The Effects of Preoperative Intranasal Administration of Dexmedetomidine and Esketamine on Negative Postoperative Behavioral Changes in Children With Autism Spectrum Disorder

The goal of this clinical trial is to learn whether intranasal sedation given before anesthesia can lower negative postoperative behavioral changes in children with autism spectrum disorder who undergo elective surgery. The study will compare two commonly used sedative medicines with a saline control. It will also examine the safety of these medicines and explore how brain electrical activity during recovery may relate to later behavior changes. The main questions this study aims to answer are: * Does intranasal dexmedetomidine given before anesthesia lower negative postoperative behavioral changes seven days after surgery in children with autism spectrum disorder? * Does intranasal esketamine given before anesthesia lower negative postoperative behavioral changes seven days after surgery in children with autism spectrum disorder? * Are there differences in postoperative agitation, pain, and sedation quality among the three groups? Researchers will compare dexmedetomidine, esketamine, and saline to see whether either medicine works better than saline in reducing postoperative behavior changes. Participants will: * Be randomly assigned to receive intranasal dexmedetomidine, intranasal esketamine, or intranasal saline about thirty minutes before anesthesia * Undergo their planned surgery with standard general anesthesia care ③ Be assessed for behavior changes at three, seven, and twenty-eight days after surgery ④ Have routine monitoring of recovery, pain, agitation, and safety outcomes during and after surgery