Endoscopic Endonasal Approach for Primary Optic Nerve Sheath Meningioma: A Systematic Review

Primary optic nerve sheath meningioma (ONSM) is a rare but clinically significant benign tumor that can cause irreversible loss of vision. Active management strategies in primary ONSM are controversial, and current treatment favors radiotherapy, despite its associated risks. Endoscopic endonasal approach (EEA) surgery offers a minimally invasive alternative to decompress the optic nerve and restore visual function. This systematic review evaluates the effectiveness and safety of EEA for decompression of the optic nerve, focusing on visual outcomes and complications.

A systematic review was performed following PRISMA guidelines to identify studies reporting operative management using EEA in patients above 16 years with radiographically confirmed primary ONSM that demonstrate optic canal confinement, excluding studies evaluating secondary ONSM or tumors with any evidence of intracranial extension. Post-operative outcome data were collected including visual acuity (VA), visual fields and complications.

A total of 1065 articles were screened, with 13 patients included across 5 studies. VA improved post-operatively in 5 out of 13 patients (≥ 0.2 decrease in VA LogMAR score) and VA scores were stable in 7 out of 13 patients, post-operatively (where change in LogMAR score <0.2). One patient had worsened vision at 2-year follow-up (>0.2 increase in VA LogMAR score). Of note, this patient had established criteria for "poor vision" pre-operatively, as defined by World Health Organization (WHO) (≥ 0.5 LogMAR) and although vision was stable during the first 6 months of follow-up, VA deteriorated to WHO criteria for blindness (LogMAR > 1.3) with scores of 1.38 and 1.78 LogMAR at 12 and 24 months, respectively. No intraoperative or postoperative complications were reported in the included studies.

These results suggest that EEA offers a safe and effective minimally invasive approach in preserving threatened vision for selected primary ONSM cases. Further research is required to determine optimal timing, long-term efficacy, and integration with radiotherapy.