Medial (Intra-cisternal) acoustic neuromas

The clinical characteristics of "medial" or "intra-cisternal" acoustic neur oma (AN) treated in our institute were reviewed. Among 466 patients with AN s in our series during the last 20 years, 6 patients (1.3%) were considered to fill the criteria of medial AN definition. Compared with those with non -medial ANs, the patients with medial ANs show a tendency to have cerebella r and/or cranial nerve dysfunction (especially trigeminal and/or facial ner ves) in addition to hearing loss at the time of initial presentation. On ma gnetic resonance imaging, medial AN is visualized as a multi-cystic mass le sion in the cerebello-pontine cistern without extension into the internal a uditory canal in most cases. Although total removal of tumor was achieved i n all cases, the results of preservation of facial nerve function were not satisfactory. Medial AN can be considered as a clinical, but not pathologic al, subtype in terms of the functional outcomes of the facial nerve and hea ring.