Microsurgical resection of an intrinsic optic nerve cavernous malformation through a transsylvian approach: illustrative case.

BACKGROUND: Optic pathway cavernous malformations (CMs) are rare lesions that may cause progressive or fluctuating visual deterioration through recurrent hemorrhage and chronic compression. Optimal management and surgical timing remain controversial. OBSERVATIONS: A 30-year-old male presented with progressive right-sided visual decline after recurrent episodes of visual loss since 2018. Initial near-complete visual loss was followed by spontaneous recovery, supporting conservative follow-up. Sustained deterioration later prompted reevaluation. Neuro-ophthalmological examination demonstrated optic disc pallor, retinal nerve fiber layer defects on optical coherence tomography, and severe temporal and inferior visual field deficits. MRI revealed a hemorrhagic lesion intrinsic to the right optic nerve adjacent to the internal carotid artery bifurcation, consistent with a CM. The lesion was resected through a right pterional transsylvian approach with optic canal unroofing and falciform ligament release. Gross-total resection was achieved while preserving the pial vascular supply and surrounding perforators. Postoperative imaging confirmed complete excision, and visual function partially improved at 3 months. LESSONS: Timely microsurgical treatment may be considered for symptomatic optic nerve CMs with progressive or recurrent visual deterioration before irreversible injury develops. A transsylvian approach with optic canal decompression can provide favorable exposure while limiting manipulation of the optic apparatus and adjacent neurovascular structures. https://thejns.org/doi/10.3171/CASE26503.