Trigeminal neurinomas extending into multiple fossae: Surgical methods and review of the literature

Kazunari Yoshida, Takeshi Kawase

Research output: Contribution to journalArticlepeer-review


Object: Since 1974, 27 patients with trigeminal neurinomas (TNs) have been treated at Keio University Hospital and ancillary institutes. In the present study the clinical features and developmental patterns of these 27 cases are analyzed, and the clinical features of 402 cases reported in the literature are reviewed. Based on the analysis of the developmental patterns of the TNs, the surgical strategy for a one-stage removal of TNs involving multiple fossae is described. Methods: Trigeminal neurinomas are classified into six types according to tumor location. Types M, P, and E are tumors involving a single compartment, that is, the middle fossa, posterior fossa, or extra cranial space, respectively. Types MP (middle and posterior fossae), ME (middle fossa and extra cranial space), or MPE (middle and posterior fossae and extra cranial space) are tumors involving multiple compartments. Advances in neuroimagimg technologies, such as magnetic resonance imaging, have revealed a high incidence of TNs extending into multiple fossae, namely 36.2% in cases reported since 1983 and 59% in the authors' series. All but one of the most recent 19 patients in this series underwent skull base surgery, whereas the remaining nine patients were surgically treated via the conventional subdural approach. The rate of total tumor removal and clinical outcome were significantly better in those patients treated by skull base surgery than those treated by conventional surgery. Conclusions: The TNs extending into multiple fossae can be totally removed using the following singlestage surgical techniques: Type MP by the anterior transpetrosal approach; Type ME by the zygomatic or orbitozygomatic infratemporal approach; and Type MPE by the zygomatic transpetrosal approach. In 12 of 13 cases involving multiple fossae in this series, total tumor removal was achieved using single-stage skull base surgery.

Original languageEnglish
Number of pages1
JournalSkull Base Surgery
Issue number4
Publication statusPublished - 1999 Dec 1
Externally publishedYes

ASJC Scopus subject areas

  • Clinical Neurology


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