Preoperative three-dimensional CT angiography to distinguish between an aberrant subclavian artery and a double aortic arch in thyroid surgery: Report of 2 cases.

A non-recurrent inferior laryngeal nerve (NRILN), a very rare anatomic variation, is easily damaged during thyroid surgery. Due to impairments during embryonic development, a NRILN is frequently associated with an aberrant subclavian artery. Thus, an aberrant subclavian artery is now regarded as an important vascular anomaly for predicting the presence of a NRILN using various imaging modalities. However, precise imaging is often necessary as other vascular anomalies, such as a double aortic arch, can cause difficulties in discriminating between an aberrant subclavian artery and other anatomic variations. For this reason, computed tomography (CT) is usually necessary before thyroid surgery. but, to take more precise images, newly developed techniques such as computed tomography angiography (CTA) are needed. To indentify NRILNs, we performed CTA preoperatively in two patients with thyroid cancer. CTA demonstrated an aberrant subclavian artery with an associated NRILN in one patient and a double aortic arch with a recurrent inferior laryngeal nerve (RILN) in the second patient. Thyroid surgery was successful, and the laryngeal nerve was preserved in both patients. Preoperative CTA is much safer and less time-consuming than catheter angiography. Also, CTA is a cost-effective three-dimensional imaging modality for identifying aberrant subclavian arteries associated with NRILNs, as compared with double aortic arches associated with RILNs.