Duplex ultrasound and magnetic resonance imaging of the supra-aortic arches in patients with non recurrent inferior laryngeal nerve: a comparative study.

BACKGROUND Non-recurrent inferior laryngeal nerve (NRILN) is usually discovered during thyroid surgery. It is often associated with vascular abnormalities that can be detected with magnetic resonance imaging (MRI) or duplex ultrasound scan. The aim of this study was to compare the diagnostic sensitivity of ultrasonography with MRI to identify the vascular abnormalities associated to NRILN. PATIENTS AND METHODS We revised 2713 total thyroidectomies to select patients with NRILN. The NRILN was identified in 17 patients (0,6%). A postoperative ultrasonic duplex scanning and a MRI was performed in 15 cases as 2 patients refused to submit to the exams. RESULTS At MRI an unique origin of common carotid trunk and a concomitant aberrant retroesophageal subclavian right artery was showed in 11 patients. In 2 cases vascular abnormality consisted in separated origin of supra-aortic arteries. At duplex ultrasound scan only in 2 patients was impossible to identify vascular abnormalities detected at MRI. Tthe diagnostic sensitivity of duplex ultrasound was 84,6%. CONCLUSIONS Preoperative duplex ultrasound is a non invasive method with high diagnostic sensitivity that can easily complete the preoperative thyroid ultrasonography.