Surgical strategy for tumors located in or extending from the intracranial space to the infratemporal fossa - Advantages of the transcranial approach (zygomatic infratemporal fossa approach) and the indications for a combined transcranial and transcervical approach

The surgical strategy for tumors located in or extending from the intracranial space to the infratemporal fossa was analyzed in 12 cases with various pathologies. A case of mandibular nerve schwannoma, which extended 1 cm below the external orifice of the foramen ovale, was completely removed via the epidural subtemporal approach without zygomatic osteotomy with partial removal of the middle cranial base. The inferior margin of infratemporal tumor could be accessed via the transcranial route with zygomatic or orbitozygomatic osteotomy without complications including facial nerve injury in nine cases, and the lowest level of the infratemporal tumors was approximately 4.5 cm below the outer surface of the middle cranial base. In five of these 9 cases (2 schwannomas, 1 myxoma, 1 chondrosarcoma, and 1 malignant peripheral nerve sheath tumor), the tumors were localized in the infratemporal fossa, and in the other 4 cases (2 meningiomas, 1 glioblastoma, and 1 ameloblastoma), the tumors extended to both the intracranial space and the infratemporal fossa. In two cases (recurrent jugular schwannoma and mandibular osteosarcoma), a combined transcranial and transcervical approach (mandibular swing approach) was essential, because the resection line of the lower margin was too far from the middle cranial base. These results indicate that the transcranial approach, with or without zygomatic or orbitozygomatic osteotomy (zygomatic infratemporal fossa approach), is safe and effective for removal of some infratemporal tumors, and that a combined transcranial and transcervical approach is useful for removing infratemporal tumors with extensive downward extension.