Giant Serpentine Distal Anterior Cerebral Artery Aneurysm Treated with In Situ Side-to-Side A3-A3 Anastomosis and Aneurysm Resection

Giant serpentine aneurysms that occur in the distal anterior cerebral artery are extremely rare and challenging to manage because of their complex structure. In this case, we show an aneurysm resection performed after in situ side-to-side A3-A3 bypass to treat a giant serpentine distal anterior cerebral artery aneurysm.Here, we present the case of a 55-year-old man with a giant distal anterior cerebral artery serpentine aneurysm who presented with severe headache and progressive unconsciousness. Computed tomography and cerebral angiography revealed a giant serpentine aneurysm in the right A2 segment. Both the right pericallosal and callosal marginal arteries branched from the outflow tract. To relieve the mass effect and preserve distal blood flow, an in situ side-to-side A3-A3 anastomosis and a partial aneurysm resection were performed sequentially. Postoperative cerebral angiography revealed no aneurysm blood filling and good perfusion in both anterior cerebral artery territories.Anterior cerebral artery giant serpentine aneurysms are rare and usually present with headache and mass effect. Aneurysm resection and distal flow protection are issues that we must consider. The sequential procedure of anastomosis and aneurysm resection is a feasible and safe option.