- RLN is based on recording of evoked potentials via EMG at the vocalis muscle:
- Relies on a functioning neuromuscular junction
- Cannot be performed if neuromuscular blockers are administered
- EMG monitoring involves the use of 2 separate circuits – a stimulating and recording circuit
- A stimulating probe is used to generate an action potential in the RNL:
- Results in activation of the vocalis muscle and movement of the vocal cords
- A specialist Nerve Integrity Monitor (NIM) tube is used to record EMG signal at the level of the vocal cords:
- Has paired electrodes designed to contact the vocal folds
- Detects EMG activity which is converted in the monitor to audio and visual alerts
