic (EMG) signal (type 2 signal loss) after a discrete event suggesting traction or thermal injury
Explanation
Intraoperative neuromonitoring distinguishes type 1 loss (gradual, reversible, typically from traction) and type 2 loss (abrupt loss of EMG signal usually after an identifiable event such as energy device injury or ligature), which carries high risk for permanent RLN palsy. Type 2 signal loss mandates immediate cessation of ipsilateral dissection and reassessment. If the contralateral side has not been operated on, staged thyroidectomy is recommended to avoid bilateral cord paralysis and respiratory compromise.
Reference: Bailey & Love's Short Practice of Surgery, 27th ed.
High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP
Written and medically reviewed by the StethoPrep medical team.