The goal of this interventional study is to learn about the efficacy and safety of Esketamine for treating children with Rett syndrome (RTT).
The main questions it aims to answer are:
* whether Esketamine treatment is effective in improving symptom severity for RTT.
* whether Esketamine is safe in the treatment of RTT. Participants will receive a weekly intravenous infusion of Esketamine for five weeks and will be assessed for disease severity and drug safety.