Ancient schwannoma of the vagus nerve, resection with continuous monitoring of the inferior laryngeal nerve.

Schwannomas (neurinomas, neurilemmomas) are benign, single, slow-growing encapsulated tumors that originate in the sheath of cranial or spinal nerves, and that rarely undergo malignant transformation. Descriptions have shown that about 25% of cases occur in the head and neck; there are only 95 references of vagus nerve involvement. These tumors appear mostly between the third and fifth decades of life; there is no sex predominance. The clinical picture usually consists of a relatively pain-free bulge in the neck; the differential diagnosis should be made with other parapharyngeal tumors or neoplasms in the jugular foramen. The senile schwannoma (SS) is a rare variant that was first described by Ackrman and Taylor in 1951; its features are: wide areas of hyalinized matrix, hypercellularity with nuclear polymorphism and cell hyperchromatism. A microscopic description of SS in serial and histological sections reveals two cell types: the Antoni type A or fasciculated type (elongated cells, arranged in intertwining bundles in various directions or in a spiral layout), and the Antoni type B or reticular type (polymorphic cells that define small vacuoles, giving the tumor a honeycomb aspect). Antoni type B cells predominate in SS. Absence of mitosis is the main feature that differentiates a SS from a malignant schwannoma. Twelve cases of head and neck SSs have been described so far, of which one involved the vagus nerve. Surgery is the treatment of choice; there is a high rate of vagus nerve injury during this procedure. There are descriptions of resections of vagus nerve schwannomas associated with neurostimulation and observation of esophageal6 contractions or endoscopic visualization of the larynx. The current article is the first case report of resection of a vagus nerve schwannoma under continuous electrophysiological monitoring of the recurrent laryngeal nerve.