Nerve at risk: anatomical variations of the left recurrent laryngeal nerve and implications for thoracic surgeons

Recurrent laryngeal nerve (RLN) injury during thoracic surgery may result in life-threatening postoperative complications including recurrent aspiration and pneumonia. Anatomical details of the intrathoracic course are scarce. However, only an in-depth understanding of the anatomy will help reduce nerve injury. The aim of this study was to assess the anatomic variations of the intrathoracic left RLN.

Left-sided vagal nerves and RLN were dissected in 100 consecutive Caucasian cadavers during routine autopsy. Anatomical details were documented. Available demographic data were assessed for possible correlations.

All nerves were identified during dissection. Variant courses were classified in 3 different groups according to the level at which the RLN separated from the vagal nerve: above the aortic arch, level with the aortic arch and below the aortic arch. We found 11% of RLN separating above the aortic arch and crossing the aortic arch at a considerable distance to the vagal nerve. In 48% of the RLN, the nerve split off when it was level with the aortic arch, and 41% of the RLN leave the vagal nerve in a perpendicular direction below the aortic arch. All nerves crossed the ligamentum arteriosum on the posterior side. No gender-specific differences were observed.

Mediastinal lymph node dissection in left-sided lung cancer patients puts the RLN at risk. With more detailed anatomical knowledge about its course, it is possible to avoid risking the nerve. Visualization will help protect the nerve.