Recurrent and superior laryngeal nerves: a new look with implications for the esophageal surgeon

Injury to the recurrent laryngeal nerve (RLN) is an unwelcome and not infrequent complication of operations on or near the upper thoracic or cervical esophagus. Because anatomic information useful to the surgeon is difficult to come by, the aim of this study was to reinvestigate and display the RLNs and superior laryngeal nerves in humans.

Postmortem en bloc specimens were studied: 23 by macroscopic dissection and 11 by large field serial histology. The nerves and their branches and supply areas were photographed at each step of dissection from the lateral (the surgeon's approach) and from the posterior aspect.

The RLNs were 2- to 3-mm thick compact slack cords, sinuously passing upward within the lateral peritracheal, and less frequent periesophageal, loose connective tissue, the left RLN being closer to the tracheoesophageal groove than the right. Both RLNs gave off 8 to 14 branches, equally distributed to the esophagus and trachea. These were 2.5- to 1-cm long when stretched. The primarily identical pattern became unpredictable underneath the thyroid gland, an area that covered approximately 3 cm of the proximal esophagus. The RLN, still fairly robust (>1 mm) dipped, being firmly attached, into the larynx laterocaudad to the cricopharyngeus muscle. As the RLN and superior laryngeal nerves supply the same laryngeal muscles and mucosa, this twofold innervation may compensate for some sequelae of RLN injury.

Displaying the RLNs, an important step in a variety of neck operations, dissection of the RLNs branches close to the esophagus and intestinocervical anastomosis as low as possible, will certainly reduce RLN injury.