[Endoscopic Surgery for Trigeminal Schwannoma]

Minimally invasive surgical techniques, including the endoscopic endonasal transmaxillary-pterygoid approach (EETMPA), the endoscopic transorbital approach (ETOA), and the endoscopic keyhole approach (EKA), have recently been applied to the surgical treatment of trigeminal schwannomas. However, criteria for patient selection and technical nuances remain sparsely reported; therefore, we describe these aspects based on our previous work. For patient selection, a sufficient surgical corridor to the tumor from the paranasal sinus must be identified on magnetic resonance imaging to perform EETMPA. To create an adequate working space, wide sphenoidotomy and ethmoidectomy are required, along with removal of the medial and posterior walls of the maxillary sinus and opening of the pterygopalatine fossa. These steps allow access to Meckel's cave through the quadrangular space, formed by the cavernous and petrous internal carotid arteries, the abducens nerve, and V2. During tumor resection, intracapsular dissection is essential to preserve normal trigeminal nerve fibers. Precise patient selection and intracapsular resection may have contributed to the favorable surgical outcomes of EETMPA for non-vestibular schwannoma. With the accumulation of further clinical experience, criteria for selecting EETMPA, ETOA, or EKA are expected to become clearer.