Apollo microcatheter-assisted transvenous embolization for brain arteriovenous malformation with a tortuous stenotic drainage vein and "Caput Medusa" sign: a case report.

Introduction and importance: Transvenous embolization (TVE) for brain arteriovenous malformations (AVMs) typically requires two microcatheters or a dual-lumen mini-balloon catheter in the draining vein. A single Apollo microcatheter can replace these devices, offering a novel TVE alternative for AVMs with the "Caput Medusa" sign. This case report describes the technique, as such reports remain limited. Case presentation: A 34-year-old male patient suffered intracranial hemorrhage and developed right-sided hemiplegia and aphasia. Angiography revealed a left corpus callosum AVM supplied by the left anterior cerebral artery and lenticulostriate artery, with drainage into a thick vein exhibiting the "Caput Medusa" sign. After navigating the tortuous, stenotic distal draining vein using an Apollo microcatheter, TVE was performed through the following sequential steps: coiling of the left distal anterior cerebral artery, temporary occlusion of the left internal carotid artery, maintenance of blood pressure below 100 mm Hg, and injection of Onyx-18 via the Apollo microcatheter to achieve complete AVM obliteration. Postoperatively, no new neurological deficits were observed. On postoperative day 40 follow-up, he could walk with right muscle strength grade 4 and had normal speech function. Clinical discussion: The "Caput Medusa" sign of the AVM is produced by the convergence of multiple shunts into a thick proximal draining vein, making the draining vein system clearly visible. The Apollo microcatheter is soft and can navigate through the tortuous and stenotic drainage vein. Conclusion: The "Caput Medusa" sign of the AVM facilitates TVE visualization. TVE may be feasible in selected AVMs when a single Apollo microcatheter is used.