Ventral brain stem schwannoma at the entry zone of the hypoglossal nerve.

The unusual case of a ventral brain stem schwannoma located at the entry zone of the hypoglossal nerve in a 49-year-old woman is reported. The diagnosis of a schwannoma was confirmed histologically after partial tumor resection via the dorsolateral, suboccipital, transcondylar approach. Hypotheses for the pathogenesis of intramedullary schwannomas are discussed.