Endoscopic Endonasal Resection of a Pure Optic Canal Cavernous Malformation Presenting as Progressive Optic Neuropathy.

BACKGROUND AND OBJECTIVE: Cavernous malformations (CMs) are relatively common in the brain parenchyma, whereas lesions strictly confined to the optic canal are exceptionally rare. Although only a few intracanalicular vascular malformations have been reported, detailed descriptions of pure optic canal CMs remain scarce. We report a pure optic canal CM successfully managed by endoscopic endonasal surgery to further highlight the surgical feasibility and clinical efficacy of this strategy. CASE DESCRIPTION: A 48-year-old woman presented with a 3-month history of progressive right visual decline that accelerated shortly before admission. Ophthalmological examinations showed decreased best-corrected visual acuity, a relative afferent pupillary defect, concentric visual field narrowing, and thinning of the ganglion cell layer on optical coherence tomography. Magnetic resonance imaging (MRI) demonstrated a well-circumscribed, homogeneously gadolinium-enhancing mass entirely within the right optic canal, whereas computed tomography showed no calcification or canal enlargement. Vision improved transiently after systemic corticosteroids but relapsed with tapering, suggesting a compressive lesion. Given the rapid progression of vision loss, endoscopic endonasal surgery was conducted. RESULTS: Through a right nasal approach, the optic canal was unroofed and a dark-reddish, well-circumscribed lesion with minimal adhesion was removed en bloc. There was negligible blood loss and no intraoperative or postoperative cerebrospinal fluid leakage. A CM was confirmed by histopathology. Postoperatively, visual acuity and field recovered fully, and MRI confirmed gross total resection with complete decompression of the optic nerve. CONCLUSION: This case adds an additional well-documented example of a pure optic canal CM and supports the endoscopic endonasal approach as a safe and useful option for achieving complete resection with excellent visual recovery.