Technical nuances of endoscopic transcortical transventricular fenestration for management of giant suprasellar arachnoid cysts in adults: illustrative cases.

BACKGROUND: Arachnoid cysts (ACs) are collections of CSF within an arachnoid membrane. Suprasellar ACs (SACs) constitute 1%-9% of all ACs, with giant SACs representing a rarer subset at increased risk of rupture, intracranial hemorrhage, and neurological deficits. While ventriculostomy is well characterized, anatomical considerations and technical nuances of cystocisternostomy remain limited; adult presentation and outcomes remain poorly defined. The authors describe surgical technique and postoperative outcomes in 2 adult patients undergoing endoscopic ventriculocystocisternostomy for giant SACs. OBSERVATIONS: Both cases were managed with endoscopic transventricular ventriculocisternostomy. Intraoperatively, an absent tuber cinereum allowed for cyst wall fenestration under direct visualization. The first case was a 33-year-old male with bitemporal hemianopsia, headaches, and memory loss. He experienced significant improvement in his bitemporal hemianopsia and resolution of headaches at 1 year. The second case was a 36-year-old female with debilitating daily headaches, which decreased to one or two episodes per week at 5 months postoperatively. Follow-up imaging demonstrated decreased cyst size and mass effect. LESSONS: Giant ACs warrant closer surveillance and often surgery due to higher risks of deficits. Careful anatomical orientation and controlled dual fenestration are key to achieving durable decompression. Endoscopic ventriculocisternostomy is a feasible and effective approach for symptomatic SACs. https://thejns.org/doi/10.3171/CASE26372.