Neuroendoscopic Resection of Trigeminal Schwannoma in the Pterygopalatine/Infratemporal Fossa via the Transnasal Perpendicular Plate Palatine Bone or Transnasal Maxillary Sinus Approach

Background: Both the pterygopalatine fossa (PPF) and the infratemporal fossa (ITF) lie outside the midline of the skull base. Lesions in the PPF or ITF include trigeminal schwannoma (Trigeminal Schwannoma, TS), which originates from the second or third branch of the trigeminal nerve (maxillary nerve or mandibular nerve). Due to their typically deep anatomical location, lesions in the PPF or ITF can be difficult to treat using traditional surgical approaches. In recent years, because of their advantage of close-up observation, neuroendoscopic techniques are increasingly being applied in skull base surgery, especially in treating lesions around the midline of the skull base.

Objective: This study aims to (1) explore the neuroendoscopic treatment of lesions in PPF or ITF via the transnasal palate bone perpendicular plate or transnasal maxillary sinus approach and (2) analyze the clinical significance of this approach.

Methods: We retrospectively analyzed three cases of PPF TSs and one case of ITF TS treated between January 2015 and May 2017. All of the cases underwent neuroendoscopic resection of TSs located in the PPF via the nasal perpendicular plate palatine bone (or nasal maxillary sinus) approach.

Results: Two cases of PPF TSs were characterized by a thin palate bone perpendicular plate due to oppressed absorption of the tumor. Therefore, the endoscopic transnasal palate bone perpendicular plate approach was employed. Additionally, one case of PPF TSs and one case of ITF TS were resected via the transnasal maxillary sinus approach. All four patients received total resection under endoscopy and recovered well following their respective operations without cerebrospinal fluid leakage, although one patient experienced postoperative dry eye symptoms and another patient showed no improvement in facial numbness between pre- and postoperation.

Conclusion: Neuroendoscopic surgery performed via the transnasal perpendicular plate palatine bone or transnasal maxillary sinus approach has its own unique advantages in removing TSs in PPF and in ITF: notably, the tumor can be exposed and attacked under direct vision, which can protect important structures, such as the internal carotid and maxillary nerves, while at the same time helping to achieve total removal of TSs. Furthermore, by adopting this approach versus traditional skull base surgery, postoperative trauma can be reduced significantly, which should be advocated for in this time of minimal invasive surgery.

No conflict of interest has been declared by the author(s).