Asymptomatic Purely Intracranial Vagal Schwannoma: Clinical Case Report and Literature Review.

Vagus nerve schwannoma is an infrequently occurring schwannoma, in which a distinct subtype exists wherein the tumor is confined to the cerebellomedullary cistern without invading the jugular foramen. This unique tumor is called purely intracranial vagal schwannoma. In this case report, we present a case of purely intracranial vagal schwannoma in its asymptomatic early phase, incidentally discovered during surgery performed on a patient with hemifacial spasm. Because of the small size of the tumor, we definitively recognized that it originated from the second rootlet on the caudal side. The tumor was totally resected uneventfully and a favorable prognosis was achieved. Furthermore, we conducted a comprehensive literature review to summarize the classification, origin, and surgical complications associated with this rare tumor type. Based on our literature review, we propose that: 1) the origin of tumor is related to the time of onset of symptoms, 2) nearly all purely intracranial vagal schwannomas can be entirely resected and favorable prognosis can be achieved, and 3) surgeons should be aware of potential cardiovascular complications during surgical procedures.