Intraoperative identification of a left non-recurrent laryngeal nerve by neuromonitoring: a critical anatomical finding-case report.

Injury to the recurrent laryngeal nerve (RLN) and its non-recurrent variant (NRLN) remains one of the most significant complications of thyroid and parathyroid surgery. The NRLN is a rare anatomical variation that arises directly from the cervical vagus nerve without looping into the thoracic cavity, most often associated with an aberrant subclavian artery. Identification of this structure is essential to avoid iatrogenic injury, particularly during thyroidectomy. We report the intraoperative neuromonitoring (IONM) identification of an unexpected non-recurrent left inferior laryngeal nerve; emerging directly from the vagus nerve and coursing horizontally towards the larynx. This case emphasizes the importance of IONM, surgical awareness of anatomical variation to prevent RLN and NRLN injury, and ensuring optimal postoperative laryngeal function.