Endoscopic Resection of a Large V3 Intracranial and Infratemporal Fossa Schwannoma

Objectives This study will inform readers of a large type D trigeminal schwannoma resected through a unique endoscopic endonasal and endoscopic sublabial transmaxillary approach.

Background Type D trigeminal schwannomas are rare and often require multiple approaches to access the intracranial and extracranial components. External approaches such as the middle fossa extradural approach or transmandibular approach are more invasive with increased morbidity. The endoscopic endonasal approach for trigeminal schwannomas has recently gained in popularity and has shown to be a feasible approach for the majority of these tumors.

Study Design Case presentation.

Methods A 30-year-old woman presented with cough and unilateral serous otitis media. Upon work-up, she was found to have a dumbbell shaped 3.5 × 4.2 × 4.7 cm mass originating from the foramen ovale, involving the left middle cranial fossa and infratemporal fossa. The large middle fossa component (4 cm in transverse diameter) was causing mass effect on the cavernous sinus. The patient underwent a minimally invasive approach using an extended endoscopic endonasal and endoscopic sublabial transmaxillary approach with access to the middle cranial fossa, pterygopalatine fossa, and infratemporal fossa. The endoscopic sublabial transmaxillary approach involved a small gingivobuccal sulcus incision, followed by entry into the maxillary sinus through the canine fossa with room enough for an endoscope and instrumentation. The posterior wall of the maxillary sinus was opened and the internal maxillary artery was ligated. After dissection of the pterygoid musculature, all margins of the tumor were able to be accessed and the extra-axial component in the middle cranial fossa was resected without dural violation. Maxillary division of the trigeminal nerve was preserved. Intraoperative pathology confirmed the diagnosis of benign peripheral nerve sheath tumor. The tumor was resected in entirety with reconstruction of the middle cranial fossa with contralateral nasoseptal flap and autologous fat graft. Postoperatively, the patient has done well with no occurrence of bleeding, cerebrospinal fluid leak, or cranial nerve deficits other than expected anesthesia in the V3 distribution.

Conclusion We present a large V3 schwannoma with intracranial and extracranial components resected entirely via extended endoscopic endonasal and endoscopic sublabial transmaxillary approach. Prior articles have suggested a relative contraindication for endoscopic endonasal approach includes middle cranial fossa component more than 2.5 cm. In this case, we safely removed a large V3 schwannoma with 4 cm middle cranial fossa component in addition to infratemporal fossa component through a unique approach. The addition of the endoscopic sublabial transmaxillary approach to the standard endoscopic endonasal approach enabled improved access with a more direct angle to the tumor. This is the first reported case of such a large V3 schwannoma resected through an extended endoscopic endonasal and endoscopic sublabial transmaxillary approach.