Segment a2 of the right anterior cerebral artery with a nodular protrusion suggests the possibility of aneurysm, vascular malformation, and vasospasm. Nodular bulge in the right anterior cerebral artery a2 segment, a finding obtained by cranial magnetic resonance imaging + cerebral angiography, suggests the possibility of aneurysm, vascular malformation, or vasospasm. In order to clarify whether it is an aneurysm, vascular malformation or vasospasm, in addition to the combination of clinical manifestations, it is necessary to improve the DSA examination. After confirming aneurysm, surgical treatment should be considered; if it is vascular malformation, it is generally congenital and can be observed without special circumstances; if it is vasospasm, vasodilatation can be given when there are symptoms. It is recommended that patients with a2 segment of the right anterior cerebral artery with a nodular protrusion should consult a specialized doctor in the hospital in a timely manner.