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

backgroundOptic 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.