Use of Endoscopic Technique in Resection of Trigeminal Schwannoma

Objectives: To investigate the outcomes of endoscopic endonasal surgery for trigeminal schwannomas and the anatomical determinants of a combined surgical approach.

Methods: Seven patients who underwent resection of trigeminal schwannoma involving an endoscopic endonasal approach at the authors’ institution between January 2006 and May 2019 were reviewed.

Results: Four lesions (57%) involved V2, 1 (14%) lesion involved V3, and 2 lesions extended into the sphenoid sinus (29%). Three tumors (43%) extended intracranially (Table 1). Two patients underwent combined intracranial approaches with frontotemporal (n = 1) and subtemporal craniotomy (n = 1). Both of these tumors had considerable intracranial extension into Meckel's cave ([Fig. 1]). Three patients underwent a combined endoscopic and Caldwell–Luc approach. Two of the three tumors extended into the infratemporal fossa ([Fig. 2]), while one demonstrated extensive involvement of the orbital floor ([Fig. 3]). Two cases (29%) required endoscopic endonasal medial maxillectomy alone. The two purely endoscopic resections occurred in patients who were completely asymptomatic and without physical exam deficits, while the remainder of the patients reported preoperative facial numbness, pain, or both. Moreover, these two lesions were the smallest tumors of the cohort as measured by greatest overall image-based dimension (mean = 2.7 vs. 5.1 cm for the other five lesions). Gross total resection was felt to be achieved in six of seven cases, with no postoperative cerebrospinal fluid leaks. At initial postoperative follow-up (mean = 1.1 months following surgery), all patients with preoperative facial numbness had persistent numbness. Of the three patients without preoperative numbness, two demonstrated new sensory deficits. The mean total duration of follow-up was 14.1 months. By most recent follow-up, resolution of facial numbness was reported in one patient who had exhibited new early postoperative numbness.

Conclusions: An endoscopic approach is safe for resection of smaller V2/V3 lesions with minimal to no intracranial extension. The addition of a Caldwell–Luc approach can assist in dissection, particularly with tumor extension into the infratemporal fossa or orbital floor.

Table 1 Tumor characteristics and surgical approach

Fig. 1 Trigeminal schwannoma with intra- and extracranial components.

Fig. 2 V2 schwannoma extending into the infratemporal fossa.

Fig. 3 V2 schwannoma with intraorbital extension.