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

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. 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. 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. 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.