Endoscopic Transnasal Surgery for Purely Intradural Lesions in the Posterior Fossa

Background: The posterior fossa (PF) houses many vital neurovascular structures, making it a region with high surgical complexity. Although endoscopic transnasal surgery (ETS) has become increasingly applied to clival tumors with or without intradural extension, there are no comprehensive reports on the application of ETS to “purely” intradural tumors in the PF. We have proactively applied ETS for PF tumors located medially to the cranial nerves after confirming accessibility using three-dimensional computer graphics-based simulation.

Methods: Since April 2018, ETS was performed for 15 cases of purely intradural tumors located in or extending to the PF (6 meningiomas, 5 purely intradural chordomas, 3 epidermoid cysts, and 1 craniopharyngioma). The surgical outcomes, including extent of resection (total/near-total vs. subtotal vs. partial) and complications were summarized. For tumors located in the PF (8 cases), trans-clival approach was mainly used with or without modifications. For tumors located in the parasellar region and extending to the PF (7 cases), pituitary transposition was utilized to connect both parasellar and transclival surgical fields.

Results: The tumor locations were described as upper retroclival in 5, middle retroclival in 4, cerebellopontine angle in 2, petroclival in 1, and jugular tubercle in 1. The illustrative cases are shown in [Figs. 1] to [3]. There were 2 large tumors spanning multiple skull base regions. Total/near-total resection was achieved in 9 (60%), subtotal resection in 4 (27%), and partial resection in 2 (13%). Lumbar drainage was used in 10 earlier cases; water-tight dural suturing was used in the recent 5 cases without lumbar drainage. Transient abducens nerve palsy was observed in 4 (27%) cases and resolved within a few months. Chronic subdural hematoma was observed in 1 (7%) case, which resolved with conservative treatment. One patient was brought back to the operative theater on postoperative day 1 due to self-extraction of the sinus balloon. Cerebrospinal fluid leakage occurred in 1 (7%) case in which pituitary transposition was performed. For the subtotally or partially resected tumors, five underwent radiosurgery and one underwent redo surgery upon recurrence.

Conclusion: ETS allows for a minimally invasive approach to the PF. The complication rate was acceptable given deep skull base location of the tumors.

Fig. 1 ETS for jugular tubercle meningioma (total resection).

Fig. 2 ETS for cerebellopontine angle epidermoid cyst (total resection).

Fig. 3 ETS (partial resection) and planned upfront radiosurgery for large clival meningioma.

Fig. 4 ETS for posterior clival meningioma (near-total resection).

Publication History

Article published online:
07 February 2025