Identification and management of intravagal parathyroid adenoma.

Intravagal parathyroid adenomas are rare, with only three cases reported in the English literature. The objective of this report is to describe two additional patients with hyperfunctioning parathyroid glands found within the vagus nerve and to define the anatomy of this finding. Both patients presented with a history of persistent hyperparathyroidism despite multiple therapeutic interventions. A high cervical localization was established in both cases by selective venous sampling. In each patient successful removal of the intravagal parathyroid gland was achieved with subsequent resolution of calcium and parathyroid levels. Each adenoma was located within the vagus nerve below the level of the carotid bifurcation and was enucleated without sacrificing the vagus nerve. In our cases and those reported previously, the parathyroid glands were supernumerary, representing parathyroid tissue embryologically derived from the third branchial pouch. Exploration for hyperparathyroidism requires a complete, meticulous surgical dissection to identify all parathyroid glands and to search for possible accessory tissue in selected cases. Our experience and a review of the literature serve to emphasize that, although rare, intravagal parathyroid adenomas do occur. Examination of the vagus nerve should therefore be strongly considered when four normal glands are found, as intravagal adenomas appear to represent accessory ectopically located parathyroid tissue.