Purely Endoscopic Subtemporal Keyhole Approach for Trigeminal Schwannomas: Surgical Techniques and Early Results.

Background and objectives: In the past, microscopic transcranial approach was the mainstay of treatment of trigeminal schwannomas. In recent years, several endoscopic procedures have been reported for trigeminal schwannomas. For trigeminal schwannomas arising around the Meckel cave, we introduced a fully endoscopic procedure with a small temporal craniotomy in June 2020 and have performed radical tumor removal as in the conventional approach. This article describes the details of the purely endoscopic subtemporal keyhole approach (PESKA) surgical procedure and reports the initial surgical results.

Methods: Between June 2020 and November 2023, 8 cases of trigeminal schwannoma were treated with PESKA. The mean tumor diameter was 33.1 mm. The surgical procedure for PESKA consists of a 7-cm linear skin incision made upward from the anterior to the auricle on the side of the lesion, followed by a 4-cm temporal craniotomy and then endoscopic manipulation. The intradural part of the middle cranial fossa is observed, and the Meckel cave is identified and opened. The tumor is removed with preserving most normal trigeminal nerve fibers. The site of the lesion, the extent of resection, complications, operative time, Karnofsky Performance Status, and intraoperative blood loss were evaluated.

Results: All 8 patients underwent gross total resection. Only one patient had new temporal edema on the side of the lesion, which was asymptomatic. The mean operative time was 4 hours and 21 minutes.

Conclusion: We report on PESKA, a fully endoscopic procedure with a small temporal craniotomy for a trigeminal schwannoma arising around the Meckel cave. The use of an endoscope allowed for a wide field of view, even in a narrow operative field, reducing brain traction and allowing radical resection of the tumor while preserving normal trigeminal nerve fibers. This method may represent an effective surgical alternative for trigeminal schwannomas.