This prospective randomized controlled trial evaluates whether individualized cardiac index-guided intraoperative hemodynamic management reduces postoperative transient ischemic episodes in pediatric patients undergoing encephaloduroarteriosynangiosis (EDAS) for Moyamoya disease. Patients are randomized 1:1 to goal-directed fluid therapy based on baseline cardiac index versus standard arterial pressure-based management. The primary outcome is the incidence of transient ischemic episodes during hospitalization.