Usefulness of intraoperative neuromonitoring for preservation of an extralaryngeal bifurcation of the recurrent laryngeal nerve: A case report

Introduction: Recurrent laryngeal nerve injury is a major complication of thyroid surgery. An endotracheal tube with electromyography electrodes attached to it was recently developed for intraoperative neuromonitoring during thyroid surgery. Here we describe the successful identification and preservation of an extralaryngeal bifurcation of the recurrent laryngeal nerve by intraoperative neuromonitoring in a patient undergoing thyroid surgery. Presentation of case: A 56-year-old woman presented for evaluation of a neck swelling found during a medical examination. Computed tomography (CT) revealed a tumor with a 5-cm diameter in the left thyroid lobe. Fine needle aspiration cytology revealed a Bethesda category III finding. Left thyroid lobe resection was scheduled. During surgery, the left recurrent laryngeal nerve was found to be adhered to the tumor. Careful exploration and intraoperative neuromonitoring allowed us to identify and preserve an extralaryngeal bifurcation of the recurrent laryngeal nerve. Discussion: The recurrent laryngeal nerve can demonstrate various anomalies and bifurcations. Failure to notice and correctly identify extralaryngeal bifurcation leads to recurrent laryngeal nerve injury. Motor branch injury has a particularly large effect. Intraoperative neuromonitoring has been reported to be useful for identifying and preserving the recurrent laryngeal nerve and its aberrations as well as the external branch of the superior laryngeal nerve during thyroid surgery. Conclusion: The findings from this case suggest that an extralaryngeal bifurcation of the recurrent laryngeal nerve can be identified and safely preserved by intraoperative neuromonitoring.