Successful shrinkage of anterior communicating artery aneurysm after ACA–ACA bypass with interposed occipital artery graft in pediatric moyamoya disease: illustrative case

BACKGROUND: Selecting therapeutic options for moyamoya disease (MMD)-associated anterior communicating artery (ACoA) aneurysm, a rare pathology in children, is challenging because its natural course remains unclear. OBSERVATIONS: A 4-year-old boy exhibiting transient ischemic attacks was diagnosed with unilateral MMD accompanied by an unruptured ACoA aneurysm. Although superficial temporal artery to middle cerebral artery anastomosis eliminated his symptoms, the aneurysm continued to grow after surgery. Since a previous craniotomy and narrow endovascular access at the ACoA precluded both aneurysmal clipping and coil embolization, the patient underwent a surgical anastomosis incorporating an occipital artery graft between the bilateral cortical anterior cerebral arteries (ACAs). This was intended to augment blood flow in the ipsilateral ACA territory and to reduce the hemodynamic burden on the ACoA complex. The postoperative course was uneventful, and radiological images obtained 12 months after surgery revealed good patency of the bypass and marked shrinkage of the aneurysm in spite of the intact contralateral internal carotid artery. LESSONS: Various clinical scenarios should be assessed carefully with regard to this pathology. Bypass surgery aimed at reducing flow to the aneurysm might be an alternative therapeutic option when neither coiling nor clipping is feasible.