Developmental patterns of and surgical strategy for trigeminal neurinomas

Developmental patterns of 26 trigeminal neurinomas (TNs) were analyzed for safe and complete removal. TNs were located in one or more of the three distinct compartments, i.e. the posterior fossa (P), the middle fossa (M), and the extracranial space (E). Our cases were classified into six categories according to the location, type P (5 cases), type M (4), type E (1), and dumbbell tumors; type PM (9), type ME (4), and type PME (2). From the point of surgical strategy, the extracranial extension patterns should be divided into two groups: the orbital extension and the infratemporal fossa extension. Based on our recent experiences, all TNs can be completely and safely removed by a single approach, the subtemporal epidural (interdural) approach with two options: 1) anterior petrosectomy for the posterior fossa compartment, 2) zygomatic or orbitozygomatic craniotomy for the extracranial compartments (infratemporal) fossa or orbit).