The nonrecurrent laryngeal nerve: anatomic and electrophysiologic algorithm for reliable identification

Area of Science:

• Neurosurgery
• Otolaryngology
• Thyroid Surgery

Background:

• The recurrent laryngeal nerve (RLN) is crucial for vocal cord function during thyroid surgery.
• Intraoperative monitoring (IONM) aids in RLN identification and management.
• The nonrecurrent laryngeal nerve (NRLN) presents a unique challenge due to its aberrant anatomy and increased risk of injury.

Purpose of the Study:

• To apply IONM for identifying the nonrecurrent laryngeal nerve (NRLN).
• To establish electrophysiologic and anatomic parameters for reliable NRLN identification.
• To develop an algorithm to prevent NRLN injury during thyroid surgery.

Main Methods:

• Retrospective study of thyroid surgeries utilizing IONM.
• Analysis of cases involving the nonrecurrent laryngeal nerve (NRLN).
• Preoperative and postoperative laryngoscopy documented for all cases; electrophysiologic parameters compared to normal nerves.

Main Results:

• The nonrecurrent laryngeal nerve (NRLN) was identified in 0.6% of cases (10 right-sided nerves).
• All identified NRLNs maintained normal laryngeal function postoperatively.
• Electrophysiologic parameters for NRLN identification were established using distal and proximal vagal nerve stimulation.

Conclusions:

• The nonrecurrent laryngeal nerve (NRLN) occurs in 0.6% of thyroid surgery patients.
• IONM with vagal stimulation reliably verifies NRLN presence intraoperatively.
• Anatomic subtypes and an electrophysiologic algorithm aid in early NRLN identification and injury prevention.