Clinical Study of Non-invasive 40-Hz Audiovisual Stimulation Guided by Gamma EEG Monitoring for Promoting Perioperative Brain Function Recovery in Children

Inclusion Criteria: * Children aged 3-6 years, irrespective of sex, representing the critical period of brain network development. Classified as American Society of Anesthesiologists (ASA) Physical Status I or II. Scheduled to undergo elective single-session surgery under general anesthesia (including inhalational anesthesia with agents such as sevoflurane) with an expected anesthesia duration of ≥1 hour, including procedures such as inguinal hernia repair, orchiopexy, and adenoidectomy. Normal preoperative neurodevelopment as assessed by routine clinical evaluation, with parents or legal guardians able to understand the study protocol and willing to provide written informed consent. Exclusion Criteria: * A preoperative diagnosis of autism spectrum disorder (ASD), epilepsy, intellectual developmental disorder, attention-deficit/hyperactivity disorder (ADHD), or any other neurological or psychiatric disorder. Severe visual impairment (e.g., cataract or amblyopia) or significant hearing impairment that would preclude the administration of synchronized audiovisual stimulation. A personal or family history of photosensitive epilepsy, owing to safety considerations. Occurrence of major anesthesia-related complications during surgery, including severe allergic reactions, malignant hyperthermia, prolonged severe hypoxemia, or other serious perioperative adverse events.