Table 4. The power of laryngeal examination and neural monitoring for causal link evidence. The standards of RLN management include extensive knowledge of RLN anatomy, visual identification and functional confirmation of RLN (neural monitoring), nerve exposure, training and certainly pre- and postoperative laryngeal examination (L1 and L2, respectively). Only the association between laryngoscopy and neuromonitoring can confirm the causal link between RLN injury and surgery.

No.	Causal link
1	L1 negative, normal vocal cord movement
2	Pre-dissection/baseline vagal nerve stimulation (V1) and RLN (R1) normal*,**
2	Loss of EMG signal or reduced EMG signal (<100 mcV) during thyroid surgery^
3	Intraoperative suspect of RLN palsy
4	Loss of EMG signal or reduced EMG signal end surgery (V2 and R2)^
5	L2 positive for RLN palsy/paralysis, vocal cord impairment

EMG, electromyography; RLN, recurrent laryngeal nerve; L1, preoperative laryngeal examination; L2, postoperative laryngeal examination; V1, pre-dissection stimulation of vagal nerve; R1, pre-dissection stimulation of RLN; V2, post-dissection stimulation of vagal nerve; R2, post-dissection stimulation of RLN. *Definition of normal EMG signal (functionally intact RLN): EMG biphasic waveform, satisfactory amplitude (>200 mcV) and latency. **If L1 negative, but V1 and R1 EMG signals absent, hypothesize vocal cord injury due to intubation. L2 will demonstrate edema, hematoma, or direct injury to the vocal cord. ^Definition of loss of EMG signal: (a) normal vocal cord movement at L1, (b) initial EMG satisfactory, (c) no EMG response with stimulation at 1–2 mA, (d) low response <100 mcV with stimulation at 1–2 mA, (e) no laryngeal twice, (f) neural monitoring trouble shooting algorithm applied systematically.