Table 2. Causes and solutions of common IONM errors.

Common IONM errors	Causes	Solutions
Electrode impedance is too high	The subcutaneous electrodes have not completely removed after its withdrawal from patients	Check whether the subcutaneous electrodes fall off and keep the electrode clean
Subcutaneous electrodes >10 kΩ	The impedance of the electrode itself is too high	Replace the electrodes and fix them with tape
Stimulator probe electrodes >25 kΩ	The electrode core does not connect well with the interface-connector box	Check the connections of the interface-connector box
	The interface-connector box does not connect well with the monitor
Recording electrodes	The recording electrode does not connect well with vocal cord	Adjust the tube depth and angle under fiberoptic laryngoscope
Single electrode impedance >5 kΩ	The surface electrode of endotracheal tube is displaced	Indwell the tube under conventional video laryngoscope
Impedance deviation>1 kΩ	Application of insulating lubricant before intubation	Avoid the application of insulating medium at the recording electrodes
Electrode impedance is zero	Two subcutaneous electrodes contact with each other	Re-indwell the subcutaneous electrodes, with the inter-electrode distance of >1 cm
Electrosurgical interference	The probe of anti-jamming detector is not connected	Circle the cable of the electrosurgical device, with the anti-jamming detector clipped on the twisted cable
After the establishment of standard monitoring system	Preoperative vocal cord palsy	Re-check the preoperative laryngoscopic records
Before thyroid surgery	The nerve detected by the operator is actually not a vagus nerve	Detect at 1 mA after confirming the exposure of vagus nerve
V1 signal is absent	The vagus nerve is injured during its exposure	Directly detect the carotid sheath at 3 mA to obtain the V1 signal
	non-recurrent laryngeal nerve is present	If the signal of vagus nerve is absent at the plexas thyreoidea inferior level, re-check it at the plexas thyreoidea superior level
	Anesthesia induction is not performed as recommended	Wail until the muscle relaxant wears off or use a proper dose of a muscle relaxant antagonist
	Improper type or dosage of muscle relaxant	Check the matching between the measured stimulation (as displayed on monitor) and the stimulation setup value
	The detection current is not high enough	Re-check the connections between the electrodes and the interface-connector box
		Check whether the fuse in the interface-connector box has been burned out
	The frequency of stimulus pulse is too low	Stimulus pulse frequency: 4 times/s by default
	The setup of event threshold is too high	Routinely 100 μV; avoid changing this parameter value casually
	The selected monitoring mode, channel, and volume are improper	Re-check the monitoring mode, channel, and volume setup
	The duration of detection for nerve is too short	Each detection should be maintained at least 1s
	The probe is damaged, with insulation layer falling off	Avoid reuse
	The shunt of the nerve detection area is too large	Clear liquids at the detection area
	The muscle for detecting neurological effects is detached from the recording electrode	Re-check whether the electrodes are off
		The depth of the surface electrodes of endotracheal tube can be detected and located at the laryngeal anteromedian line
EMG signal is present while no nerve is detected	Consecutive “sequence” EMG response cannot be explained	Light anesthesia, with spontaneous activity of laryngeal muscle;
	Artifacts occur in the non-neural traveling area	the recording nerve or muscle is tracted by other nerve or muscle
	The detection current is too large	The surface electrode of endotracheal tube is placed too deeply
		Direct detect the nerve trunk (1 mA is recommended)
		Adjust according to the anatomic structures and EMG signals during the surgery
V1 signal is good, confirming the establishment of standard monitoring system, whereas there is the decrease of signal by >50% or LOS during the dissection of RLN	Intraoperative anesthesia or muscle relaxation status changes	Avoid adding muscle relaxant before the termination of monitoring
	Nerve transection injury	Check the nerve continuity
	Nerve injury not visible to the naked eye	Locate the injury site and analyze the possible injury mechanisms: traction injury, heat injury, suction injury, and/or thread-cutting injury
	Monitoring system failure	Re-check the electrode connections to ensure a good circuit performance
	Recording electrode displacement due to changes in head position or body position during the surgery	Use simulators to re-check the monitor and interface-connector box (e.g., fuse)
		Re-check the laryngoscope and adjust the endotracheal tube

RLN, recurrent laryngeal nerve.