2026 Proffered Presentations
S294: INDICATIONS AND LIMITATIONS OF ENDOSCOPIC TRANSNASAL SURGERY FOR POSTERIOR FOSSA INTRADURAL TUMORS: INSIGHTS FROM 53 CASES
Hirotaka Hasegawa, MD, PhD1; Masahiro Shin, MD, PhD2; Shunya Hanakita, MD, PhD1; Hideaki Ono, MD, PhD3; Yuki Shinya, MD, PhD3; Motoyuki Umekawa, MD3; Satoshi Koizumi, MD3; Naoyuki Shono, MD, PhD3; Taichi Kin, MD, PhD3; Nobuhito Saito, MD, PhD3; 1Saitama Medical Center, Saitama Medical University; 2Teikyo University; 3The University of Tokyo
Introduction: Open craniotomy is the benchmark for intradural posterior fossa tumors, yet endoscopic transnasal surgery (ETS) promises comparable oncologic control with less morbidity. Its exact indications and safety remain debated.
Objective: To clarify the role of ETS for these tumors through a single-center series.
Methods: We retrospectively reviewed 53 consecutive patients (June 2016 – April 2025). Twenty-nine had pure intradural lesions (IT) and 24 skull-base tumors with intradural extension (SB-IE). All procedures used a transclival route; pituitary transposition or transodontoid extension was added when required. Resection grade and morbidity were assessed from operative notes and postoperative MRI.
Results: Histology and brain-stem distribution are shown in Figure 1.
Gross, near-total, subtotal (>90 %), and partial (<90 %) resections numbered 16, 12, 18, and 7 cases, respectively. Limiting factors were lateral spread to cranial nerves, caudal extension beyond the odontoid, dense neurovascular adhesion, and tumor firmness. All cases experienced intra-operative high-flow cerebrospinal fluid leakage; six early patients required re-operation. After routine suture-based closure began in May 2023, leakage dropped to 0/20 versus 6/33 previously. Transient abducens palsy occurred in eight patients (15 %); mild but permanent ocular palsy in one (2 %); other morbidity was minor. Resection rates and complications did not differ between IT and SB-IE cohorts. Illustrative cases are shown in Figure 2 (foramen magnum meningioma), 3 (cerebellopontine angle epidermoid cyst), and 4 (posterior clinoid meningioma).
Conclusions: ETS affords effective resection with functional preservation when lesions lie medial to cranial nerves and rostral to the odontoid. Lateral reach is reliable inside the cranial-nerve plane, whereas ultimate resectability depends on tumor consistency and adhesiveness. Even in cases beyond these boundaries, ETS may play a valuable role within a multimodal treatment strategy aimed at decompression and functional preservation. ETS therefore represents a valuable standalone or adjunct option within multimodal strategies for posterior fossa disease.