A persistent left superior vena cava, with the accessory nerve passing through a duplicate segment of the left internal jugular vein: a unique presentation.

The internal jugular vein and the spinal accessory nerve are important landmarks during neck dissection; unexpected variations in their positions can result in inadvertent iatrogenic damage to adjacent structures. We report the case of a 79-year-old man who was found during neck dissection to have a duplicate segment of his left internal jugular vein (IJV), a persistent left superior vena cava, and an absent right superior vena cava. The spinal accessory nerve passed through the duplicate section of the IJV. A MEDLINE search found no previously reported case of these anomalies occurring together. We also review 10 previously reported cases of IJV duplication. Finally, we discuss the embryologic and anatomic background of these malformations so that otolaryngologists may be aware that identification of such anomalies may help to prevent postoperative morbidity.