Preoperative computed tomography diagnosis of non-recurrent inferior laryngeal nerve

The non-recurrent inferior laryngeal nerve (NRILN) is a nerve anomaly that is associated with the developmentally aberrant subclavian artery. Thus, it is possible to predict NRILN by preoperative diagnosis of an aberrant subclavian artery. Preoperative recognition of the NRILN should be advantageous in the prevention of intraoperative nerve damage. The purpose of this study was to assess the possibility of diagnosis of an aberrant subclavian artery by computed tomography (CT) of the neck, which is often performed before thyroid surgery.

We retrospectively studied the preoperative CT films from 594 thyroid or esophageal surgery patients treated in our hospital between May 1995 and December 2000. An NRILN was identified intraoperatively in 6 of these patients, and a right recurrent inferior laryngeal nerve (RILN) was observed in 588 of these patients. We evaluated whether the brachiocephalic artery could be identified on the CT scan and classified the positional relationship between the right subclavian artery and the tracheoesophagus into three types.

The brachiocephalic artery was identified on the CT films in 158 cases, all of which were cases of RILN. The right subclavian artery was detected on the ventral side of the membranous wall of the trachea in all 588 RILN cases, whereas it was detected on the dorsal side in all 6 NRILN cases.

It was possible to predict an aberrant subclavian artery by identifying the brachiocephalic artery and position of the right subclavian artery on the CT film of the neck. When an anomaly of the subclavian artery is thus preoperatively detected, NRILN can be preoperatively predicted, which likely will enable prevention of vocal cord paralysis.