Purely Endonasal Endoscopic Approaches for Extracranial Trigeminal Nerve Schwannoma

The aim of this study is to assess the effectiveness and safety of purely endonasal endoscopic resection of extracranial trigeminal schwannomas (TGSs), with assessment of surgical and clinical outcomes in order to identify optimal candidates for an endonasal endoscopic approach (EEA).

A retrospective review of patient's records operated for TGSs between 2008 and 2021 was conducted. Patients operated with a purely EEA were included in this study. Pictures from a frozen fresh cadaver head dissection were used to demonstrate the surgical approach and to show anatomic relationships, complexity of the surgical area and safe corridors for surgery.

A total of 5 patients (4 females and 1 male) were operated for TGS. All patients had facial numbness (100%) as a presenting symptom, followed by facial pain in 2 patients (40%), and orbital pain in 1 (20%). Also, 3 patients (60%) had a tumor originating at the level of the foramen ovale and 2 (40%) at the foramen rotundum. The mean tumor diameter was 3,7 ± 2 cm. Gross total resection were achieved in all cases. Postoperatively, 1 patient had severe mastication problems, 1 had blurred vision, and in the long-term follow-up, 1 had frontal sinusitis. The mean follow up was 106.6 (min:49, max:132, SD: 29.82) months. No recurrences were detected.

In cases with the extradural TGS having limited extension into Posterior Cranial Fossa, or located in the Middle Cranial Fossa, a purely EEA is possible even for tumors bigger in size. Unilateral endonasal corridors are adequate for resection in most cases.